diff --git a/media/bufferpool/aidl/default/Accessor.cpp b/media/bufferpool/aidl/default/Accessor.cpp
new file mode 100644
index 0000000..e05b12a
--- /dev/null
+++ b/media/bufferpool/aidl/default/Accessor.cpp
@@ -0,0 +1,230 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#define LOG_TAG "BufferPoolConnection"
+
+#include "Accessor.h"
+#include "AccessorImpl.h"
+#include "Connection.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+void ConnectionDeathRecipient::add(
+        int64_t connectionId,
+        const sp<Accessor> &accessor) {
+    std::lock_guard<std::mutex> lock(mLock);
+    if (mAccessors.find(connectionId) == mAccessors.end()) {
+        mAccessors.insert(std::make_pair(connectionId, accessor));
+    }
+}
+
+void ConnectionDeathRecipient::remove(int64_t connectionId) {
+    std::lock_guard<std::mutex> lock(mLock);
+    mAccessors.erase(connectionId);
+    auto it = mConnectionToCookie.find(connectionId);
+    if (it != mConnectionToCookie.end()) {
+        uint64_t cookie = it->second;
+        mConnectionToCookie.erase(it);
+        auto cit = mCookieToConnections.find(cookie);
+        if (cit != mCookieToConnections.end()) {
+            cit->second.erase(connectionId);
+            if (cit->second.size() == 0) {
+                mCookieToConnections.erase(cit);
+            }
+        }
+    }
+}
+
+void ConnectionDeathRecipient::addCookieToConnection(
+        uint64_t cookie,
+        int64_t connectionId) {
+    std::lock_guard<std::mutex> lock(mLock);
+    if (mAccessors.find(connectionId) == mAccessors.end()) {
+        return;
+    }
+    mConnectionToCookie.insert(std::make_pair(connectionId, cookie));
+    auto it = mCookieToConnections.find(cookie);
+    if (it != mCookieToConnections.end()) {
+        it->second.insert(connectionId);
+    } else {
+        mCookieToConnections.insert(std::make_pair(
+                cookie, std::set<int64_t>{connectionId}));
+    }
+}
+
+void ConnectionDeathRecipient::serviceDied(
+        uint64_t cookie,
+        const wp<::android::hidl::base::V1_0::IBase>& /* who */
+        ) {
+    std::map<int64_t, const wp<Accessor>> connectionsToClose;
+    {
+        std::lock_guard<std::mutex> lock(mLock);
+
+        auto it = mCookieToConnections.find(cookie);
+        if (it != mCookieToConnections.end()) {
+            for (auto conIt = it->second.begin(); conIt != it->second.end(); ++conIt) {
+                auto accessorIt = mAccessors.find(*conIt);
+                if (accessorIt != mAccessors.end()) {
+                    connectionsToClose.insert(std::make_pair(*conIt, accessorIt->second));
+                    mAccessors.erase(accessorIt);
+                }
+                mConnectionToCookie.erase(*conIt);
+            }
+            mCookieToConnections.erase(it);
+        }
+    }
+
+    if (connectionsToClose.size() > 0) {
+        sp<Accessor> accessor;
+        for (auto it = connectionsToClose.begin(); it != connectionsToClose.end(); ++it) {
+            accessor = it->second.promote();
+
+            if (accessor) {
+                accessor->close(it->first);
+                ALOGD("connection %lld closed on death", (long long)it->first);
+            }
+        }
+    }
+}
+
+namespace {
+static sp<ConnectionDeathRecipient> sConnectionDeathRecipient =
+        new ConnectionDeathRecipient();
+}
+
+sp<ConnectionDeathRecipient> Accessor::getConnectionDeathRecipient() {
+    return sConnectionDeathRecipient;
+}
+
+void Accessor::createInvalidator() {
+    Accessor::Impl::createInvalidator();
+}
+
+void Accessor::createEvictor() {
+    Accessor::Impl::createEvictor();
+}
+
+// Methods from ::android::hardware::media::bufferpool::V2_0::IAccessor follow.
+Return<void> Accessor::connect(
+        const sp<::android::hardware::media::bufferpool::V2_0::IObserver>& observer,
+        connect_cb _hidl_cb) {
+    sp<Connection> connection;
+    ConnectionId connectionId;
+    uint32_t msgId;
+    const StatusDescriptor* fmqDesc;
+    const InvalidationDescriptor* invDesc;
+
+    ResultStatus status = connect(
+            observer, false, &connection, &connectionId, &msgId, &fmqDesc, &invDesc);
+    if (status == ResultStatus::OK) {
+        _hidl_cb(status, connection, connectionId, msgId, *fmqDesc, *invDesc);
+    } else {
+        _hidl_cb(status, nullptr, -1LL, 0,
+                 android::hardware::MQDescriptorSync<BufferStatusMessage>(
+                         std::vector<android::hardware::GrantorDescriptor>(),
+                         nullptr /* nhandle */, 0 /* size */),
+                 android::hardware::MQDescriptorUnsync<BufferInvalidationMessage>(
+                         std::vector<android::hardware::GrantorDescriptor>(),
+                         nullptr /* nhandle */, 0 /* size */));
+    }
+    return Void();
+}
+
+Accessor::Accessor(const std::shared_ptr<BufferPoolAllocator> &allocator)
+    : mImpl(new Impl(allocator)) {}
+
+Accessor::~Accessor() {
+}
+
+bool Accessor::isValid() {
+    return (bool)mImpl && mImpl->isValid();
+}
+
+ResultStatus Accessor::flush() {
+    if (mImpl) {
+        mImpl->flush();
+        return ResultStatus::OK;
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus Accessor::allocate(
+        ConnectionId connectionId,
+        const std::vector<uint8_t> &params,
+        BufferId *bufferId, const native_handle_t** handle) {
+    if (mImpl) {
+        return mImpl->allocate(connectionId, params, bufferId, handle);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus Accessor::fetch(
+        ConnectionId connectionId, TransactionId transactionId,
+        BufferId bufferId, const native_handle_t** handle) {
+    if (mImpl) {
+        return mImpl->fetch(connectionId, transactionId, bufferId, handle);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus Accessor::connect(
+        const sp<IObserver> &observer, bool local,
+        sp<Connection> *connection, ConnectionId *pConnectionId,
+        uint32_t *pMsgId,
+        const StatusDescriptor** statusDescPtr,
+        const InvalidationDescriptor** invDescPtr) {
+    if (mImpl) {
+        ResultStatus status = mImpl->connect(
+                this, observer, connection, pConnectionId, pMsgId,
+                statusDescPtr, invDescPtr);
+        if (!local && status == ResultStatus::OK) {
+            sp<Accessor> accessor(this);
+            sConnectionDeathRecipient->add(*pConnectionId, accessor);
+        }
+        return status;
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus Accessor::close(ConnectionId connectionId) {
+    if (mImpl) {
+        ResultStatus status = mImpl->close(connectionId);
+        sConnectionDeathRecipient->remove(connectionId);
+        return status;
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+void Accessor::cleanUp(bool clearCache) {
+    if (mImpl) {
+        mImpl->cleanUp(clearCache);
+    }
+}
+
+//IAccessor* HIDL_FETCH_IAccessor(const char* /* name */) {
+//    return new Accessor();
+//}
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
diff --git a/media/bufferpool/aidl/default/Accessor.h b/media/bufferpool/aidl/default/Accessor.h
new file mode 100644
index 0000000..8b43301
--- /dev/null
+++ b/media/bufferpool/aidl/default/Accessor.h
@@ -0,0 +1,204 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_ACCESSOR_H
+#define ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_ACCESSOR_H
+
+#include <android/hardware/media/bufferpool/2.0/IAccessor.h>
+#include <android/hardware/media/bufferpool/2.0/IObserver.h>
+#include <bufferpool/BufferPoolTypes.h>
+#include <hidl/MQDescriptor.h>
+#include <hidl/Status.h>
+#include "BufferStatus.h"
+
+#include <set>
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+using ::android::hardware::hidl_array;
+using ::android::hardware::hidl_memory;
+using ::android::hardware::hidl_string;
+using ::android::hardware::hidl_vec;
+using ::android::hardware::Return;
+using ::android::hardware::Void;
+using ::android::sp;
+
+struct Accessor;
+struct Connection;
+
+/**
+ * Receives death notifications from remote connections.
+ * On death notifications, the connections are closed and used resources
+ * are released.
+ */
+struct ConnectionDeathRecipient : public hardware::hidl_death_recipient {
+    /**
+     * Registers a newly connected connection from remote processes.
+     */
+    void add(int64_t connectionId, const sp<Accessor> &accessor);
+
+    /**
+     * Removes a connection.
+     */
+    void remove(int64_t connectionId);
+
+    void addCookieToConnection(uint64_t cookie, int64_t connectionId);
+
+    virtual void serviceDied(
+            uint64_t /* cookie */,
+            const wp<::android::hidl::base::V1_0::IBase>& /* who */
+            ) override;
+
+private:
+    std::mutex mLock;
+    std::map<uint64_t, std::set<int64_t>>  mCookieToConnections;
+    std::map<int64_t, uint64_t> mConnectionToCookie;
+    std::map<int64_t, const wp<Accessor>> mAccessors;
+};
+
+/**
+ * A buffer pool accessor which enables a buffer pool to communicate with buffer
+ * pool clients. 1:1 correspondense holds between a buffer pool and an accessor.
+ */
+struct Accessor : public IAccessor {
+    // Methods from ::android::hardware::media::bufferpool::V2_0::IAccessor follow.
+    Return<void> connect(const sp<::android::hardware::media::bufferpool::V2_0::IObserver>& observer, connect_cb _hidl_cb) override;
+
+    /**
+     * Creates a buffer pool accessor which uses the specified allocator.
+     *
+     * @param allocator buffer allocator.
+     */
+    explicit Accessor(const std::shared_ptr<BufferPoolAllocator> &allocator);
+
+    /** Destructs a buffer pool accessor. */
+    ~Accessor();
+
+    /** Returns whether the accessor is valid. */
+    bool isValid();
+
+    /** Invalidates all buffers which are owned by bufferpool */
+    ResultStatus flush();
+
+    /** Allocates a buffer from a buffer pool.
+     *
+     * @param connectionId  the connection id of the client.
+     * @param params        the allocation parameters.
+     * @param bufferId      the id of the allocated buffer.
+     * @param handle        the native handle of the allocated buffer.
+     *
+     * @return OK when a buffer is successfully allocated.
+     *         NO_MEMORY when there is no memory.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus allocate(
+            ConnectionId connectionId,
+            const std::vector<uint8_t>& params,
+            BufferId *bufferId,
+            const native_handle_t** handle);
+
+    /**
+     * Fetches a buffer for the specified transaction.
+     *
+     * @param connectionId  the id of receiving connection(client).
+     * @param transactionId the id of the transfer transaction.
+     * @param bufferId      the id of the buffer to be fetched.
+     * @param handle        the native handle of the fetched buffer.
+     *
+     * @return OK when a buffer is successfully fetched.
+     *         NO_MEMORY when there is no memory.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus fetch(
+            ConnectionId connectionId,
+            TransactionId transactionId,
+            BufferId bufferId,
+            const native_handle_t** handle);
+
+    /**
+     * Makes a connection to the buffer pool. The buffer pool client uses the
+     * created connection in order to communicate with the buffer pool. An
+     * FMQ for buffer status message is also created for the client.
+     *
+     * @param observer      client observer for buffer invalidation
+     * @param local         true when a connection request comes from local process,
+     *                      false otherwise.
+     * @param connection    created connection
+     * @param pConnectionId the id of the created connection
+     * @param pMsgId        the id of the recent buffer pool message
+     * @param statusDescPtr FMQ descriptor for shared buffer status message
+     *                      queue between a buffer pool and the client.
+     * @param invDescPtr    FMQ descriptor for buffer invalidation message
+     *                      queue from a buffer pool to the client.
+     *
+     * @return OK when a connection is successfully made.
+     *         NO_MEMORY when there is no memory.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus connect(
+            const sp<IObserver>& observer,
+            bool local,
+            sp<Connection> *connection, ConnectionId *pConnectionId,
+            uint32_t *pMsgId,
+            const StatusDescriptor** statusDescPtr,
+            const InvalidationDescriptor** invDescPtr);
+
+    /**
+     * Closes the specified connection to the client.
+     *
+     * @param connectionId  the id of the connection.
+     *
+     * @return OK when the connection is closed.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus close(ConnectionId connectionId);
+
+    /**
+     * Processes pending buffer status messages and perfoms periodic cache
+     * cleaning.
+     *
+     * @param clearCache    if clearCache is true, it frees all buffers waiting
+     *                      to be recycled.
+     */
+    void cleanUp(bool clearCache);
+
+    /**
+     * Gets a hidl_death_recipient for remote connection death.
+     */
+    static sp<ConnectionDeathRecipient> getConnectionDeathRecipient();
+
+    static void createInvalidator();
+
+    static void createEvictor();
+
+private:
+    class Impl;
+    std::shared_ptr<Impl> mImpl;
+};
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_ACCESSOR_H
diff --git a/media/bufferpool/aidl/default/AccessorImpl.cpp b/media/bufferpool/aidl/default/AccessorImpl.cpp
new file mode 100644
index 0000000..1d2562e
--- /dev/null
+++ b/media/bufferpool/aidl/default/AccessorImpl.cpp
@@ -0,0 +1,993 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "BufferPoolAccessor2.0"
+//#define LOG_NDEBUG 0
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <time.h>
+#include <unistd.h>
+#include <utils/Log.h>
+#include <thread>
+#include "AccessorImpl.h"
+#include "Connection.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+namespace {
+    static constexpr int64_t kCleanUpDurationUs = 500000; // TODO tune 0.5 sec
+    static constexpr int64_t kLogDurationUs = 5000000; // 5 secs
+
+    static constexpr size_t kMinAllocBytesForEviction = 1024*1024*15;
+    static constexpr size_t kMinBufferCountForEviction = 25;
+    static constexpr size_t kMaxUnusedBufferCount = 64;
+    static constexpr size_t kUnusedBufferCountTarget = kMaxUnusedBufferCount - 16;
+
+    static constexpr nsecs_t kEvictGranularityNs = 1000000000; // 1 sec
+    static constexpr nsecs_t kEvictDurationNs = 5000000000; // 5 secs
+}
+
+// Buffer structure in bufferpool process
+struct InternalBuffer {
+    BufferId mId;
+    size_t mOwnerCount;
+    size_t mTransactionCount;
+    const std::shared_ptr<BufferPoolAllocation> mAllocation;
+    const size_t mAllocSize;
+    const std::vector<uint8_t> mConfig;
+    bool mInvalidated;
+
+    InternalBuffer(
+            BufferId id,
+            const std::shared_ptr<BufferPoolAllocation> &alloc,
+            const size_t allocSize,
+            const std::vector<uint8_t> &allocConfig)
+            : mId(id), mOwnerCount(0), mTransactionCount(0),
+            mAllocation(alloc), mAllocSize(allocSize), mConfig(allocConfig),
+            mInvalidated(false) {}
+
+    const native_handle_t *handle() {
+        return mAllocation->handle();
+    }
+
+    void invalidate() {
+        mInvalidated = true;
+    }
+};
+
+struct TransactionStatus {
+    TransactionId mId;
+    BufferId mBufferId;
+    ConnectionId mSender;
+    ConnectionId mReceiver;
+    BufferStatus mStatus;
+    int64_t mTimestampUs;
+    bool mSenderValidated;
+
+    TransactionStatus(const BufferStatusMessage &message, int64_t timestampUs) {
+        mId = message.transactionId;
+        mBufferId = message.bufferId;
+        mStatus = message.newStatus;
+        mTimestampUs = timestampUs;
+        if (mStatus == BufferStatus::TRANSFER_TO) {
+            mSender = message.connectionId;
+            mReceiver = message.targetConnectionId;
+            mSenderValidated = true;
+        } else {
+            mSender = -1LL;
+            mReceiver = message.connectionId;
+            mSenderValidated = false;
+        }
+    }
+};
+
+// Helper template methods for handling map of set.
+template<class T, class U>
+bool insert(std::map<T, std::set<U>> *mapOfSet, T key, U value) {
+    auto iter = mapOfSet->find(key);
+    if (iter == mapOfSet->end()) {
+        std::set<U> valueSet{value};
+        mapOfSet->insert(std::make_pair(key, valueSet));
+        return true;
+    } else if (iter->second.find(value)  == iter->second.end()) {
+        iter->second.insert(value);
+        return true;
+    }
+    return false;
+}
+
+template<class T, class U>
+bool erase(std::map<T, std::set<U>> *mapOfSet, T key, U value) {
+    bool ret = false;
+    auto iter = mapOfSet->find(key);
+    if (iter != mapOfSet->end()) {
+        if (iter->second.erase(value) > 0) {
+            ret = true;
+        }
+        if (iter->second.size() == 0) {
+            mapOfSet->erase(iter);
+        }
+    }
+    return ret;
+}
+
+template<class T, class U>
+bool contains(std::map<T, std::set<U>> *mapOfSet, T key, U value) {
+    auto iter = mapOfSet->find(key);
+    if (iter != mapOfSet->end()) {
+        auto setIter = iter->second.find(value);
+        return setIter != iter->second.end();
+    }
+    return false;
+}
+
+#ifdef __ANDROID_VNDK__
+static constexpr uint32_t kSeqIdVndkBit = 1U << 31;
+#else
+static constexpr uint32_t kSeqIdVndkBit = 0;
+#endif
+
+static constexpr uint32_t kSeqIdMax = 0x7fffffff;
+uint32_t Accessor::Impl::sSeqId = time(nullptr) & kSeqIdMax;
+
+Accessor::Impl::Impl(
+        const std::shared_ptr<BufferPoolAllocator> &allocator)
+        : mAllocator(allocator), mScheduleEvictTs(0) {}
+
+Accessor::Impl::~Impl() {
+}
+
+ResultStatus Accessor::Impl::connect(
+        const sp<Accessor> &accessor, const sp<IObserver> &observer,
+        sp<Connection> *connection,
+        ConnectionId *pConnectionId,
+        uint32_t *pMsgId,
+        const StatusDescriptor** statusDescPtr,
+        const InvalidationDescriptor** invDescPtr) {
+    sp<Connection> newConnection = new Connection();
+    ResultStatus status = ResultStatus::CRITICAL_ERROR;
+    {
+        std::lock_guard<std::mutex> lock(mBufferPool.mMutex);
+        if (newConnection) {
+            int32_t pid = getpid();
+            ConnectionId id = (int64_t)pid << 32 | sSeqId | kSeqIdVndkBit;
+            status = mBufferPool.mObserver.open(id, statusDescPtr);
+            if (status == ResultStatus::OK) {
+                newConnection->initialize(accessor, id);
+                *connection = newConnection;
+                *pConnectionId = id;
+                *pMsgId = mBufferPool.mInvalidation.mInvalidationId;
+                mBufferPool.mConnectionIds.insert(id);
+                mBufferPool.mInvalidationChannel.getDesc(invDescPtr);
+                mBufferPool.mInvalidation.onConnect(id, observer);
+                if (sSeqId == kSeqIdMax) {
+                   sSeqId = 0;
+                } else {
+                    ++sSeqId;
+                }
+            }
+
+        }
+        mBufferPool.processStatusMessages();
+        mBufferPool.cleanUp();
+        scheduleEvictIfNeeded();
+    }
+    return status;
+}
+
+ResultStatus Accessor::Impl::close(ConnectionId connectionId) {
+    std::lock_guard<std::mutex> lock(mBufferPool.mMutex);
+    ALOGV("connection close %lld: %u", (long long)connectionId, mBufferPool.mInvalidation.mId);
+    mBufferPool.processStatusMessages();
+    mBufferPool.handleClose(connectionId);
+    mBufferPool.mObserver.close(connectionId);
+    mBufferPool.mInvalidation.onClose(connectionId);
+    // Since close# will be called after all works are finished, it is OK to
+    // evict unused buffers.
+    mBufferPool.cleanUp(true);
+    scheduleEvictIfNeeded();
+    return ResultStatus::OK;
+}
+
+ResultStatus Accessor::Impl::allocate(
+        ConnectionId connectionId, const std::vector<uint8_t>& params,
+        BufferId *bufferId, const native_handle_t** handle) {
+    std::unique_lock<std::mutex> lock(mBufferPool.mMutex);
+    mBufferPool.processStatusMessages();
+    ResultStatus status = ResultStatus::OK;
+    if (!mBufferPool.getFreeBuffer(mAllocator, params, bufferId, handle)) {
+        lock.unlock();
+        std::shared_ptr<BufferPoolAllocation> alloc;
+        size_t allocSize;
+        status = mAllocator->allocate(params, &alloc, &allocSize);
+        lock.lock();
+        if (status == ResultStatus::OK) {
+            status = mBufferPool.addNewBuffer(alloc, allocSize, params, bufferId, handle);
+        }
+        ALOGV("create a buffer %d : %u %p",
+              status == ResultStatus::OK, *bufferId, *handle);
+    }
+    if (status == ResultStatus::OK) {
+        // TODO: handle ownBuffer failure
+        mBufferPool.handleOwnBuffer(connectionId, *bufferId);
+    }
+    mBufferPool.cleanUp();
+    scheduleEvictIfNeeded();
+    return status;
+}
+
+ResultStatus Accessor::Impl::fetch(
+        ConnectionId connectionId, TransactionId transactionId,
+        BufferId bufferId, const native_handle_t** handle) {
+    std::lock_guard<std::mutex> lock(mBufferPool.mMutex);
+    mBufferPool.processStatusMessages();
+    auto found = mBufferPool.mTransactions.find(transactionId);
+    if (found != mBufferPool.mTransactions.end() &&
+            contains(&mBufferPool.mPendingTransactions,
+                     connectionId, transactionId)) {
+        if (found->second->mSenderValidated &&
+                found->second->mStatus == BufferStatus::TRANSFER_FROM &&
+                found->second->mBufferId == bufferId) {
+            found->second->mStatus = BufferStatus::TRANSFER_FETCH;
+            auto bufferIt = mBufferPool.mBuffers.find(bufferId);
+            if (bufferIt != mBufferPool.mBuffers.end()) {
+                mBufferPool.mStats.onBufferFetched();
+                *handle = bufferIt->second->handle();
+                return ResultStatus::OK;
+            }
+        }
+    }
+    mBufferPool.cleanUp();
+    scheduleEvictIfNeeded();
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+void Accessor::Impl::cleanUp(bool clearCache) {
+    // transaction timeout, buffer cacheing TTL handling
+    std::lock_guard<std::mutex> lock(mBufferPool.mMutex);
+    mBufferPool.processStatusMessages();
+    mBufferPool.cleanUp(clearCache);
+}
+
+void Accessor::Impl::flush() {
+    std::lock_guard<std::mutex> lock(mBufferPool.mMutex);
+    mBufferPool.processStatusMessages();
+    mBufferPool.flush(shared_from_this());
+}
+
+void Accessor::Impl::handleInvalidateAck() {
+    std::map<ConnectionId, const sp<IObserver>> observers;
+    uint32_t invalidationId;
+    {
+        std::lock_guard<std::mutex> lock(mBufferPool.mMutex);
+        mBufferPool.processStatusMessages();
+        mBufferPool.mInvalidation.onHandleAck(&observers, &invalidationId);
+    }
+    // Do not hold lock for send invalidations
+    size_t deadClients = 0;
+    for (auto it = observers.begin(); it != observers.end(); ++it) {
+        const sp<IObserver> observer = it->second;
+        if (observer) {
+            Return<void> transResult = observer->onMessage(it->first, invalidationId);
+            if (!transResult.isOk()) {
+                ++deadClients;
+            }
+        }
+    }
+    if (deadClients > 0) {
+        ALOGD("During invalidation found %zu dead clients", deadClients);
+    }
+}
+
+bool Accessor::Impl::isValid() {
+    return mBufferPool.isValid();
+}
+
+Accessor::Impl::Impl::BufferPool::BufferPool()
+    : mTimestampUs(getTimestampNow()),
+      mLastCleanUpUs(mTimestampUs),
+      mLastLogUs(mTimestampUs),
+      mSeq(0),
+      mStartSeq(0) {
+    mValid = mInvalidationChannel.isValid();
+}
+
+
+// Statistics helper
+template<typename T, typename S>
+int percentage(T base, S total) {
+    return int(total ? 0.5 + 100. * static_cast<S>(base) / total : 0);
+}
+
+std::atomic<std::uint32_t> Accessor::Impl::BufferPool::Invalidation::sInvSeqId(0);
+
+Accessor::Impl::Impl::BufferPool::~BufferPool() {
+    std::lock_guard<std::mutex> lock(mMutex);
+    ALOGD("Destruction - bufferpool2 %p "
+          "cached: %zu/%zuM, %zu/%d%% in use; "
+          "allocs: %zu, %d%% recycled; "
+          "transfers: %zu, %d%% unfetched",
+          this, mStats.mBuffersCached, mStats.mSizeCached >> 20,
+          mStats.mBuffersInUse, percentage(mStats.mBuffersInUse, mStats.mBuffersCached),
+          mStats.mTotalAllocations, percentage(mStats.mTotalRecycles, mStats.mTotalAllocations),
+          mStats.mTotalTransfers,
+          percentage(mStats.mTotalTransfers - mStats.mTotalFetches, mStats.mTotalTransfers));
+}
+
+void Accessor::Impl::BufferPool::Invalidation::onConnect(
+        ConnectionId conId, const sp<IObserver>& observer) {
+    mAcks[conId] = mInvalidationId; // starts from current invalidationId
+    mObservers.insert(std::make_pair(conId, observer));
+}
+
+void Accessor::Impl::BufferPool::Invalidation::onClose(ConnectionId conId) {
+    mAcks.erase(conId);
+    mObservers.erase(conId);
+}
+
+void Accessor::Impl::BufferPool::Invalidation::onAck(
+        ConnectionId conId,
+        uint32_t msgId) {
+    auto it = mAcks.find(conId);
+    if (it == mAcks.end()) {
+        ALOGW("ACK from inconsistent connection! %lld", (long long)conId);
+        return;
+    }
+    if (isMessageLater(msgId, it->second)) {
+        mAcks[conId] = msgId;
+    }
+}
+
+void Accessor::Impl::BufferPool::Invalidation::onBufferInvalidated(
+        BufferId bufferId,
+        BufferInvalidationChannel &channel) {
+    for (auto it = mPendings.begin(); it != mPendings.end();) {
+        if (it->isInvalidated(bufferId)) {
+            uint32_t msgId = 0;
+            if (it->mNeedsAck) {
+                msgId = ++mInvalidationId;
+                if (msgId == 0) {
+                    // wrap happens
+                    msgId = ++mInvalidationId;
+                }
+            }
+            channel.postInvalidation(msgId, it->mFrom, it->mTo);
+            it = mPendings.erase(it);
+            continue;
+        }
+        ++it;
+    }
+}
+
+void Accessor::Impl::BufferPool::Invalidation::onInvalidationRequest(
+        bool needsAck,
+        uint32_t from,
+        uint32_t to,
+        size_t left,
+        BufferInvalidationChannel &channel,
+        const std::shared_ptr<Accessor::Impl> &impl) {
+        uint32_t msgId = 0;
+    if (needsAck) {
+        msgId = ++mInvalidationId;
+        if (msgId == 0) {
+            // wrap happens
+            msgId = ++mInvalidationId;
+        }
+    }
+    ALOGV("bufferpool2 invalidation requested and queued");
+    if (left == 0) {
+        channel.postInvalidation(msgId, from, to);
+    } else {
+        // TODO: sending hint message?
+        ALOGV("bufferpoo2 invalidation requested and pending");
+        Pending pending(needsAck, from, to, left, impl);
+        mPendings.push_back(pending);
+    }
+    sInvalidator->addAccessor(mId, impl);
+}
+
+void Accessor::Impl::BufferPool::Invalidation::onHandleAck(
+        std::map<ConnectionId, const sp<IObserver>> *observers,
+        uint32_t *invalidationId) {
+    if (mInvalidationId != 0) {
+        *invalidationId = mInvalidationId;
+        std::set<int> deads;
+        for (auto it = mAcks.begin(); it != mAcks.end(); ++it) {
+            if (it->second != mInvalidationId) {
+                const sp<IObserver> observer = mObservers[it->first];
+                if (observer) {
+                    observers->emplace(it->first, observer);
+                    ALOGV("connection %lld will call observer (%u: %u)",
+                          (long long)it->first, it->second, mInvalidationId);
+                    // N.B: onMessage will be called later. ignore possibility of
+                    // onMessage# oneway call being lost.
+                    it->second = mInvalidationId;
+                } else {
+                    ALOGV("bufferpool2 observer died %lld", (long long)it->first);
+                    deads.insert(it->first);
+                }
+            }
+        }
+        if (deads.size() > 0) {
+            for (auto it = deads.begin(); it != deads.end(); ++it) {
+                onClose(*it);
+            }
+        }
+    }
+    if (mPendings.size() == 0) {
+        // All invalidation Ids are synced and no more pending invalidations.
+        sInvalidator->delAccessor(mId);
+    }
+}
+
+bool Accessor::Impl::BufferPool::handleOwnBuffer(
+        ConnectionId connectionId, BufferId bufferId) {
+
+    bool added = insert(&mUsingBuffers, connectionId, bufferId);
+    if (added) {
+        auto iter = mBuffers.find(bufferId);
+        iter->second->mOwnerCount++;
+    }
+    insert(&mUsingConnections, bufferId, connectionId);
+    return added;
+}
+
+bool Accessor::Impl::BufferPool::handleReleaseBuffer(
+        ConnectionId connectionId, BufferId bufferId) {
+    bool deleted = erase(&mUsingBuffers, connectionId, bufferId);
+    if (deleted) {
+        auto iter = mBuffers.find(bufferId);
+        iter->second->mOwnerCount--;
+        if (iter->second->mOwnerCount == 0 &&
+                iter->second->mTransactionCount == 0) {
+            if (!iter->second->mInvalidated) {
+                mStats.onBufferUnused(iter->second->mAllocSize);
+                mFreeBuffers.insert(bufferId);
+            } else {
+                mStats.onBufferUnused(iter->second->mAllocSize);
+                mStats.onBufferEvicted(iter->second->mAllocSize);
+                mBuffers.erase(iter);
+                mInvalidation.onBufferInvalidated(bufferId, mInvalidationChannel);
+            }
+        }
+    }
+    erase(&mUsingConnections, bufferId, connectionId);
+    ALOGV("release buffer %u : %d", bufferId, deleted);
+    return deleted;
+}
+
+bool Accessor::Impl::BufferPool::handleTransferTo(const BufferStatusMessage &message) {
+    auto completed = mCompletedTransactions.find(
+            message.transactionId);
+    if (completed != mCompletedTransactions.end()) {
+        // already completed
+        mCompletedTransactions.erase(completed);
+        return true;
+    }
+    // the buffer should exist and be owned.
+    auto bufferIter = mBuffers.find(message.bufferId);
+    if (bufferIter == mBuffers.end() ||
+            !contains(&mUsingBuffers, message.connectionId, message.bufferId)) {
+        return false;
+    }
+    auto found = mTransactions.find(message.transactionId);
+    if (found != mTransactions.end()) {
+        // transfer_from was received earlier.
+        found->second->mSender = message.connectionId;
+        found->second->mSenderValidated = true;
+        return true;
+    }
+    if (mConnectionIds.find(message.targetConnectionId) == mConnectionIds.end()) {
+        // N.B: it could be fake or receive connection already closed.
+        ALOGD("bufferpool2 %p receiver connection %lld is no longer valid",
+              this, (long long)message.targetConnectionId);
+        return false;
+    }
+    mStats.onBufferSent();
+    mTransactions.insert(std::make_pair(
+            message.transactionId,
+            std::make_unique<TransactionStatus>(message, mTimestampUs)));
+    insert(&mPendingTransactions, message.targetConnectionId,
+           message.transactionId);
+    bufferIter->second->mTransactionCount++;
+    return true;
+}
+
+bool Accessor::Impl::BufferPool::handleTransferFrom(const BufferStatusMessage &message) {
+    auto found = mTransactions.find(message.transactionId);
+    if (found == mTransactions.end()) {
+        // TODO: is it feasible to check ownership here?
+        mStats.onBufferSent();
+        mTransactions.insert(std::make_pair(
+                message.transactionId,
+                std::make_unique<TransactionStatus>(message, mTimestampUs)));
+        insert(&mPendingTransactions, message.connectionId,
+               message.transactionId);
+        auto bufferIter = mBuffers.find(message.bufferId);
+        bufferIter->second->mTransactionCount++;
+    } else {
+        if (message.connectionId == found->second->mReceiver) {
+            found->second->mStatus = BufferStatus::TRANSFER_FROM;
+        }
+    }
+    return true;
+}
+
+bool Accessor::Impl::BufferPool::handleTransferResult(const BufferStatusMessage &message) {
+    auto found = mTransactions.find(message.transactionId);
+    if (found != mTransactions.end()) {
+        bool deleted = erase(&mPendingTransactions, message.connectionId,
+                             message.transactionId);
+        if (deleted) {
+            if (!found->second->mSenderValidated) {
+                mCompletedTransactions.insert(message.transactionId);
+            }
+            auto bufferIter = mBuffers.find(message.bufferId);
+            if (message.newStatus == BufferStatus::TRANSFER_OK) {
+                handleOwnBuffer(message.connectionId, message.bufferId);
+            }
+            bufferIter->second->mTransactionCount--;
+            if (bufferIter->second->mOwnerCount == 0
+                && bufferIter->second->mTransactionCount == 0) {
+                if (!bufferIter->second->mInvalidated) {
+                    mStats.onBufferUnused(bufferIter->second->mAllocSize);
+                    mFreeBuffers.insert(message.bufferId);
+                } else {
+                    mStats.onBufferUnused(bufferIter->second->mAllocSize);
+                    mStats.onBufferEvicted(bufferIter->second->mAllocSize);
+                    mBuffers.erase(bufferIter);
+                    mInvalidation.onBufferInvalidated(message.bufferId, mInvalidationChannel);
+                }
+            }
+            mTransactions.erase(found);
+        }
+        ALOGV("transfer finished %llu %u - %d", (unsigned long long)message.transactionId,
+              message.bufferId, deleted);
+        return deleted;
+    }
+    ALOGV("transfer not found %llu %u", (unsigned long long)message.transactionId,
+          message.bufferId);
+    return false;
+}
+
+void Accessor::Impl::BufferPool::processStatusMessages() {
+    std::vector<BufferStatusMessage> messages;
+    mObserver.getBufferStatusChanges(messages);
+    mTimestampUs = getTimestampNow();
+    for (BufferStatusMessage& message: messages) {
+        bool ret = false;
+        switch (message.newStatus) {
+            case BufferStatus::NOT_USED:
+                ret = handleReleaseBuffer(
+                        message.connectionId, message.bufferId);
+                break;
+            case BufferStatus::USED:
+                // not happening
+                break;
+            case BufferStatus::TRANSFER_TO:
+                ret = handleTransferTo(message);
+                break;
+            case BufferStatus::TRANSFER_FROM:
+                ret = handleTransferFrom(message);
+                break;
+            case BufferStatus::TRANSFER_TIMEOUT:
+                // TODO
+                break;
+            case BufferStatus::TRANSFER_LOST:
+                // TODO
+                break;
+            case BufferStatus::TRANSFER_FETCH:
+                // not happening
+                break;
+            case BufferStatus::TRANSFER_OK:
+            case BufferStatus::TRANSFER_ERROR:
+                ret = handleTransferResult(message);
+                break;
+            case BufferStatus::INVALIDATION_ACK:
+                mInvalidation.onAck(message.connectionId, message.bufferId);
+                ret = true;
+                break;
+        }
+        if (ret == false) {
+            ALOGW("buffer status message processing failure - message : %d connection : %lld",
+                  message.newStatus, (long long)message.connectionId);
+        }
+    }
+    messages.clear();
+}
+
+bool Accessor::Impl::BufferPool::handleClose(ConnectionId connectionId) {
+    // Cleaning buffers
+    auto buffers = mUsingBuffers.find(connectionId);
+    if (buffers != mUsingBuffers.end()) {
+        for (const BufferId& bufferId : buffers->second) {
+            bool deleted = erase(&mUsingConnections, bufferId, connectionId);
+            if (deleted) {
+                auto bufferIter = mBuffers.find(bufferId);
+                bufferIter->second->mOwnerCount--;
+                if (bufferIter->second->mOwnerCount == 0 &&
+                        bufferIter->second->mTransactionCount == 0) {
+                    // TODO: handle freebuffer insert fail
+                    if (!bufferIter->second->mInvalidated) {
+                        mStats.onBufferUnused(bufferIter->second->mAllocSize);
+                        mFreeBuffers.insert(bufferId);
+                    } else {
+                        mStats.onBufferUnused(bufferIter->second->mAllocSize);
+                        mStats.onBufferEvicted(bufferIter->second->mAllocSize);
+                        mBuffers.erase(bufferIter);
+                        mInvalidation.onBufferInvalidated(bufferId, mInvalidationChannel);
+                    }
+                }
+            }
+        }
+        mUsingBuffers.erase(buffers);
+    }
+
+    // Cleaning transactions
+    auto pending = mPendingTransactions.find(connectionId);
+    if (pending != mPendingTransactions.end()) {
+        for (const TransactionId& transactionId : pending->second) {
+            auto iter = mTransactions.find(transactionId);
+            if (iter != mTransactions.end()) {
+                if (!iter->second->mSenderValidated) {
+                    mCompletedTransactions.insert(transactionId);
+                }
+                BufferId bufferId = iter->second->mBufferId;
+                auto bufferIter = mBuffers.find(bufferId);
+                bufferIter->second->mTransactionCount--;
+                if (bufferIter->second->mOwnerCount == 0 &&
+                    bufferIter->second->mTransactionCount == 0) {
+                    // TODO: handle freebuffer insert fail
+                    if (!bufferIter->second->mInvalidated) {
+                        mStats.onBufferUnused(bufferIter->second->mAllocSize);
+                        mFreeBuffers.insert(bufferId);
+                    } else {
+                        mStats.onBufferUnused(bufferIter->second->mAllocSize);
+                        mStats.onBufferEvicted(bufferIter->second->mAllocSize);
+                        mBuffers.erase(bufferIter);
+                        mInvalidation.onBufferInvalidated(bufferId, mInvalidationChannel);
+                    }
+                }
+                mTransactions.erase(iter);
+            }
+        }
+    }
+    mConnectionIds.erase(connectionId);
+    return true;
+}
+
+bool Accessor::Impl::BufferPool::getFreeBuffer(
+        const std::shared_ptr<BufferPoolAllocator> &allocator,
+        const std::vector<uint8_t> &params, BufferId *pId,
+        const native_handle_t** handle) {
+    auto bufferIt = mFreeBuffers.begin();
+    for (;bufferIt != mFreeBuffers.end(); ++bufferIt) {
+        BufferId bufferId = *bufferIt;
+        if (allocator->compatible(params, mBuffers[bufferId]->mConfig)) {
+            break;
+        }
+    }
+    if (bufferIt != mFreeBuffers.end()) {
+        BufferId id = *bufferIt;
+        mFreeBuffers.erase(bufferIt);
+        mStats.onBufferRecycled(mBuffers[id]->mAllocSize);
+        *handle = mBuffers[id]->handle();
+        *pId = id;
+        ALOGV("recycle a buffer %u %p", id, *handle);
+        return true;
+    }
+    return false;
+}
+
+ResultStatus Accessor::Impl::BufferPool::addNewBuffer(
+        const std::shared_ptr<BufferPoolAllocation> &alloc,
+        const size_t allocSize,
+        const std::vector<uint8_t> &params,
+        BufferId *pId,
+        const native_handle_t** handle) {
+
+    BufferId bufferId = mSeq++;
+    if (mSeq == Connection::SYNC_BUFFERID) {
+        mSeq = 0;
+    }
+    std::unique_ptr<InternalBuffer> buffer =
+            std::make_unique<InternalBuffer>(
+                    bufferId, alloc, allocSize, params);
+    if (buffer) {
+        auto res = mBuffers.insert(std::make_pair(
+                bufferId, std::move(buffer)));
+        if (res.second) {
+            mStats.onBufferAllocated(allocSize);
+            *handle = alloc->handle();
+            *pId = bufferId;
+            return ResultStatus::OK;
+        }
+    }
+    return ResultStatus::NO_MEMORY;
+}
+
+void Accessor::Impl::BufferPool::cleanUp(bool clearCache) {
+    if (clearCache || mTimestampUs > mLastCleanUpUs + kCleanUpDurationUs ||
+            mStats.buffersNotInUse() > kMaxUnusedBufferCount) {
+        mLastCleanUpUs = mTimestampUs;
+        if (mTimestampUs > mLastLogUs + kLogDurationUs ||
+                mStats.buffersNotInUse() > kMaxUnusedBufferCount) {
+            mLastLogUs = mTimestampUs;
+            ALOGD("bufferpool2 %p : %zu(%zu size) total buffers - "
+                  "%zu(%zu size) used buffers - %zu/%zu (recycle/alloc) - "
+                  "%zu/%zu (fetch/transfer)",
+                  this, mStats.mBuffersCached, mStats.mSizeCached,
+                  mStats.mBuffersInUse, mStats.mSizeInUse,
+                  mStats.mTotalRecycles, mStats.mTotalAllocations,
+                  mStats.mTotalFetches, mStats.mTotalTransfers);
+        }
+        for (auto freeIt = mFreeBuffers.begin(); freeIt != mFreeBuffers.end();) {
+            if (!clearCache && mStats.buffersNotInUse() <= kUnusedBufferCountTarget &&
+                    (mStats.mSizeCached < kMinAllocBytesForEviction ||
+                     mBuffers.size() < kMinBufferCountForEviction)) {
+                break;
+            }
+            auto it = mBuffers.find(*freeIt);
+            if (it != mBuffers.end() &&
+                    it->second->mOwnerCount == 0 && it->second->mTransactionCount == 0) {
+                mStats.onBufferEvicted(it->second->mAllocSize);
+                mBuffers.erase(it);
+                freeIt = mFreeBuffers.erase(freeIt);
+            } else {
+                ++freeIt;
+                ALOGW("bufferpool2 inconsistent!");
+            }
+        }
+    }
+}
+
+void Accessor::Impl::BufferPool::invalidate(
+        bool needsAck, BufferId from, BufferId to,
+        const std::shared_ptr<Accessor::Impl> &impl) {
+    for (auto freeIt = mFreeBuffers.begin(); freeIt != mFreeBuffers.end();) {
+        if (isBufferInRange(from, to, *freeIt)) {
+            auto it = mBuffers.find(*freeIt);
+            if (it != mBuffers.end() &&
+                it->second->mOwnerCount == 0 && it->second->mTransactionCount == 0) {
+                mStats.onBufferEvicted(it->second->mAllocSize);
+                mBuffers.erase(it);
+                freeIt = mFreeBuffers.erase(freeIt);
+                continue;
+            } else {
+                ALOGW("bufferpool2 inconsistent!");
+            }
+        }
+        ++freeIt;
+    }
+
+    size_t left = 0;
+    for (auto it = mBuffers.begin(); it != mBuffers.end(); ++it) {
+        if (isBufferInRange(from, to, it->first)) {
+            it->second->invalidate();
+            ++left;
+        }
+    }
+    mInvalidation.onInvalidationRequest(needsAck, from, to, left, mInvalidationChannel, impl);
+}
+
+void Accessor::Impl::BufferPool::flush(const std::shared_ptr<Accessor::Impl> &impl) {
+    BufferId from = mStartSeq;
+    BufferId to = mSeq;
+    mStartSeq = mSeq;
+    // TODO: needsAck params 
+    ALOGV("buffer invalidation request bp:%u %u %u", mInvalidation.mId, from, to);
+    if (from != to) {
+        invalidate(true, from, to, impl);
+    }
+}
+
+void Accessor::Impl::invalidatorThread(
+            std::map<uint32_t, const std::weak_ptr<Accessor::Impl>> &accessors,
+            std::mutex &mutex,
+            std::condition_variable &cv,
+            bool &ready) {
+    constexpr uint32_t NUM_SPIN_TO_INCREASE_SLEEP = 1024;
+    constexpr uint32_t NUM_SPIN_TO_LOG = 1024*8;
+    constexpr useconds_t MAX_SLEEP_US = 10000;
+    uint32_t numSpin = 0;
+    useconds_t sleepUs = 1;
+
+    while(true) {
+        std::map<uint32_t, const std::weak_ptr<Accessor::Impl>> copied;
+        {
+            std::unique_lock<std::mutex> lock(mutex);
+            if (!ready) {
+                numSpin = 0;
+                sleepUs = 1;
+                cv.wait(lock);
+            }
+            copied.insert(accessors.begin(), accessors.end());
+        }
+        std::list<ConnectionId> erased;
+        for (auto it = copied.begin(); it != copied.end(); ++it) {
+            const std::shared_ptr<Accessor::Impl> impl = it->second.lock();
+            if (!impl) {
+                erased.push_back(it->first);
+            } else {
+                impl->handleInvalidateAck();
+            }
+        }
+        {
+            std::unique_lock<std::mutex> lock(mutex);
+            for (auto it = erased.begin(); it != erased.end(); ++it) {
+                accessors.erase(*it);
+            }
+            if (accessors.size() == 0) {
+                ready = false;
+            } else {
+                // TODO Use an efficient way to wait over FMQ.
+                // N.B. Since there is not a efficient way to wait over FMQ,
+                // polling over the FMQ is the current way to prevent draining
+                // CPU.
+                lock.unlock();
+                ++numSpin;
+                if (numSpin % NUM_SPIN_TO_INCREASE_SLEEP == 0 &&
+                    sleepUs < MAX_SLEEP_US) {
+                    sleepUs *= 10;
+                }
+                if (numSpin % NUM_SPIN_TO_LOG == 0) {
+                    ALOGW("invalidator thread spinning");
+                }
+                ::usleep(sleepUs);
+            }
+        }
+    }
+}
+
+Accessor::Impl::AccessorInvalidator::AccessorInvalidator() : mReady(false) {
+    std::thread invalidator(
+            invalidatorThread,
+            std::ref(mAccessors),
+            std::ref(mMutex),
+            std::ref(mCv),
+            std::ref(mReady));
+    invalidator.detach();
+}
+
+void Accessor::Impl::AccessorInvalidator::addAccessor(
+        uint32_t accessorId, const std::weak_ptr<Accessor::Impl> &impl) {
+    bool notify = false;
+    std::unique_lock<std::mutex> lock(mMutex);
+    if (mAccessors.find(accessorId) == mAccessors.end()) {
+        if (!mReady) {
+            mReady = true;
+            notify = true;
+        }
+        mAccessors.insert(std::make_pair(accessorId, impl));
+        ALOGV("buffer invalidation added bp:%u %d", accessorId, notify);
+    }
+    lock.unlock();
+    if (notify) {
+        mCv.notify_one();
+    }
+}
+
+void Accessor::Impl::AccessorInvalidator::delAccessor(uint32_t accessorId) {
+    std::lock_guard<std::mutex> lock(mMutex);
+    mAccessors.erase(accessorId);
+    ALOGV("buffer invalidation deleted bp:%u", accessorId);
+    if (mAccessors.size() == 0) {
+        mReady = false;
+    }
+}
+
+std::unique_ptr<Accessor::Impl::AccessorInvalidator> Accessor::Impl::sInvalidator;
+
+void Accessor::Impl::createInvalidator() {
+    if (!sInvalidator) {
+        sInvalidator = std::make_unique<Accessor::Impl::AccessorInvalidator>();
+    }
+}
+
+void Accessor::Impl::evictorThread(
+        std::map<const std::weak_ptr<Accessor::Impl>, nsecs_t, std::owner_less<>> &accessors,
+        std::mutex &mutex,
+        std::condition_variable &cv) {
+    std::list<const std::weak_ptr<Accessor::Impl>> evictList;
+    while (true) {
+        int expired = 0;
+        int evicted = 0;
+        {
+            nsecs_t now = systemTime();
+            std::unique_lock<std::mutex> lock(mutex);
+            if (accessors.size() == 0) {
+                cv.wait(lock);
+            }
+            auto it = accessors.begin();
+            while (it != accessors.end()) {
+                if (now > (it->second + kEvictDurationNs)) {
+                    ++expired;
+                    evictList.push_back(it->first);
+                    it = accessors.erase(it);
+                } else {
+                    ++it;
+                }
+            }
+        }
+        // evict idle accessors;
+        for (auto it = evictList.begin(); it != evictList.end(); ++it) {
+            const std::shared_ptr<Accessor::Impl> accessor = it->lock();
+            if (accessor) {
+                accessor->cleanUp(true);
+                ++evicted;
+            }
+        }
+        if (expired > 0) {
+            ALOGD("evictor expired: %d, evicted: %d", expired, evicted);
+        }
+        evictList.clear();
+        ::usleep(kEvictGranularityNs / 1000);
+    }
+}
+
+Accessor::Impl::AccessorEvictor::AccessorEvictor() {
+    std::thread evictor(
+            evictorThread,
+            std::ref(mAccessors),
+            std::ref(mMutex),
+            std::ref(mCv));
+    evictor.detach();
+}
+
+void Accessor::Impl::AccessorEvictor::addAccessor(
+        const std::weak_ptr<Accessor::Impl> &impl, nsecs_t ts) {
+    std::lock_guard<std::mutex> lock(mMutex);
+    bool notify = mAccessors.empty();
+    auto it = mAccessors.find(impl);
+    if (it == mAccessors.end()) {
+        mAccessors.emplace(impl, ts);
+    } else {
+        it->second = ts;
+    }
+    if (notify) {
+        mCv.notify_one();
+    }
+}
+
+std::unique_ptr<Accessor::Impl::AccessorEvictor> Accessor::Impl::sEvictor;
+
+void Accessor::Impl::createEvictor() {
+    if (!sEvictor) {
+        sEvictor = std::make_unique<Accessor::Impl::AccessorEvictor>();
+    }
+}
+
+void Accessor::Impl::scheduleEvictIfNeeded() {
+    nsecs_t now = systemTime();
+
+    if (now > (mScheduleEvictTs + kEvictGranularityNs)) {
+        mScheduleEvictTs = now;
+        sEvictor->addAccessor(shared_from_this(), now);
+    }
+}
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
diff --git a/media/bufferpool/aidl/default/AccessorImpl.h b/media/bufferpool/aidl/default/AccessorImpl.h
new file mode 100644
index 0000000..3d39941
--- /dev/null
+++ b/media/bufferpool/aidl/default/AccessorImpl.h
@@ -0,0 +1,431 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_ACCESSORIMPL_H
+#define ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_ACCESSORIMPL_H
+
+#include <map>
+#include <set>
+#include <condition_variable>
+#include <utils/Timers.h>
+#include "Accessor.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+struct InternalBuffer;
+struct TransactionStatus;
+
+/**
+ * An implementation of a buffer pool accessor(or a buffer pool implementation.) */
+class Accessor::Impl
+    : public std::enable_shared_from_this<Accessor::Impl> {
+public:
+    Impl(const std::shared_ptr<BufferPoolAllocator> &allocator);
+
+    ~Impl();
+
+    ResultStatus connect(
+            const sp<Accessor> &accessor, const sp<IObserver> &observer,
+            sp<Connection> *connection,
+            ConnectionId *pConnectionId,
+            uint32_t *pMsgId,
+            const StatusDescriptor** statusDescPtr,
+            const InvalidationDescriptor** invDescPtr);
+
+    ResultStatus close(ConnectionId connectionId);
+
+    ResultStatus allocate(ConnectionId connectionId,
+                          const std::vector<uint8_t>& params,
+                          BufferId *bufferId,
+                          const native_handle_t** handle);
+
+    ResultStatus fetch(ConnectionId connectionId,
+                       TransactionId transactionId,
+                       BufferId bufferId,
+                       const native_handle_t** handle);
+
+    void flush();
+
+    void cleanUp(bool clearCache);
+
+    bool isValid();
+
+    void handleInvalidateAck();
+
+    static void createInvalidator();
+
+    static void createEvictor();
+
+private:
+    // ConnectionId = pid : (timestamp_created + seqId)
+    // in order to guarantee uniqueness for each connection
+    static uint32_t sSeqId;
+
+    const std::shared_ptr<BufferPoolAllocator> mAllocator;
+
+    nsecs_t mScheduleEvictTs;
+
+    /**
+     * Buffer pool implementation.
+     *
+     * Handles buffer status messages. Handles buffer allocation/recycling.
+     * Handles buffer transfer between buffer pool clients.
+     */
+    struct BufferPool {
+    private:
+        std::mutex mMutex;
+        int64_t mTimestampUs;
+        int64_t mLastCleanUpUs;
+        int64_t mLastLogUs;
+        BufferId mSeq;
+        BufferId mStartSeq;
+        bool mValid;
+        BufferStatusObserver mObserver;
+        BufferInvalidationChannel mInvalidationChannel;
+
+        std::map<ConnectionId, std::set<BufferId>> mUsingBuffers;
+        std::map<BufferId, std::set<ConnectionId>> mUsingConnections;
+
+        std::map<ConnectionId, std::set<TransactionId>> mPendingTransactions;
+        // Transactions completed before TRANSFER_TO message arrival.
+        // Fetch does not occur for the transactions.
+        // Only transaction id is kept for the transactions in short duration.
+        std::set<TransactionId> mCompletedTransactions;
+        // Currently active(pending) transations' status & information.
+        std::map<TransactionId, std::unique_ptr<TransactionStatus>>
+                mTransactions;
+
+        std::map<BufferId, std::unique_ptr<InternalBuffer>> mBuffers;
+        std::set<BufferId> mFreeBuffers;
+        std::set<ConnectionId> mConnectionIds;
+
+        struct Invalidation {
+            static std::atomic<std::uint32_t> sInvSeqId;
+
+            struct Pending {
+                bool mNeedsAck;
+                uint32_t mFrom;
+                uint32_t mTo;
+                size_t mLeft;
+                const std::weak_ptr<Accessor::Impl> mImpl;
+                Pending(bool needsAck, uint32_t from, uint32_t to, size_t left,
+                        const std::shared_ptr<Accessor::Impl> &impl)
+                        : mNeedsAck(needsAck),
+                          mFrom(from),
+                          mTo(to),
+                          mLeft(left),
+                          mImpl(impl)
+                {}
+
+                bool isInvalidated(uint32_t bufferId) {
+                    return isBufferInRange(mFrom, mTo, bufferId) && --mLeft == 0;
+                }
+            };
+
+            std::list<Pending> mPendings;
+            std::map<ConnectionId, uint32_t> mAcks;
+            std::map<ConnectionId, const sp<IObserver>> mObservers;
+            uint32_t mInvalidationId;
+            uint32_t mId;
+
+            Invalidation() : mInvalidationId(0), mId(sInvSeqId.fetch_add(1)) {}
+
+            void onConnect(ConnectionId conId, const sp<IObserver> &observer);
+
+            void onClose(ConnectionId conId);
+
+            void onAck(ConnectionId conId, uint32_t msgId);
+
+            void onBufferInvalidated(
+                    BufferId bufferId,
+                    BufferInvalidationChannel &channel);
+
+            void onInvalidationRequest(
+                    bool needsAck, uint32_t from, uint32_t to, size_t left,
+                    BufferInvalidationChannel &channel,
+                    const std::shared_ptr<Accessor::Impl> &impl);
+
+            void onHandleAck(
+                    std::map<ConnectionId, const sp<IObserver>> *observers,
+                    uint32_t *invalidationId);
+        } mInvalidation;
+        /// Buffer pool statistics which tracks allocation and transfer statistics.
+        struct Stats {
+            /// Total size of allocations which are used or available to use.
+            /// (bytes or pixels)
+            size_t mSizeCached;
+            /// # of cached buffers which are used or available to use.
+            size_t mBuffersCached;
+            /// Total size of allocations which are currently used. (bytes or pixels)
+            size_t mSizeInUse;
+            /// # of currently used buffers
+            size_t mBuffersInUse;
+
+            /// # of allocations called on bufferpool. (# of fetched from BlockPool)
+            size_t mTotalAllocations;
+            /// # of allocations that were served from the cache.
+            /// (# of allocator alloc prevented)
+            size_t mTotalRecycles;
+            /// # of buffer transfers initiated.
+            size_t mTotalTransfers;
+            /// # of transfers that had to be fetched.
+            size_t mTotalFetches;
+
+            Stats()
+                : mSizeCached(0), mBuffersCached(0), mSizeInUse(0), mBuffersInUse(0),
+                  mTotalAllocations(0), mTotalRecycles(0), mTotalTransfers(0), mTotalFetches(0) {}
+
+            /// # of currently unused buffers
+            size_t buffersNotInUse() const {
+                ALOG_ASSERT(mBuffersCached >= mBuffersInUse);
+                return mBuffersCached - mBuffersInUse;
+            }
+
+            /// A new buffer is allocated on an allocation request.
+            void onBufferAllocated(size_t allocSize) {
+                mSizeCached += allocSize;
+                mBuffersCached++;
+
+                mSizeInUse += allocSize;
+                mBuffersInUse++;
+
+                mTotalAllocations++;
+            }
+
+            /// A buffer is evicted and destroyed.
+            void onBufferEvicted(size_t allocSize) {
+                mSizeCached -= allocSize;
+                mBuffersCached--;
+            }
+
+            /// A buffer is recycled on an allocation request.
+            void onBufferRecycled(size_t allocSize) {
+                mSizeInUse += allocSize;
+                mBuffersInUse++;
+
+                mTotalAllocations++;
+                mTotalRecycles++;
+            }
+
+            /// A buffer is available to be recycled.
+            void onBufferUnused(size_t allocSize) {
+                mSizeInUse -= allocSize;
+                mBuffersInUse--;
+            }
+
+            /// A buffer transfer is initiated.
+            void onBufferSent() {
+                mTotalTransfers++;
+            }
+
+            /// A buffer fetch is invoked by a buffer transfer.
+            void onBufferFetched() {
+                mTotalFetches++;
+            }
+        } mStats;
+
+        bool isValid() {
+            return mValid;
+        }
+
+        void invalidate(bool needsAck, BufferId from, BufferId to,
+                        const std::shared_ptr<Accessor::Impl> &impl);
+
+        static void createInvalidator();
+
+    public:
+        /** Creates a buffer pool. */
+        BufferPool();
+
+        /** Destroys a buffer pool. */
+        ~BufferPool();
+
+        /**
+         * Processes all pending buffer status messages, and returns the result.
+         * Each status message is handled by methods with 'handle' prefix.
+         */
+        void processStatusMessages();
+
+        /**
+         * Handles a buffer being owned by a connection.
+         *
+         * @param connectionId  the id of the buffer owning connection.
+         * @param bufferId      the id of the buffer.
+         *
+         * @return {@code true} when the buffer is owned,
+         *         {@code false} otherwise.
+         */
+        bool handleOwnBuffer(ConnectionId connectionId, BufferId bufferId);
+
+        /**
+         * Handles a buffer being released by a connection.
+         *
+         * @param connectionId  the id of the buffer owning connection.
+         * @param bufferId      the id of the buffer.
+         *
+         * @return {@code true} when the buffer ownership is released,
+         *         {@code false} otherwise.
+         */
+        bool handleReleaseBuffer(ConnectionId connectionId, BufferId bufferId);
+
+        /**
+         * Handles a transfer transaction start message from the sender.
+         *
+         * @param message   a buffer status message for the transaction.
+         *
+         * @result {@code true} when transfer_to message is acknowledged,
+         *         {@code false} otherwise.
+         */
+        bool handleTransferTo(const BufferStatusMessage &message);
+
+        /**
+         * Handles a transfer transaction being acked by the receiver.
+         *
+         * @param message   a buffer status message for the transaction.
+         *
+         * @result {@code true} when transfer_from message is acknowledged,
+         *         {@code false} otherwise.
+         */
+        bool handleTransferFrom(const BufferStatusMessage &message);
+
+        /**
+         * Handles a transfer transaction result message from the receiver.
+         *
+         * @param message   a buffer status message for the transaction.
+         *
+         * @result {@code true} when the exisitng transaction is finished,
+         *         {@code false} otherwise.
+         */
+        bool handleTransferResult(const BufferStatusMessage &message);
+
+        /**
+         * Handles a connection being closed, and returns the result. All the
+         * buffers and transactions owned by the connection will be cleaned up.
+         * The related FMQ will be cleaned up too.
+         *
+         * @param connectionId  the id of the connection.
+         *
+         * @result {@code true} when the connection existed,
+         *         {@code false} otherwise.
+         */
+        bool handleClose(ConnectionId connectionId);
+
+        /**
+         * Recycles a existing free buffer if it is possible.
+         *
+         * @param allocator the buffer allocator
+         * @param params    the allocation parameters.
+         * @param pId       the id of the recycled buffer.
+         * @param handle    the native handle of the recycled buffer.
+         *
+         * @return {@code true} when a buffer is recycled, {@code false}
+         *         otherwise.
+         */
+        bool getFreeBuffer(
+                const std::shared_ptr<BufferPoolAllocator> &allocator,
+                const std::vector<uint8_t> &params,
+                BufferId *pId, const native_handle_t **handle);
+
+        /**
+         * Adds a newly allocated buffer to bufferpool.
+         *
+         * @param alloc     the newly allocated buffer.
+         * @param allocSize the size of the newly allocated buffer.
+         * @param params    the allocation parameters.
+         * @param pId       the buffer id for the newly allocated buffer.
+         * @param handle    the native handle for the newly allocated buffer.
+         *
+         * @return OK when an allocation is successfully allocated.
+         *         NO_MEMORY when there is no memory.
+         *         CRITICAL_ERROR otherwise.
+         */
+        ResultStatus addNewBuffer(
+                const std::shared_ptr<BufferPoolAllocation> &alloc,
+                const size_t allocSize,
+                const std::vector<uint8_t> &params,
+                BufferId *pId,
+                const native_handle_t **handle);
+
+        /**
+         * Processes pending buffer status messages and performs periodic cache
+         * cleaning.
+         *
+         * @param clearCache    if clearCache is true, it frees all buffers
+         *                      waiting to be recycled.
+         */
+        void cleanUp(bool clearCache = false);
+
+        /**
+         * Processes pending buffer status messages and invalidate all current
+         * free buffers. Active buffers are invalidated after being inactive.
+         */
+        void flush(const std::shared_ptr<Accessor::Impl> &impl);
+
+        friend class Accessor::Impl;
+    } mBufferPool;
+
+    struct  AccessorInvalidator {
+        std::map<uint32_t, const std::weak_ptr<Accessor::Impl>> mAccessors;
+        std::mutex mMutex;
+        std::condition_variable mCv;
+        bool mReady;
+
+        AccessorInvalidator();
+        void addAccessor(uint32_t accessorId, const std::weak_ptr<Accessor::Impl> &impl);
+        void delAccessor(uint32_t accessorId);
+    };
+
+    static std::unique_ptr<AccessorInvalidator> sInvalidator;
+
+    static void invalidatorThread(
+        std::map<uint32_t, const std::weak_ptr<Accessor::Impl>> &accessors,
+        std::mutex &mutex,
+        std::condition_variable &cv,
+        bool &ready);
+
+    struct AccessorEvictor {
+        std::map<const std::weak_ptr<Accessor::Impl>, nsecs_t, std::owner_less<>> mAccessors;
+        std::mutex mMutex;
+        std::condition_variable mCv;
+
+        AccessorEvictor();
+        void addAccessor(const std::weak_ptr<Accessor::Impl> &impl, nsecs_t ts);
+    };
+
+    static std::unique_ptr<AccessorEvictor> sEvictor;
+
+    static void evictorThread(
+        std::map<const std::weak_ptr<Accessor::Impl>, nsecs_t, std::owner_less<>> &accessors,
+        std::mutex &mutex,
+        std::condition_variable &cv);
+
+    void scheduleEvictIfNeeded();
+
+};
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace ufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_ACCESSORIMPL_H
diff --git a/media/bufferpool/aidl/default/BufferPoolClient.cpp b/media/bufferpool/aidl/default/BufferPoolClient.cpp
new file mode 100644
index 0000000..cda23ff
--- /dev/null
+++ b/media/bufferpool/aidl/default/BufferPoolClient.cpp
@@ -0,0 +1,876 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "BufferPoolClient"
+//#define LOG_NDEBUG 0
+
+#include <thread>
+#include <utils/Log.h>
+#include "BufferPoolClient.h"
+#include "Connection.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+static constexpr int64_t kReceiveTimeoutUs = 2000000; // 2s
+static constexpr int kPostMaxRetry = 3;
+static constexpr int kCacheTtlUs = 1000000; // TODO: tune
+static constexpr size_t kMaxCachedBufferCount = 64;
+static constexpr size_t kCachedBufferCountTarget = kMaxCachedBufferCount - 16;
+
+class BufferPoolClient::Impl
+        : public std::enable_shared_from_this<BufferPoolClient::Impl> {
+public:
+    explicit Impl(const sp<Accessor> &accessor, const sp<IObserver> &observer);
+
+    explicit Impl(const sp<IAccessor> &accessor, const sp<IObserver> &observer);
+
+    bool isValid() {
+        return mValid;
+    }
+
+    bool isLocal() {
+        return mValid && mLocal;
+    }
+
+    ConnectionId getConnectionId() {
+        return mConnectionId;
+    }
+
+    sp<IAccessor> &getAccessor() {
+        return mAccessor;
+    }
+
+    bool isActive(int64_t *lastTransactionUs, bool clearCache);
+
+    void receiveInvalidation(uint32_t msgID);
+
+    ResultStatus flush();
+
+    ResultStatus allocate(const std::vector<uint8_t> &params,
+                          native_handle_t **handle,
+                          std::shared_ptr<BufferPoolData> *buffer);
+
+    ResultStatus receive(
+            TransactionId transactionId, BufferId bufferId,
+            int64_t timestampUs,
+            native_handle_t **handle, std::shared_ptr<BufferPoolData> *buffer);
+
+    void postBufferRelease(BufferId bufferId);
+
+    bool postSend(
+            BufferId bufferId, ConnectionId receiver,
+            TransactionId *transactionId, int64_t *timestampUs);
+private:
+
+    bool postReceive(
+            BufferId bufferId, TransactionId transactionId,
+            int64_t timestampUs);
+
+    bool postReceiveResult(
+            BufferId bufferId, TransactionId transactionId, bool result, bool *needsSync);
+
+    void trySyncFromRemote();
+
+    bool syncReleased(uint32_t msgId = 0);
+
+    void evictCaches(bool clearCache = false);
+
+    void invalidateBuffer(BufferId id);
+
+    void invalidateRange(BufferId from, BufferId to);
+
+    ResultStatus allocateBufferHandle(
+            const std::vector<uint8_t>& params, BufferId *bufferId,
+            native_handle_t **handle);
+
+    ResultStatus fetchBufferHandle(
+            TransactionId transactionId, BufferId bufferId,
+            native_handle_t **handle);
+
+    struct BlockPoolDataDtor;
+    struct ClientBuffer;
+
+    bool mLocal;
+    bool mValid;
+    sp<IAccessor> mAccessor;
+    sp<Connection> mLocalConnection;
+    sp<IConnection> mRemoteConnection;
+    uint32_t mSeqId;
+    ConnectionId mConnectionId;
+    int64_t mLastEvictCacheUs;
+    std::unique_ptr<BufferInvalidationListener> mInvalidationListener;
+
+    // CachedBuffers
+    struct BufferCache {
+        std::mutex mLock;
+        bool mCreating;
+        std::condition_variable mCreateCv;
+        std::map<BufferId, std::unique_ptr<ClientBuffer>> mBuffers;
+        int mActive;
+        int64_t mLastChangeUs;
+
+        BufferCache() : mCreating(false), mActive(0), mLastChangeUs(getTimestampNow()) {}
+
+        void incActive_l() {
+            ++mActive;
+            mLastChangeUs = getTimestampNow();
+        }
+
+        void decActive_l() {
+            --mActive;
+            mLastChangeUs = getTimestampNow();
+        }
+
+        int cachedBufferCount() const {
+            return mBuffers.size() - mActive;
+        }
+    } mCache;
+
+    // FMQ - release notifier
+    struct ReleaseCache {
+        std::mutex mLock;
+        // TODO: use only one list?(using one list may dealy sending messages?)
+        std::list<BufferId> mReleasingIds;
+        std::list<BufferId> mReleasedIds;
+        uint32_t mInvalidateId; // TODO: invalidation ACK to bufferpool
+        bool mInvalidateAck;
+        std::unique_ptr<BufferStatusChannel> mStatusChannel;
+
+        ReleaseCache() : mInvalidateId(0), mInvalidateAck(true) {}
+    } mReleasing;
+
+    // This lock is held during synchronization from remote side.
+    // In order to minimize remote calls and locking durtaion, this lock is held
+    // by best effort approach using try_lock().
+    std::mutex mRemoteSyncLock;
+};
+
+struct BufferPoolClient::Impl::BlockPoolDataDtor {
+    BlockPoolDataDtor(const std::shared_ptr<BufferPoolClient::Impl> &impl)
+            : mImpl(impl) {}
+
+    void operator()(BufferPoolData *buffer) {
+        BufferId id = buffer->mId;
+        delete buffer;
+
+        auto impl = mImpl.lock();
+        if (impl && impl->isValid()) {
+            impl->postBufferRelease(id);
+        }
+    }
+    const std::weak_ptr<BufferPoolClient::Impl> mImpl;
+};
+
+struct BufferPoolClient::Impl::ClientBuffer {
+private:
+    int64_t mExpireUs;
+    bool mHasCache;
+    ConnectionId mConnectionId;
+    BufferId mId;
+    native_handle_t *mHandle;
+    std::weak_ptr<BufferPoolData> mCache;
+
+    void updateExpire() {
+        mExpireUs = getTimestampNow() + kCacheTtlUs;
+    }
+
+public:
+    ClientBuffer(
+            ConnectionId connectionId, BufferId id, native_handle_t *handle)
+            : mHasCache(false), mConnectionId(connectionId),
+              mId(id), mHandle(handle) {
+        mExpireUs = getTimestampNow() + kCacheTtlUs;
+    }
+
+    ~ClientBuffer() {
+        if (mHandle) {
+            native_handle_close(mHandle);
+            native_handle_delete(mHandle);
+        }
+    }
+
+    BufferId id() const {
+        return mId;
+    }
+
+    bool expire() const {
+        int64_t now = getTimestampNow();
+        return now >= mExpireUs;
+    }
+
+    bool hasCache() const {
+        return mHasCache;
+    }
+
+    std::shared_ptr<BufferPoolData> fetchCache(native_handle_t **pHandle) {
+        if (mHasCache) {
+            std::shared_ptr<BufferPoolData> cache = mCache.lock();
+            if (cache) {
+                *pHandle = mHandle;
+            }
+            return cache;
+        }
+        return nullptr;
+    }
+
+    std::shared_ptr<BufferPoolData> createCache(
+            const std::shared_ptr<BufferPoolClient::Impl> &impl,
+            native_handle_t **pHandle) {
+        if (!mHasCache) {
+            // Allocates a raw ptr in order to avoid sending #postBufferRelease
+            // from deleter, in case of native_handle_clone failure.
+            BufferPoolData *ptr = new BufferPoolData(mConnectionId, mId);
+            if (ptr) {
+                std::shared_ptr<BufferPoolData> cache(ptr, BlockPoolDataDtor(impl));
+                if (cache) {
+                    mCache = cache;
+                    mHasCache = true;
+                    *pHandle = mHandle;
+                    return cache;
+                }
+            }
+            if (ptr) {
+                delete ptr;
+            }
+        }
+        return nullptr;
+    }
+
+    bool onCacheRelease() {
+        if (mHasCache) {
+            // TODO: verify mCache is not valid;
+            updateExpire();
+            mHasCache = false;
+            return true;
+        }
+        return false;
+    }
+};
+
+BufferPoolClient::Impl::Impl(const sp<Accessor> &accessor, const sp<IObserver> &observer)
+    : mLocal(true), mValid(false), mAccessor(accessor), mSeqId(0),
+      mLastEvictCacheUs(getTimestampNow()) {
+    const StatusDescriptor *statusDesc;
+    const InvalidationDescriptor *invDesc;
+    ResultStatus status = accessor->connect(
+            observer, true,
+            &mLocalConnection, &mConnectionId, &mReleasing.mInvalidateId,
+            &statusDesc, &invDesc);
+    if (status == ResultStatus::OK) {
+        mReleasing.mStatusChannel =
+                std::make_unique<BufferStatusChannel>(*statusDesc);
+        mInvalidationListener =
+                std::make_unique<BufferInvalidationListener>(*invDesc);
+        mValid = mReleasing.mStatusChannel &&
+                mReleasing.mStatusChannel->isValid() &&
+                mInvalidationListener &&
+                mInvalidationListener->isValid();
+    }
+}
+
+BufferPoolClient::Impl::Impl(const sp<IAccessor> &accessor, const sp<IObserver> &observer)
+    : mLocal(false), mValid(false), mAccessor(accessor), mSeqId(0),
+      mLastEvictCacheUs(getTimestampNow()) {
+    bool valid = false;
+    sp<IConnection>& outConnection = mRemoteConnection;
+    ConnectionId& id = mConnectionId;
+    uint32_t& outMsgId = mReleasing.mInvalidateId;
+    std::unique_ptr<BufferStatusChannel>& outChannel =
+            mReleasing.mStatusChannel;
+    std::unique_ptr<BufferInvalidationListener>& outObserver =
+            mInvalidationListener;
+    Return<void> transResult = accessor->connect(
+            observer,
+            [&valid, &outConnection, &id, &outMsgId, &outChannel, &outObserver]
+            (ResultStatus status, sp<IConnection> connection,
+             ConnectionId connectionId, uint32_t msgId,
+             const StatusDescriptor& statusDesc,
+             const InvalidationDescriptor& invDesc) {
+                if (status == ResultStatus::OK) {
+                    outConnection = connection;
+                    id = connectionId;
+                    outMsgId = msgId;
+                    outChannel = std::make_unique<BufferStatusChannel>(statusDesc);
+                    outObserver = std::make_unique<BufferInvalidationListener>(invDesc);
+                    if (outChannel && outChannel->isValid() &&
+                        outObserver && outObserver->isValid()) {
+                        valid = true;
+                    }
+                }
+            });
+    mValid = transResult.isOk() && valid;
+}
+
+bool BufferPoolClient::Impl::isActive(int64_t *lastTransactionUs, bool clearCache) {
+    bool active = false;
+    {
+        std::lock_guard<std::mutex> lock(mCache.mLock);
+        syncReleased();
+        evictCaches(clearCache);
+        *lastTransactionUs = mCache.mLastChangeUs;
+        active = mCache.mActive > 0;
+    }
+    if (mValid && mLocal && mLocalConnection) {
+        mLocalConnection->cleanUp(clearCache);
+        return true;
+    }
+    return active;
+}
+
+void BufferPoolClient::Impl::receiveInvalidation(uint32_t messageId) {
+    std::lock_guard<std::mutex> lock(mCache.mLock);
+    syncReleased(messageId);
+    // TODO: evict cache required?
+}
+
+ResultStatus BufferPoolClient::Impl::flush() {
+    if (!mLocal || !mLocalConnection || !mValid) {
+        return ResultStatus::CRITICAL_ERROR;
+    }
+    {
+        std::unique_lock<std::mutex> lock(mCache.mLock);
+        syncReleased();
+        evictCaches();
+        return mLocalConnection->flush();
+    }
+}
+
+ResultStatus BufferPoolClient::Impl::allocate(
+        const std::vector<uint8_t> &params,
+        native_handle_t **pHandle,
+        std::shared_ptr<BufferPoolData> *buffer) {
+    if (!mLocal || !mLocalConnection || !mValid) {
+        return ResultStatus::CRITICAL_ERROR;
+    }
+    BufferId bufferId;
+    native_handle_t *handle = nullptr;
+    buffer->reset();
+    ResultStatus status = allocateBufferHandle(params, &bufferId, &handle);
+    if (status == ResultStatus::OK) {
+        if (handle) {
+            std::unique_lock<std::mutex> lock(mCache.mLock);
+            syncReleased();
+            evictCaches();
+            auto cacheIt = mCache.mBuffers.find(bufferId);
+            if (cacheIt != mCache.mBuffers.end()) {
+                // TODO: verify it is recycled. (not having active ref)
+                mCache.mBuffers.erase(cacheIt);
+            }
+            auto clientBuffer = std::make_unique<ClientBuffer>(
+                    mConnectionId, bufferId, handle);
+            if (clientBuffer) {
+                auto result = mCache.mBuffers.insert(std::make_pair(
+                        bufferId, std::move(clientBuffer)));
+                if (result.second) {
+                    *buffer = result.first->second->createCache(
+                            shared_from_this(), pHandle);
+                    if (*buffer) {
+                        mCache.incActive_l();
+                    }
+                }
+            }
+        }
+        if (!*buffer) {
+            ALOGV("client cache creation failure %d: %lld",
+                  handle != nullptr, (long long)mConnectionId);
+            status = ResultStatus::NO_MEMORY;
+            postBufferRelease(bufferId);
+        }
+    }
+    return status;
+}
+
+ResultStatus BufferPoolClient::Impl::receive(
+        TransactionId transactionId, BufferId bufferId, int64_t timestampUs,
+        native_handle_t **pHandle,
+        std::shared_ptr<BufferPoolData> *buffer) {
+    if (!mValid) {
+        return ResultStatus::CRITICAL_ERROR;
+    }
+    if (timestampUs != 0) {
+        timestampUs += kReceiveTimeoutUs;
+    }
+    if (!postReceive(bufferId, transactionId, timestampUs)) {
+        return ResultStatus::CRITICAL_ERROR;
+    }
+    ResultStatus status = ResultStatus::CRITICAL_ERROR;
+    buffer->reset();
+    while(1) {
+        std::unique_lock<std::mutex> lock(mCache.mLock);
+        syncReleased();
+        evictCaches();
+        auto cacheIt = mCache.mBuffers.find(bufferId);
+        if (cacheIt != mCache.mBuffers.end()) {
+            if (cacheIt->second->hasCache()) {
+                *buffer = cacheIt->second->fetchCache(pHandle);
+                if (!*buffer) {
+                    // check transfer time_out
+                    lock.unlock();
+                    std::this_thread::yield();
+                    continue;
+                }
+                ALOGV("client receive from reference %lld", (long long)mConnectionId);
+                break;
+            } else {
+                *buffer = cacheIt->second->createCache(shared_from_this(), pHandle);
+                if (*buffer) {
+                    mCache.incActive_l();
+                }
+                ALOGV("client receive from cache %lld", (long long)mConnectionId);
+                break;
+            }
+        } else {
+            if (!mCache.mCreating) {
+                mCache.mCreating = true;
+                lock.unlock();
+                native_handle_t* handle = nullptr;
+                status = fetchBufferHandle(transactionId, bufferId, &handle);
+                lock.lock();
+                if (status == ResultStatus::OK) {
+                    if (handle) {
+                        auto clientBuffer = std::make_unique<ClientBuffer>(
+                                mConnectionId, bufferId, handle);
+                        if (clientBuffer) {
+                            auto result = mCache.mBuffers.insert(
+                                    std::make_pair(bufferId, std::move(
+                                            clientBuffer)));
+                            if (result.second) {
+                                *buffer = result.first->second->createCache(
+                                        shared_from_this(), pHandle);
+                                if (*buffer) {
+                                    mCache.incActive_l();
+                                }
+                            }
+                        }
+                    }
+                    if (!*buffer) {
+                        status = ResultStatus::NO_MEMORY;
+                    }
+                }
+                mCache.mCreating = false;
+                lock.unlock();
+                mCache.mCreateCv.notify_all();
+                break;
+            }
+            mCache.mCreateCv.wait(lock);
+        }
+    }
+    bool needsSync = false;
+    bool posted = postReceiveResult(bufferId, transactionId,
+                                      *buffer ? true : false, &needsSync);
+    ALOGV("client receive %lld - %u : %s (%d)", (long long)mConnectionId, bufferId,
+          *buffer ? "ok" : "fail", posted);
+    if (mValid && mLocal && mLocalConnection) {
+        mLocalConnection->cleanUp(false);
+    }
+    if (needsSync && mRemoteConnection) {
+        trySyncFromRemote();
+    }
+    if (*buffer) {
+        if (!posted) {
+            buffer->reset();
+            return ResultStatus::CRITICAL_ERROR;
+        }
+        return ResultStatus::OK;
+    }
+    return status;
+}
+
+
+void BufferPoolClient::Impl::postBufferRelease(BufferId bufferId) {
+    std::lock_guard<std::mutex> lock(mReleasing.mLock);
+    mReleasing.mReleasingIds.push_back(bufferId);
+    mReleasing.mStatusChannel->postBufferRelease(
+            mConnectionId, mReleasing.mReleasingIds, mReleasing.mReleasedIds);
+}
+
+// TODO: revise ad-hoc posting data structure
+bool BufferPoolClient::Impl::postSend(
+        BufferId bufferId, ConnectionId receiver,
+        TransactionId *transactionId, int64_t *timestampUs) {
+    {
+        // TODO: don't need to call syncReleased every time
+        std::lock_guard<std::mutex> lock(mCache.mLock);
+        syncReleased();
+    }
+    bool ret = false;
+    bool needsSync = false;
+    {
+        std::lock_guard<std::mutex> lock(mReleasing.mLock);
+        *timestampUs = getTimestampNow();
+        *transactionId = (mConnectionId << 32) | mSeqId++;
+        // TODO: retry, add timeout, target?
+        ret =  mReleasing.mStatusChannel->postBufferStatusMessage(
+                *transactionId, bufferId, BufferStatus::TRANSFER_TO, mConnectionId,
+                receiver, mReleasing.mReleasingIds, mReleasing.mReleasedIds);
+        needsSync = !mLocal && mReleasing.mStatusChannel->needsSync();
+    }
+    if (mValid && mLocal && mLocalConnection) {
+        mLocalConnection->cleanUp(false);
+    }
+    if (needsSync && mRemoteConnection) {
+        trySyncFromRemote();
+    }
+    return ret;
+}
+
+bool BufferPoolClient::Impl::postReceive(
+        BufferId bufferId, TransactionId transactionId, int64_t timestampUs) {
+    for (int i = 0; i < kPostMaxRetry; ++i) {
+        std::unique_lock<std::mutex> lock(mReleasing.mLock);
+        int64_t now = getTimestampNow();
+        if (timestampUs == 0 || now < timestampUs) {
+            bool result = mReleasing.mStatusChannel->postBufferStatusMessage(
+                    transactionId, bufferId, BufferStatus::TRANSFER_FROM,
+                    mConnectionId, -1, mReleasing.mReleasingIds,
+                    mReleasing.mReleasedIds);
+            if (result) {
+                return true;
+            }
+            lock.unlock();
+            std::this_thread::yield();
+        } else {
+            mReleasing.mStatusChannel->postBufferStatusMessage(
+                    transactionId, bufferId, BufferStatus::TRANSFER_TIMEOUT,
+                    mConnectionId, -1, mReleasing.mReleasingIds,
+                    mReleasing.mReleasedIds);
+            return false;
+        }
+    }
+    return false;
+}
+
+bool BufferPoolClient::Impl::postReceiveResult(
+        BufferId bufferId, TransactionId transactionId, bool result, bool *needsSync) {
+    std::lock_guard<std::mutex> lock(mReleasing.mLock);
+    // TODO: retry, add timeout
+    bool ret = mReleasing.mStatusChannel->postBufferStatusMessage(
+            transactionId, bufferId,
+            result ? BufferStatus::TRANSFER_OK : BufferStatus::TRANSFER_ERROR,
+            mConnectionId, -1, mReleasing.mReleasingIds,
+            mReleasing.mReleasedIds);
+    *needsSync = !mLocal && mReleasing.mStatusChannel->needsSync();
+    return ret;
+}
+
+void BufferPoolClient::Impl::trySyncFromRemote() {
+    if (mRemoteSyncLock.try_lock()) {
+        bool needsSync = false;
+        {
+            std::lock_guard<std::mutex> lock(mReleasing.mLock);
+            needsSync = mReleasing.mStatusChannel->needsSync();
+        }
+        if (needsSync) {
+            TransactionId transactionId = (mConnectionId << 32);
+            BufferId bufferId = Connection::SYNC_BUFFERID;
+            Return<void> transResult = mRemoteConnection->fetch(
+                    transactionId, bufferId,
+                    []
+                    (ResultStatus outStatus, Buffer outBuffer) {
+                        (void) outStatus;
+                        (void) outBuffer;
+                    });
+            if (!transResult.isOk()) {
+                ALOGD("sync from client %lld failed: bufferpool process died.",
+                      (long long)mConnectionId);
+            }
+        }
+        mRemoteSyncLock.unlock();
+    }
+}
+
+// should have mCache.mLock
+bool BufferPoolClient::Impl::syncReleased(uint32_t messageId) {
+    bool cleared = false;
+    {
+        std::lock_guard<std::mutex> lock(mReleasing.mLock);
+        if (mReleasing.mReleasingIds.size() > 0) {
+            mReleasing.mStatusChannel->postBufferRelease(
+                    mConnectionId, mReleasing.mReleasingIds,
+                    mReleasing.mReleasedIds);
+        }
+        if (mReleasing.mReleasedIds.size() > 0) {
+            for (BufferId& id: mReleasing.mReleasedIds) {
+                ALOGV("client release buffer %lld - %u", (long long)mConnectionId, id);
+                auto found = mCache.mBuffers.find(id);
+                if (found != mCache.mBuffers.end()) {
+                    if (found->second->onCacheRelease()) {
+                        mCache.decActive_l();
+                    } else {
+                        // should not happen!
+                        ALOGW("client %lld cache release status inconsitent!",
+                            (long long)mConnectionId);
+                    }
+                } else {
+                    // should not happen!
+                    ALOGW("client %lld cache status inconsitent!", (long long)mConnectionId);
+                }
+            }
+            mReleasing.mReleasedIds.clear();
+            cleared = true;
+        }
+    }
+    std::vector<BufferInvalidationMessage> invalidations;
+    mInvalidationListener->getInvalidations(invalidations);
+    uint32_t lastMsgId = 0;
+    if (invalidations.size() > 0) {
+        for (auto it = invalidations.begin(); it != invalidations.end(); ++it) {
+            if (it->messageId != 0) {
+                lastMsgId = it->messageId;
+            }
+            if (it->fromBufferId == it->toBufferId) {
+                // TODO: handle fromBufferId = UINT32_MAX
+                invalidateBuffer(it->fromBufferId);
+            } else {
+                invalidateRange(it->fromBufferId, it->toBufferId);
+            }
+        }
+    }
+    {
+        std::lock_guard<std::mutex> lock(mReleasing.mLock);
+        if (lastMsgId != 0) {
+            if (isMessageLater(lastMsgId, mReleasing.mInvalidateId)) {
+                mReleasing.mInvalidateId = lastMsgId;
+                mReleasing.mInvalidateAck = false;
+            }
+        } else if (messageId != 0) {
+            // messages are drained.
+            if (isMessageLater(messageId, mReleasing.mInvalidateId)) {
+                mReleasing.mInvalidateId = messageId;
+                mReleasing.mInvalidateAck = true;
+            }
+        }
+        if (!mReleasing.mInvalidateAck) {
+            // post ACK
+            mReleasing.mStatusChannel->postBufferInvalidateAck(
+                    mConnectionId,
+                    mReleasing.mInvalidateId, &mReleasing.mInvalidateAck);
+            ALOGV("client %lld invalidateion ack (%d) %u",
+                (long long)mConnectionId,
+                mReleasing.mInvalidateAck, mReleasing.mInvalidateId);
+        }
+    }
+    return cleared;
+}
+
+// should have mCache.mLock
+void BufferPoolClient::Impl::evictCaches(bool clearCache) {
+    int64_t now = getTimestampNow();
+    if (now >= mLastEvictCacheUs + kCacheTtlUs ||
+            clearCache || mCache.cachedBufferCount() > kMaxCachedBufferCount) {
+        size_t evicted = 0;
+        for (auto it = mCache.mBuffers.begin(); it != mCache.mBuffers.end();) {
+            if (!it->second->hasCache() && (it->second->expire() ||
+                        clearCache || mCache.cachedBufferCount() > kCachedBufferCountTarget)) {
+                it = mCache.mBuffers.erase(it);
+                ++evicted;
+            } else {
+                ++it;
+            }
+        }
+        ALOGV("cache count %lld : total %zu, active %d, evicted %zu",
+              (long long)mConnectionId, mCache.mBuffers.size(), mCache.mActive, evicted);
+        mLastEvictCacheUs = now;
+    }
+}
+
+// should have mCache.mLock
+void BufferPoolClient::Impl::invalidateBuffer(BufferId id) {
+    for (auto it = mCache.mBuffers.begin(); it != mCache.mBuffers.end(); ++it) {
+        if (id == it->second->id()) {
+            if (!it->second->hasCache()) {
+                mCache.mBuffers.erase(it);
+                ALOGV("cache invalidated %lld : buffer %u",
+                      (long long)mConnectionId, id);
+            } else {
+                ALOGW("Inconsitent invalidation %lld : activer buffer!! %u",
+                      (long long)mConnectionId, (unsigned int)id);
+            }
+            break;
+        }
+    }
+}
+
+// should have mCache.mLock
+void BufferPoolClient::Impl::invalidateRange(BufferId from, BufferId to) {
+    size_t invalidated = 0;
+    for (auto it = mCache.mBuffers.begin(); it != mCache.mBuffers.end();) {
+        if (!it->second->hasCache()) {
+            BufferId bid = it->second->id();
+            if (from < to) {
+                if (from <= bid && bid < to) {
+                    ++invalidated;
+                    it = mCache.mBuffers.erase(it);
+                    continue;
+                }
+            } else {
+                if (from <= bid || bid < to) {
+                    ++invalidated;
+                    it = mCache.mBuffers.erase(it);
+                    continue;
+                }
+            }
+        }
+        ++it;
+    }
+    ALOGV("cache invalidated %lld : # of invalidated %zu",
+          (long long)mConnectionId, invalidated);
+}
+
+ResultStatus BufferPoolClient::Impl::allocateBufferHandle(
+        const std::vector<uint8_t>& params, BufferId *bufferId,
+        native_handle_t** handle) {
+    if (mLocalConnection) {
+        const native_handle_t* allocHandle = nullptr;
+        ResultStatus status = mLocalConnection->allocate(
+                params, bufferId, &allocHandle);
+        if (status == ResultStatus::OK) {
+            *handle = native_handle_clone(allocHandle);
+        }
+        ALOGV("client allocate result %lld %d : %u clone %p",
+              (long long)mConnectionId, status == ResultStatus::OK,
+              *handle ? *bufferId : 0 , *handle);
+        return status;
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus BufferPoolClient::Impl::fetchBufferHandle(
+        TransactionId transactionId, BufferId bufferId,
+        native_handle_t **handle) {
+    sp<IConnection> connection;
+    if (mLocal) {
+        connection = mLocalConnection;
+    } else {
+        connection = mRemoteConnection;
+    }
+    ResultStatus status;
+    Return<void> transResult = connection->fetch(
+            transactionId, bufferId,
+            [&status, &handle]
+            (ResultStatus outStatus, Buffer outBuffer) {
+                status = outStatus;
+                if (status == ResultStatus::OK) {
+                    *handle = native_handle_clone(
+                            outBuffer.buffer.getNativeHandle());
+                }
+            });
+    return transResult.isOk() ? status : ResultStatus::CRITICAL_ERROR;
+}
+
+
+BufferPoolClient::BufferPoolClient(const sp<Accessor> &accessor,
+                                   const sp<IObserver> &observer) {
+    mImpl = std::make_shared<Impl>(accessor, observer);
+}
+
+BufferPoolClient::BufferPoolClient(const sp<IAccessor> &accessor,
+                                   const sp<IObserver> &observer) {
+    mImpl = std::make_shared<Impl>(accessor, observer);
+}
+
+BufferPoolClient::~BufferPoolClient() {
+    // TODO: how to handle orphaned buffers?
+}
+
+bool BufferPoolClient::isValid() {
+    return mImpl && mImpl->isValid();
+}
+
+bool BufferPoolClient::isLocal() {
+    return mImpl && mImpl->isLocal();
+}
+
+bool BufferPoolClient::isActive(int64_t *lastTransactionUs, bool clearCache) {
+    if (!isValid()) {
+        *lastTransactionUs = 0;
+        return false;
+    }
+    return mImpl->isActive(lastTransactionUs, clearCache);
+}
+
+ConnectionId BufferPoolClient::getConnectionId() {
+    if (isValid()) {
+        return mImpl->getConnectionId();
+    }
+    return -1;
+}
+
+ResultStatus BufferPoolClient::getAccessor(sp<IAccessor> *accessor) {
+    if (isValid()) {
+        *accessor = mImpl->getAccessor();
+        return ResultStatus::OK;
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+void BufferPoolClient::receiveInvalidation(uint32_t msgId) {
+    ALOGV("bufferpool2 client recv inv %u", msgId);
+    if (isValid()) {
+        mImpl->receiveInvalidation(msgId);
+    }
+}
+
+ResultStatus BufferPoolClient::flush() {
+    if (isValid()) {
+        return mImpl->flush();
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus BufferPoolClient::allocate(
+        const std::vector<uint8_t> &params,
+        native_handle_t **handle,
+        std::shared_ptr<BufferPoolData> *buffer) {
+    if (isValid()) {
+        return mImpl->allocate(params, handle, buffer);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus BufferPoolClient::receive(
+        TransactionId transactionId, BufferId bufferId, int64_t timestampUs,
+        native_handle_t **handle, std::shared_ptr<BufferPoolData> *buffer) {
+    if (isValid()) {
+        return mImpl->receive(transactionId, bufferId, timestampUs, handle, buffer);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus BufferPoolClient::postSend(
+        ConnectionId receiverId,
+        const std::shared_ptr<BufferPoolData> &buffer,
+        TransactionId *transactionId,
+        int64_t *timestampUs) {
+    if (isValid()) {
+        bool result = mImpl->postSend(
+                buffer->mId, receiverId, transactionId, timestampUs);
+        return result ? ResultStatus::OK : ResultStatus::CRITICAL_ERROR;
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
diff --git a/media/bufferpool/aidl/default/BufferPoolClient.h b/media/bufferpool/aidl/default/BufferPoolClient.h
new file mode 100644
index 0000000..e8d9ae6
--- /dev/null
+++ b/media/bufferpool/aidl/default/BufferPoolClient.h
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_BUFFERPOOLCLIENT_H
+#define ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_BUFFERPOOLCLIENT_H
+
+#include <memory>
+#include <android/hardware/media/bufferpool/2.0/IAccessor.h>
+#include <android/hardware/media/bufferpool/2.0/IConnection.h>
+#include <android/hardware/media/bufferpool/2.0/IObserver.h>
+#include <bufferpool/BufferPoolTypes.h>
+#include <cutils/native_handle.h>
+#include "Accessor.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+using ::android::hardware::media::bufferpool::V2_0::IAccessor;
+using ::android::hardware::media::bufferpool::V2_0::IConnection;
+using ::android::hardware::media::bufferpool::V2_0::IObserver;
+using ::android::hardware::media::bufferpool::V2_0::ResultStatus;
+using ::android::sp;
+
+/**
+ * A buffer pool client for a buffer pool. For a specific buffer pool, at most
+ * one buffer pool client exists per process. This class will not be exposed
+ * outside. A buffer pool client will be used via ClientManager.
+ */
+class BufferPoolClient {
+public:
+    /**
+     * Creates a buffer pool client from a local buffer pool
+     * (via ClientManager#create).
+     */
+    explicit BufferPoolClient(const sp<Accessor> &accessor,
+                              const sp<IObserver> &observer);
+
+    /**
+     * Creates a buffer pool client from a remote buffer pool
+     * (via ClientManager#registerSender).
+     * Note: A buffer pool client created with remote buffer pool cannot
+     * allocate a buffer.
+     */
+    explicit BufferPoolClient(const sp<IAccessor> &accessor,
+                              const sp<IObserver> &observer);
+
+    /** Destructs a buffer pool client. */
+    ~BufferPoolClient();
+
+private:
+    bool isValid();
+
+    bool isLocal();
+
+    bool isActive(int64_t *lastTransactionUs, bool clearCache);
+
+    ConnectionId getConnectionId();
+
+    ResultStatus getAccessor(sp<IAccessor> *accessor);
+
+    void receiveInvalidation(uint32_t msgId);
+
+    ResultStatus flush();
+
+    ResultStatus allocate(const std::vector<uint8_t> &params,
+                          native_handle_t **handle,
+                          std::shared_ptr<BufferPoolData> *buffer);
+
+    ResultStatus receive(TransactionId transactionId,
+                         BufferId bufferId,
+                         int64_t timestampUs,
+                         native_handle_t **handle,
+                         std::shared_ptr<BufferPoolData> *buffer);
+
+    ResultStatus postSend(ConnectionId receiver,
+                          const std::shared_ptr<BufferPoolData> &buffer,
+                          TransactionId *transactionId,
+                          int64_t *timestampUs);
+
+    class Impl;
+    std::shared_ptr<Impl> mImpl;
+
+    friend struct ClientManager;
+    friend struct Observer;
+};
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_BUFFERPOOLCLIENT_H
diff --git a/media/bufferpool/aidl/default/BufferStatus.cpp b/media/bufferpool/aidl/default/BufferStatus.cpp
new file mode 100644
index 0000000..6937260
--- /dev/null
+++ b/media/bufferpool/aidl/default/BufferStatus.cpp
@@ -0,0 +1,304 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "BufferPoolStatus"
+//#define LOG_NDEBUG 0
+
+#include <thread>
+#include <time.h>
+#include "BufferStatus.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+int64_t getTimestampNow() {
+    int64_t stamp;
+    struct timespec ts;
+    // TODO: CLOCK_MONOTONIC_COARSE?
+    clock_gettime(CLOCK_MONOTONIC, &ts);
+    stamp = ts.tv_nsec / 1000;
+    stamp += (ts.tv_sec * 1000000LL);
+    return stamp;
+}
+
+bool isMessageLater(uint32_t curMsgId, uint32_t prevMsgId) {
+    return curMsgId != prevMsgId && curMsgId - prevMsgId < prevMsgId - curMsgId;
+}
+
+bool isBufferInRange(BufferId from, BufferId to, BufferId bufferId) {
+    if (from < to) {
+        return from <= bufferId && bufferId < to;
+    } else { // wrap happens
+        return from <= bufferId || bufferId < to;
+    }
+}
+
+static constexpr int kNumElementsInQueue = 1024*16;
+static constexpr int kMinElementsToSyncInQueue = 128;
+
+ResultStatus BufferStatusObserver::open(
+        ConnectionId id, const StatusDescriptor** fmqDescPtr) {
+    if (mBufferStatusQueues.find(id) != mBufferStatusQueues.end()) {
+        // TODO: id collision log?
+        return ResultStatus::CRITICAL_ERROR;
+    }
+    std::unique_ptr<BufferStatusQueue> queue =
+            std::make_unique<BufferStatusQueue>(kNumElementsInQueue);
+    if (!queue || queue->isValid() == false) {
+        *fmqDescPtr = nullptr;
+        return ResultStatus::NO_MEMORY;
+    } else {
+        *fmqDescPtr = queue->getDesc();
+    }
+    auto result = mBufferStatusQueues.insert(
+            std::make_pair(id, std::move(queue)));
+    if (!result.second) {
+        *fmqDescPtr = nullptr;
+        return ResultStatus::NO_MEMORY;
+    }
+    return ResultStatus::OK;
+}
+
+ResultStatus BufferStatusObserver::close(ConnectionId id) {
+    if (mBufferStatusQueues.find(id) == mBufferStatusQueues.end()) {
+        return ResultStatus::CRITICAL_ERROR;
+    }
+    mBufferStatusQueues.erase(id);
+    return ResultStatus::OK;
+}
+
+void BufferStatusObserver::getBufferStatusChanges(std::vector<BufferStatusMessage> &messages) {
+    for (auto it = mBufferStatusQueues.begin(); it != mBufferStatusQueues.end(); ++it) {
+        BufferStatusMessage message;
+        size_t avail = it->second->availableToRead();
+        while (avail > 0) {
+            if (!it->second->read(&message, 1)) {
+                // Since avaliable # of reads are already confirmed,
+                // this should not happen.
+                // TODO: error handling (spurious client?)
+                ALOGW("FMQ message cannot be read from %lld", (long long)it->first);
+                return;
+            }
+            message.connectionId = it->first;
+            messages.push_back(message);
+            --avail;
+        }
+    }
+}
+
+BufferStatusChannel::BufferStatusChannel(
+        const StatusDescriptor &fmqDesc) {
+    std::unique_ptr<BufferStatusQueue> queue =
+            std::make_unique<BufferStatusQueue>(fmqDesc);
+    if (!queue || queue->isValid() == false) {
+        mValid = false;
+        return;
+    }
+    mValid  = true;
+    mBufferStatusQueue = std::move(queue);
+}
+
+bool BufferStatusChannel::isValid() {
+    return mValid;
+}
+
+bool BufferStatusChannel::needsSync() {
+    if (mValid) {
+        size_t avail = mBufferStatusQueue->availableToWrite();
+        return avail + kMinElementsToSyncInQueue < kNumElementsInQueue;
+    }
+    return false;
+}
+
+void BufferStatusChannel::postBufferRelease(
+        ConnectionId connectionId,
+        std::list<BufferId> &pending, std::list<BufferId> &posted) {
+    if (mValid && pending.size() > 0) {
+        size_t avail = mBufferStatusQueue->availableToWrite();
+        avail = std::min(avail, pending.size());
+        BufferStatusMessage message;
+        for (size_t i = 0 ; i < avail; ++i) {
+            BufferId id = pending.front();
+            message.newStatus = BufferStatus::NOT_USED;
+            message.bufferId = id;
+            message.connectionId = connectionId;
+            if (!mBufferStatusQueue->write(&message, 1)) {
+                // Since avaliable # of writes are already confirmed,
+                // this should not happen.
+                // TODO: error handing?
+                ALOGW("FMQ message cannot be sent from %lld", (long long)connectionId);
+                return;
+            }
+            pending.pop_front();
+            posted.push_back(id);
+        }
+    }
+}
+
+void BufferStatusChannel::postBufferInvalidateAck(
+        ConnectionId connectionId,
+        uint32_t invalidateId,
+        bool *invalidated) {
+    if (mValid && !*invalidated) {
+        size_t avail = mBufferStatusQueue->availableToWrite();
+        if (avail > 0) {
+            BufferStatusMessage message;
+            message.newStatus = BufferStatus::INVALIDATION_ACK;
+            message.bufferId = invalidateId;
+            message.connectionId = connectionId;
+            if (!mBufferStatusQueue->write(&message, 1)) {
+                // Since avaliable # of writes are already confirmed,
+                // this should not happen.
+                // TODO: error handing?
+                ALOGW("FMQ message cannot be sent from %lld", (long long)connectionId);
+                return;
+            }
+            *invalidated = true;
+        }
+    }
+}
+
+bool BufferStatusChannel::postBufferStatusMessage(
+        TransactionId transactionId, BufferId bufferId,
+        BufferStatus status, ConnectionId connectionId, ConnectionId targetId,
+        std::list<BufferId> &pending, std::list<BufferId> &posted) {
+    if (mValid) {
+        size_t avail = mBufferStatusQueue->availableToWrite();
+        size_t numPending = pending.size();
+        if (avail >= numPending + 1) {
+            BufferStatusMessage release, message;
+            for (size_t i = 0; i < numPending; ++i) {
+                BufferId id = pending.front();
+                release.newStatus = BufferStatus::NOT_USED;
+                release.bufferId = id;
+                release.connectionId = connectionId;
+                if (!mBufferStatusQueue->write(&release, 1)) {
+                    // Since avaliable # of writes are already confirmed,
+                    // this should not happen.
+                    // TODO: error handling?
+                    ALOGW("FMQ message cannot be sent from %lld", (long long)connectionId);
+                    return false;
+                }
+                pending.pop_front();
+                posted.push_back(id);
+            }
+            message.transactionId = transactionId;
+            message.bufferId = bufferId;
+            message.newStatus = status;
+            message.connectionId = connectionId;
+            message.targetConnectionId = targetId;
+            // TODO : timesatamp
+            message.timestampUs = 0;
+            if (!mBufferStatusQueue->write(&message, 1)) {
+                // Since avaliable # of writes are already confirmed,
+                // this should not happen.
+                ALOGW("FMQ message cannot be sent from %lld", (long long)connectionId);
+                return false;
+            }
+            return true;
+        }
+    }
+    return false;
+}
+
+BufferInvalidationListener::BufferInvalidationListener(
+        const InvalidationDescriptor &fmqDesc) {
+    std::unique_ptr<BufferInvalidationQueue> queue =
+            std::make_unique<BufferInvalidationQueue>(fmqDesc);
+    if (!queue || queue->isValid() == false) {
+        mValid = false;
+        return;
+    }
+    mValid  = true;
+    mBufferInvalidationQueue = std::move(queue);
+    // drain previous messages
+    size_t avail = std::min(
+            mBufferInvalidationQueue->availableToRead(), (size_t) kNumElementsInQueue);
+    std::vector<BufferInvalidationMessage> temp(avail);
+    if (avail > 0) {
+        mBufferInvalidationQueue->read(temp.data(), avail);
+    }
+}
+
+void BufferInvalidationListener::getInvalidations(
+        std::vector<BufferInvalidationMessage> &messages) {
+    // Try twice in case of overflow.
+    // TODO: handling overflow though it may not happen.
+    for (int i = 0; i < 2; ++i) {
+        size_t avail = std::min(
+                mBufferInvalidationQueue->availableToRead(), (size_t) kNumElementsInQueue);
+        if (avail > 0) {
+            std::vector<BufferInvalidationMessage> temp(avail);
+            if (mBufferInvalidationQueue->read(temp.data(), avail)) {
+                messages.reserve(messages.size() + avail);
+                for (auto it = temp.begin(); it != temp.end(); ++it) {
+                    messages.push_back(*it);
+                }
+                break;
+            }
+        } else {
+            return;
+        }
+    }
+}
+
+bool BufferInvalidationListener::isValid() {
+    return mValid;
+}
+
+BufferInvalidationChannel::BufferInvalidationChannel()
+    : mValid(true),
+      mBufferInvalidationQueue(
+              std::make_unique<BufferInvalidationQueue>(kNumElementsInQueue, true)) {
+    if (!mBufferInvalidationQueue || mBufferInvalidationQueue->isValid() == false) {
+        mValid = false;
+    }
+}
+
+bool BufferInvalidationChannel::isValid() {
+    return mValid;
+}
+
+void BufferInvalidationChannel::getDesc(const InvalidationDescriptor **fmqDescPtr) {
+    if (mValid) {
+        *fmqDescPtr = mBufferInvalidationQueue->getDesc();
+    } else {
+        *fmqDescPtr = nullptr;
+    }
+}
+
+void BufferInvalidationChannel::postInvalidation(
+        uint32_t msgId, BufferId fromId, BufferId toId) {
+    BufferInvalidationMessage message;
+
+    message.messageId = msgId;
+    message.fromBufferId = fromId;
+    message.toBufferId = toId;
+    // TODO: handle failure (it does not happen normally.)
+    mBufferInvalidationQueue->write(&message);
+}
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
+
diff --git a/media/bufferpool/aidl/default/BufferStatus.h b/media/bufferpool/aidl/default/BufferStatus.h
new file mode 100644
index 0000000..fa65838
--- /dev/null
+++ b/media/bufferpool/aidl/default/BufferStatus.h
@@ -0,0 +1,230 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_BUFFERSTATUS_H
+#define ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_BUFFERSTATUS_H
+
+#include <android/hardware/media/bufferpool/2.0/types.h>
+#include <bufferpool/BufferPoolTypes.h>
+#include <fmq/MessageQueue.h>
+#include <hidl/MQDescriptor.h>
+#include <hidl/Status.h>
+#include <memory>
+#include <mutex>
+#include <vector>
+#include <list>
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+/** Returns monotonic timestamp in Us since fixed point in time. */
+int64_t getTimestampNow();
+
+bool isMessageLater(uint32_t curMsgId, uint32_t prevMsgId);
+
+bool isBufferInRange(BufferId from, BufferId to, BufferId bufferId);
+
+/**
+ * A collection of buffer status message FMQ for a buffer pool. buffer
+ * ownership/status change messages are sent via the FMQs from the clients.
+ */
+class BufferStatusObserver {
+private:
+    std::map<ConnectionId, std::unique_ptr<BufferStatusQueue>>
+            mBufferStatusQueues;
+
+public:
+    /** Creates a buffer status message FMQ for the specified
+     * connection(client).
+     *
+     * @param connectionId  connection Id of the specified client.
+     * @param fmqDescPtr    double ptr of created FMQ's descriptor.
+     *
+     * @return OK if FMQ is created successfully.
+     *         NO_MEMORY when there is no memory.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus open(ConnectionId id, const StatusDescriptor** fmqDescPtr);
+
+    /** Closes a buffer status message FMQ for the specified
+     * connection(client).
+     *
+     * @param connectionId  connection Id of the specified client.
+     *
+     * @return OK if the specified connection is closed successfully.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus close(ConnectionId id);
+
+    /** Retrieves all pending FMQ buffer status messages from clients.
+     *
+     * @param messages  retrieved pending messages.
+     */
+    void getBufferStatusChanges(std::vector<BufferStatusMessage> &messages);
+};
+
+/**
+ * A buffer status message FMQ for a buffer pool client. Buffer ownership/status
+ * change messages are sent via the fmq to the buffer pool.
+ */
+class BufferStatusChannel {
+private:
+    bool mValid;
+    std::unique_ptr<BufferStatusQueue> mBufferStatusQueue;
+
+public:
+    /**
+     * Connects to a buffer status message FMQ from a descriptor of
+     * the created FMQ.
+     *
+     * @param fmqDesc   Descriptor of the created FMQ.
+     */
+    BufferStatusChannel(const StatusDescriptor &fmqDesc);
+
+    /** Returns whether the FMQ is connected successfully. */
+    bool isValid();
+
+    /** Returns whether the FMQ needs to be synced from the buffer pool */
+    bool needsSync();
+
+    /**
+     * Posts a buffer release message to the buffer pool.
+     *
+     * @param connectionId  connection Id of the client.
+     * @param pending       currently pending buffer release messages.
+     * @param posted        posted buffer release messages.
+     */
+    void postBufferRelease(
+            ConnectionId connectionId,
+            std::list<BufferId> &pending, std::list<BufferId> &posted);
+
+    /**
+     * Posts a buffer status message regarding the specified buffer
+     * transfer transaction.
+     *
+     * @param transactionId Id of the specified transaction.
+     * @param bufferId      buffer Id of the specified transaction.
+     * @param status        new status of the buffer.
+     * @param connectionId  connection Id of the client.
+     * @param targetId      connection Id of the receiver(only when the sender
+     *                      posts a status message).
+     * @param pending       currently pending buffer release messages.
+     * @param posted        posted buffer release messages.
+     *
+     * @return {@code true} when the specified message is posted,
+     *         {@code false} otherwise.
+     */
+    bool postBufferStatusMessage(
+            TransactionId transactionId,
+            BufferId bufferId,
+            BufferStatus status,
+            ConnectionId connectionId,
+            ConnectionId targetId,
+            std::list<BufferId> &pending, std::list<BufferId> &posted);
+
+    /**
+     * Posts a buffer invaliadation messge to the buffer pool.
+     *
+     * @param connectionId  connection Id of the client.
+     * @param invalidateId  invalidation ack to the buffer pool.
+     *                      if invalidation id is zero, the ack will not be
+     *                      posted.
+     * @param invalidated   sets {@code true} only when the invalidation ack is
+     *                      posted.
+     */
+    void postBufferInvalidateAck(
+            ConnectionId connectionId,
+            uint32_t invalidateId,
+            bool *invalidated);
+};
+
+/**
+ * A buffer invalidation FMQ for a buffer pool client. Buffer invalidation
+ * messages are received via the fmq from the buffer pool. Buffer invalidation
+ * messages are handled as soon as possible.
+ */
+class BufferInvalidationListener {
+private:
+    bool mValid;
+    std::unique_ptr<BufferInvalidationQueue> mBufferInvalidationQueue;
+
+public:
+    /**
+     * Connects to a buffer invalidation FMQ from a descriptor of the created FMQ.
+     *
+     * @param fmqDesc   Descriptor of the created FMQ.
+     */
+    BufferInvalidationListener(const InvalidationDescriptor &fmqDesc);
+
+    /** Retrieves all pending buffer invalidation messages from the buffer pool.
+     *
+     * @param messages  retrieved pending messages.
+     */
+    void getInvalidations(std::vector<BufferInvalidationMessage> &messages);
+
+    /** Returns whether the FMQ is connected succesfully. */
+    bool isValid();
+};
+
+/**
+ * A buffer invalidation FMQ for a buffer pool. A buffer pool will send buffer
+ * invalidation messages to the clients via the FMQ. The FMQ is shared among
+ * buffer pool clients.
+ */
+class BufferInvalidationChannel {
+private:
+    bool mValid;
+    std::unique_ptr<BufferInvalidationQueue> mBufferInvalidationQueue;
+
+public:
+    /**
+     * Creates a buffer invalidation FMQ for a buffer pool.
+     */
+    BufferInvalidationChannel();
+
+    /** Returns whether the FMQ is connected succesfully. */
+    bool isValid();
+
+    /**
+     * Retrieves the descriptor of a buffer invalidation FMQ. the descriptor may
+     * be passed to the client for buffer invalidation handling.
+     *
+     * @param fmqDescPtr    double ptr of created FMQ's descriptor.
+     */
+    void getDesc(const InvalidationDescriptor **fmqDescPtr);
+
+    /** Posts a buffer invalidation for invalidated buffers.
+     *
+     * @param msgId     Invalidation message id which is used when clients send
+     *                  acks back via BufferStatusMessage
+     * @param fromId    The start bufferid of the invalidated buffers(inclusive)
+     * @param toId      The end bufferId of the invalidated buffers(inclusive)
+     */
+    void postInvalidation(uint32_t msgId, BufferId fromId, BufferId toId);
+};
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_BUFFERSTATUS_H
diff --git a/media/bufferpool/aidl/default/ClientManager.cpp b/media/bufferpool/aidl/default/ClientManager.cpp
new file mode 100644
index 0000000..54a20b9
--- /dev/null
+++ b/media/bufferpool/aidl/default/ClientManager.cpp
@@ -0,0 +1,569 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#define LOG_TAG "BufferPoolManager"
+//#define LOG_NDEBUG 0
+
+#include <bufferpool/ClientManager.h>
+#include <hidl/HidlTransportSupport.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+#include <utils/Log.h>
+#include "BufferPoolClient.h"
+#include "Observer.h"
+#include "Accessor.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+static constexpr int64_t kRegisterTimeoutUs = 500000; // 0.5 sec
+static constexpr int64_t kCleanUpDurationUs = 1000000; // TODO: 1 sec tune
+static constexpr int64_t kClientTimeoutUs = 5000000; // TODO: 5 secs tune
+
+/**
+ * The holder of the cookie of remote IClientManager.
+ * The cookie is process locally unique for each IClientManager.
+ * (The cookie is used to notify death of clients to bufferpool process.)
+ */
+class ClientManagerCookieHolder {
+public:
+    /**
+     * Creates a cookie holder for remote IClientManager(s).
+     */
+    ClientManagerCookieHolder();
+
+    /**
+     * Gets a cookie for a remote IClientManager.
+     *
+     * @param manager   the specified remote IClientManager.
+     * @param added     true when the specified remote IClientManager is added
+     *                  newly, false otherwise.
+     *
+     * @return the process locally unique cookie for the specified IClientManager.
+     */
+    uint64_t getCookie(const sp<IClientManager> &manager, bool *added);
+
+private:
+    uint64_t mSeqId;
+    std::mutex mLock;
+    std::list<std::pair<const wp<IClientManager>, uint64_t>> mManagers;
+};
+
+ClientManagerCookieHolder::ClientManagerCookieHolder() : mSeqId(0){}
+
+uint64_t ClientManagerCookieHolder::getCookie(
+        const sp<IClientManager> &manager,
+        bool *added) {
+    std::lock_guard<std::mutex> lock(mLock);
+    for (auto it = mManagers.begin(); it != mManagers.end();) {
+        const sp<IClientManager> key = it->first.promote();
+        if (key) {
+            if (interfacesEqual(key, manager)) {
+                *added = false;
+                return it->second;
+            }
+            ++it;
+        } else {
+            it = mManagers.erase(it);
+        }
+    }
+    uint64_t id = mSeqId++;
+    *added = true;
+    mManagers.push_back(std::make_pair(manager, id));
+    return id;
+}
+
+class ClientManager::Impl {
+public:
+    Impl();
+
+    // BnRegisterSender
+    ResultStatus registerSender(const sp<IAccessor> &accessor,
+                                ConnectionId *pConnectionId);
+
+    // BpRegisterSender
+    ResultStatus registerSender(const sp<IClientManager> &receiver,
+                                ConnectionId senderId,
+                                ConnectionId *receiverId);
+
+    ResultStatus create(const std::shared_ptr<BufferPoolAllocator> &allocator,
+                        ConnectionId *pConnectionId);
+
+    ResultStatus close(ConnectionId connectionId);
+
+    ResultStatus flush(ConnectionId connectionId);
+
+    ResultStatus allocate(ConnectionId connectionId,
+                          const std::vector<uint8_t> &params,
+                          native_handle_t **handle,
+                          std::shared_ptr<BufferPoolData> *buffer);
+
+    ResultStatus receive(ConnectionId connectionId,
+                         TransactionId transactionId,
+                         BufferId bufferId,
+                         int64_t timestampUs,
+                         native_handle_t **handle,
+                         std::shared_ptr<BufferPoolData> *buffer);
+
+    ResultStatus postSend(ConnectionId receiverId,
+                          const std::shared_ptr<BufferPoolData> &buffer,
+                          TransactionId *transactionId,
+                          int64_t *timestampUs);
+
+    ResultStatus getAccessor(ConnectionId connectionId,
+                             sp<IAccessor> *accessor);
+
+    void cleanUp(bool clearCache = false);
+
+private:
+    // In order to prevent deadlock between multiple locks,
+    // always lock ClientCache.lock before locking ActiveClients.lock.
+    struct ClientCache {
+        // This lock is held for brief duration.
+        // Blocking operation is not performed while holding the lock.
+        std::mutex mMutex;
+        std::list<std::pair<const wp<IAccessor>, const std::weak_ptr<BufferPoolClient>>>
+                mClients;
+        std::condition_variable mConnectCv;
+        bool mConnecting;
+        int64_t mLastCleanUpUs;
+
+        ClientCache() : mConnecting(false), mLastCleanUpUs(getTimestampNow()) {}
+    } mCache;
+
+    // Active clients which can be retrieved via ConnectionId
+    struct ActiveClients {
+        // This lock is held for brief duration.
+        // Blocking operation is not performed holding the lock.
+        std::mutex mMutex;
+        std::map<ConnectionId, const std::shared_ptr<BufferPoolClient>>
+                mClients;
+    } mActive;
+
+    sp<Observer> mObserver;
+
+    ClientManagerCookieHolder mRemoteClientCookies;
+};
+
+ClientManager::Impl::Impl()
+    : mObserver(new Observer()) {}
+
+ResultStatus ClientManager::Impl::registerSender(
+        const sp<IAccessor> &accessor, ConnectionId *pConnectionId) {
+    cleanUp();
+    int64_t timeoutUs = getTimestampNow() + kRegisterTimeoutUs;
+    do {
+        std::unique_lock<std::mutex> lock(mCache.mMutex);
+        for (auto it = mCache.mClients.begin(); it != mCache.mClients.end(); ++it) {
+            sp<IAccessor> sAccessor = it->first.promote();
+            if (sAccessor && interfacesEqual(sAccessor, accessor)) {
+                const std::shared_ptr<BufferPoolClient> client = it->second.lock();
+                if (client) {
+                    std::lock_guard<std::mutex> lock(mActive.mMutex);
+                    *pConnectionId = client->getConnectionId();
+                    if (mActive.mClients.find(*pConnectionId) != mActive.mClients.end()) {
+                        ALOGV("register existing connection %lld", (long long)*pConnectionId);
+                        return ResultStatus::ALREADY_EXISTS;
+                    }
+                }
+                mCache.mClients.erase(it);
+                break;
+            }
+        }
+        if (!mCache.mConnecting) {
+            mCache.mConnecting = true;
+            lock.unlock();
+            ResultStatus result = ResultStatus::OK;
+            const std::shared_ptr<BufferPoolClient> client =
+                    std::make_shared<BufferPoolClient>(accessor, mObserver);
+            lock.lock();
+            if (!client) {
+                result = ResultStatus::NO_MEMORY;
+            } else if (!client->isValid()) {
+                result = ResultStatus::CRITICAL_ERROR;
+            }
+            if (result == ResultStatus::OK) {
+                // TODO: handle insert fail. (malloc fail)
+                const std::weak_ptr<BufferPoolClient> wclient = client;
+                mCache.mClients.push_back(std::make_pair(accessor, wclient));
+                ConnectionId conId = client->getConnectionId();
+                mObserver->addClient(conId, wclient);
+                {
+                    std::lock_guard<std::mutex> lock(mActive.mMutex);
+                    mActive.mClients.insert(std::make_pair(conId, client));
+                }
+                *pConnectionId = conId;
+                ALOGV("register new connection %lld", (long long)*pConnectionId);
+            }
+            mCache.mConnecting = false;
+            lock.unlock();
+            mCache.mConnectCv.notify_all();
+            return result;
+        }
+        mCache.mConnectCv.wait_for(
+                lock, std::chrono::microseconds(kRegisterTimeoutUs));
+    } while (getTimestampNow() < timeoutUs);
+    // TODO: return timeout error
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus ClientManager::Impl::registerSender(
+        const sp<IClientManager> &receiver,
+        ConnectionId senderId,
+        ConnectionId *receiverId) {
+    sp<IAccessor> accessor;
+    bool local = false;
+    {
+        std::lock_guard<std::mutex> lock(mActive.mMutex);
+        auto it = mActive.mClients.find(senderId);
+        if (it == mActive.mClients.end()) {
+            return ResultStatus::NOT_FOUND;
+        }
+        it->second->getAccessor(&accessor);
+        local = it->second->isLocal();
+    }
+    ResultStatus rs = ResultStatus::CRITICAL_ERROR;
+    if (accessor) {
+       Return<void> transResult = receiver->registerSender(
+                accessor,
+                [&rs, receiverId](
+                        ResultStatus status,
+                        int64_t connectionId) {
+                    rs = status;
+                    *receiverId = connectionId;
+                });
+        if (!transResult.isOk()) {
+            return ResultStatus::CRITICAL_ERROR;
+        } else if (local && rs == ResultStatus::OK) {
+            sp<ConnectionDeathRecipient> recipient = Accessor::getConnectionDeathRecipient();
+            if (recipient)  {
+                ALOGV("client death recipient registered %lld", (long long)*receiverId);
+                bool added;
+                uint64_t cookie = mRemoteClientCookies.getCookie(receiver, &added);
+                recipient->addCookieToConnection(cookie, *receiverId);
+                if (added) {
+                    Return<bool> transResult = receiver->linkToDeath(recipient, cookie);
+                }
+            }
+        }
+    }
+    return rs;
+}
+
+ResultStatus ClientManager::Impl::create(
+        const std::shared_ptr<BufferPoolAllocator> &allocator,
+        ConnectionId *pConnectionId) {
+    const sp<Accessor> accessor = new Accessor(allocator);
+    if (!accessor || !accessor->isValid()) {
+        return ResultStatus::CRITICAL_ERROR;
+    }
+    // TODO: observer is local. use direct call instead of hidl call.
+    std::shared_ptr<BufferPoolClient> client =
+            std::make_shared<BufferPoolClient>(accessor, mObserver);
+    if (!client || !client->isValid()) {
+        return ResultStatus::CRITICAL_ERROR;
+    }
+    // Since a new bufferpool is created, evict memories which are used by
+    // existing bufferpools and clients.
+    cleanUp(true);
+    {
+        // TODO: handle insert fail. (malloc fail)
+        std::lock_guard<std::mutex> lock(mCache.mMutex);
+        const std::weak_ptr<BufferPoolClient> wclient = client;
+        mCache.mClients.push_back(std::make_pair(accessor, wclient));
+        ConnectionId conId = client->getConnectionId();
+        mObserver->addClient(conId, wclient);
+        {
+            std::lock_guard<std::mutex> lock(mActive.mMutex);
+            mActive.mClients.insert(std::make_pair(conId, client));
+        }
+        *pConnectionId = conId;
+        ALOGV("create new connection %lld", (long long)*pConnectionId);
+    }
+    return ResultStatus::OK;
+}
+
+ResultStatus ClientManager::Impl::close(ConnectionId connectionId) {
+    std::unique_lock<std::mutex> lock1(mCache.mMutex);
+    std::unique_lock<std::mutex> lock2(mActive.mMutex);
+    auto it = mActive.mClients.find(connectionId);
+    if (it != mActive.mClients.end()) {
+        sp<IAccessor> accessor;
+        it->second->getAccessor(&accessor);
+        std::shared_ptr<BufferPoolClient> closing = it->second;
+        mActive.mClients.erase(connectionId);
+        for (auto cit = mCache.mClients.begin(); cit != mCache.mClients.end();) {
+            // clean up dead client caches
+            sp<IAccessor> cAccessor = cit->first.promote();
+            if (!cAccessor || (accessor && interfacesEqual(cAccessor, accessor))) {
+                cit = mCache.mClients.erase(cit);
+            } else {
+                cit++;
+            }
+        }
+        lock2.unlock();
+        lock1.unlock();
+        closing->flush();
+        return ResultStatus::OK;
+    }
+    return ResultStatus::NOT_FOUND;
+}
+
+ResultStatus ClientManager::Impl::flush(ConnectionId connectionId) {
+    std::shared_ptr<BufferPoolClient> client;
+    {
+        std::lock_guard<std::mutex> lock(mActive.mMutex);
+        auto it = mActive.mClients.find(connectionId);
+        if (it == mActive.mClients.end()) {
+            return ResultStatus::NOT_FOUND;
+        }
+        client = it->second;
+    }
+    return client->flush();
+}
+
+ResultStatus ClientManager::Impl::allocate(
+        ConnectionId connectionId, const std::vector<uint8_t> &params,
+        native_handle_t **handle, std::shared_ptr<BufferPoolData> *buffer) {
+    std::shared_ptr<BufferPoolClient> client;
+    {
+        std::lock_guard<std::mutex> lock(mActive.mMutex);
+        auto it = mActive.mClients.find(connectionId);
+        if (it == mActive.mClients.end()) {
+            return ResultStatus::NOT_FOUND;
+        }
+        client = it->second;
+    }
+#ifdef BUFFERPOOL_CLONE_HANDLES
+    native_handle_t *origHandle;
+    ResultStatus res = client->allocate(params, &origHandle, buffer);
+    if (res != ResultStatus::OK) {
+        return res;
+    }
+    *handle = native_handle_clone(origHandle);
+    if (handle == NULL) {
+        buffer->reset();
+        return ResultStatus::NO_MEMORY;
+    }
+    return ResultStatus::OK;
+#else
+    return client->allocate(params, handle, buffer);
+#endif
+}
+
+ResultStatus ClientManager::Impl::receive(
+        ConnectionId connectionId, TransactionId transactionId,
+        BufferId bufferId, int64_t timestampUs,
+        native_handle_t **handle, std::shared_ptr<BufferPoolData> *buffer) {
+    std::shared_ptr<BufferPoolClient> client;
+    {
+        std::lock_guard<std::mutex> lock(mActive.mMutex);
+        auto it = mActive.mClients.find(connectionId);
+        if (it == mActive.mClients.end()) {
+            return ResultStatus::NOT_FOUND;
+        }
+        client = it->second;
+    }
+#ifdef BUFFERPOOL_CLONE_HANDLES
+    native_handle_t *origHandle;
+    ResultStatus res = client->receive(
+            transactionId, bufferId, timestampUs, &origHandle, buffer);
+    if (res != ResultStatus::OK) {
+        return res;
+    }
+    *handle = native_handle_clone(origHandle);
+    if (handle == NULL) {
+        buffer->reset();
+        return ResultStatus::NO_MEMORY;
+    }
+    return ResultStatus::OK;
+#else
+    return client->receive(transactionId, bufferId, timestampUs, handle, buffer);
+#endif
+}
+
+ResultStatus ClientManager::Impl::postSend(
+        ConnectionId receiverId, const std::shared_ptr<BufferPoolData> &buffer,
+        TransactionId *transactionId, int64_t *timestampUs) {
+    ConnectionId connectionId = buffer->mConnectionId;
+    std::shared_ptr<BufferPoolClient> client;
+    {
+        std::lock_guard<std::mutex> lock(mActive.mMutex);
+        auto it = mActive.mClients.find(connectionId);
+        if (it == mActive.mClients.end()) {
+            return ResultStatus::NOT_FOUND;
+        }
+        client = it->second;
+    }
+    return client->postSend(receiverId, buffer, transactionId, timestampUs);
+}
+
+ResultStatus ClientManager::Impl::getAccessor(
+        ConnectionId connectionId, sp<IAccessor> *accessor) {
+    std::shared_ptr<BufferPoolClient> client;
+    {
+        std::lock_guard<std::mutex> lock(mActive.mMutex);
+        auto it = mActive.mClients.find(connectionId);
+        if (it == mActive.mClients.end()) {
+            return ResultStatus::NOT_FOUND;
+        }
+        client = it->second;
+    }
+    return client->getAccessor(accessor);
+}
+
+void ClientManager::Impl::cleanUp(bool clearCache) {
+    int64_t now = getTimestampNow();
+    int64_t lastTransactionUs;
+    std::lock_guard<std::mutex> lock1(mCache.mMutex);
+    if (clearCache || mCache.mLastCleanUpUs + kCleanUpDurationUs < now) {
+        std::lock_guard<std::mutex> lock2(mActive.mMutex);
+        int cleaned = 0;
+        for (auto it = mActive.mClients.begin(); it != mActive.mClients.end();) {
+            if (!it->second->isActive(&lastTransactionUs, clearCache)) {
+                if (lastTransactionUs + kClientTimeoutUs < now) {
+                    sp<IAccessor> accessor;
+                    it->second->getAccessor(&accessor);
+                    it = mActive.mClients.erase(it);
+                    ++cleaned;
+                    continue;
+                }
+            }
+            ++it;
+        }
+        for (auto cit = mCache.mClients.begin(); cit != mCache.mClients.end();) {
+            // clean up dead client caches
+            sp<IAccessor> cAccessor = cit->first.promote();
+            if (!cAccessor) {
+                cit = mCache.mClients.erase(cit);
+            } else {
+                ++cit;
+            }
+        }
+        ALOGV("# of cleaned connections: %d", cleaned);
+        mCache.mLastCleanUpUs = now;
+    }
+}
+
+// Methods from ::android::hardware::media::bufferpool::V2_0::IClientManager follow.
+Return<void> ClientManager::registerSender(const sp<::android::hardware::media::bufferpool::V2_0::IAccessor>& bufferPool, registerSender_cb _hidl_cb) {
+    if (mImpl) {
+        ConnectionId connectionId = -1;
+        ResultStatus status = mImpl->registerSender(bufferPool, &connectionId);
+        _hidl_cb(status, connectionId);
+    } else {
+        _hidl_cb(ResultStatus::CRITICAL_ERROR, -1);
+    }
+    return Void();
+}
+
+// Methods for local use.
+sp<ClientManager> ClientManager::sInstance;
+std::mutex ClientManager::sInstanceLock;
+
+sp<ClientManager> ClientManager::getInstance() {
+    std::lock_guard<std::mutex> lock(sInstanceLock);
+    if (!sInstance) {
+        sInstance = new ClientManager();
+    }
+    Accessor::createInvalidator();
+    Accessor::createEvictor();
+    return sInstance;
+}
+
+ClientManager::ClientManager() : mImpl(new Impl()) {}
+
+ClientManager::~ClientManager() {
+}
+
+ResultStatus ClientManager::create(
+        const std::shared_ptr<BufferPoolAllocator> &allocator,
+        ConnectionId *pConnectionId) {
+    if (mImpl) {
+        return mImpl->create(allocator, pConnectionId);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus ClientManager::registerSender(
+        const sp<IClientManager> &receiver,
+        ConnectionId senderId,
+        ConnectionId *receiverId) {
+    if (mImpl) {
+        return mImpl->registerSender(receiver, senderId, receiverId);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus ClientManager::close(ConnectionId connectionId) {
+    if (mImpl) {
+        return mImpl->close(connectionId);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus ClientManager::flush(ConnectionId connectionId) {
+    if (mImpl) {
+        return mImpl->flush(connectionId);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus ClientManager::allocate(
+        ConnectionId connectionId, const std::vector<uint8_t> &params,
+        native_handle_t **handle, std::shared_ptr<BufferPoolData> *buffer) {
+    if (mImpl) {
+        return mImpl->allocate(connectionId, params, handle, buffer);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus ClientManager::receive(
+        ConnectionId connectionId, TransactionId transactionId,
+        BufferId bufferId, int64_t timestampUs,
+        native_handle_t **handle, std::shared_ptr<BufferPoolData> *buffer) {
+    if (mImpl) {
+        return mImpl->receive(connectionId, transactionId, bufferId,
+                              timestampUs, handle, buffer);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus ClientManager::postSend(
+        ConnectionId receiverId, const std::shared_ptr<BufferPoolData> &buffer,
+        TransactionId *transactionId, int64_t* timestampUs) {
+    if (mImpl && buffer) {
+        return mImpl->postSend(receiverId, buffer, transactionId, timestampUs);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+void ClientManager::cleanUp() {
+    if (mImpl) {
+        mImpl->cleanUp(true);
+    }
+}
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
diff --git a/media/bufferpool/aidl/default/Connection.cpp b/media/bufferpool/aidl/default/Connection.cpp
new file mode 100644
index 0000000..57d0c7e
--- /dev/null
+++ b/media/bufferpool/aidl/default/Connection.cpp
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Connection.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+// Methods from ::android::hardware::media::bufferpool::V2_0::IConnection follow.
+Return<void> Connection::fetch(uint64_t transactionId, uint32_t bufferId, fetch_cb _hidl_cb) {
+    ResultStatus status = ResultStatus::CRITICAL_ERROR;
+    if (mInitialized && mAccessor) {
+        if (bufferId != SYNC_BUFFERID) {
+            const native_handle_t *handle = nullptr;
+            status = mAccessor->fetch(
+                    mConnectionId, transactionId, bufferId, &handle);
+            if (status == ResultStatus::OK) {
+                Buffer buffer = {};
+                buffer.id = bufferId;
+                buffer.buffer = handle;
+                _hidl_cb(status, buffer);
+                return Void();
+            }
+        } else {
+            mAccessor->cleanUp(false);
+        }
+    }
+
+    Buffer buffer = {};
+    buffer.id = 0;
+    buffer.buffer = nullptr;
+
+    _hidl_cb(status, buffer);
+    return Void();
+}
+
+Connection::Connection() : mInitialized(false), mConnectionId(-1LL) {}
+
+Connection::~Connection() {
+    if (mInitialized && mAccessor) {
+        mAccessor->close(mConnectionId);
+    }
+}
+
+void Connection::initialize(
+        const sp<Accessor>& accessor, ConnectionId connectionId) {
+    if (!mInitialized) {
+        mAccessor = accessor;
+        mConnectionId = connectionId;
+        mInitialized = true;
+    }
+}
+
+ResultStatus Connection::flush() {
+    if (mInitialized && mAccessor) {
+        return mAccessor->flush();
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+ResultStatus Connection::allocate(
+        const std::vector<uint8_t> &params, BufferId *bufferId,
+        const native_handle_t **handle) {
+    if (mInitialized && mAccessor) {
+        return mAccessor->allocate(mConnectionId, params, bufferId, handle);
+    }
+    return ResultStatus::CRITICAL_ERROR;
+}
+
+void Connection::cleanUp(bool clearCache) {
+    if (mInitialized && mAccessor) {
+        mAccessor->cleanUp(clearCache);
+    }
+}
+
+// Methods from ::android::hidl::base::V1_0::IBase follow.
+
+//IConnection* HIDL_FETCH_IConnection(const char* /* name */) {
+//    return new Connection();
+//}
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
diff --git a/media/bufferpool/aidl/default/Connection.h b/media/bufferpool/aidl/default/Connection.h
new file mode 100644
index 0000000..8507749
--- /dev/null
+++ b/media/bufferpool/aidl/default/Connection.h
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_CONNECTION_H
+#define ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_CONNECTION_H
+
+#include <android/hardware/media/bufferpool/2.0/IConnection.h>
+#include <bufferpool/BufferPoolTypes.h>
+#include <hidl/MQDescriptor.h>
+#include <hidl/Status.h>
+#include "Accessor.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+using ::android::hardware::hidl_array;
+using ::android::hardware::hidl_memory;
+using ::android::hardware::hidl_string;
+using ::android::hardware::hidl_vec;
+using ::android::hardware::media::bufferpool::V2_0::implementation::Accessor;
+using ::android::hardware::Return;
+using ::android::hardware::Void;
+using ::android::sp;
+
+struct Connection : public IConnection {
+    // Methods from ::android::hardware::media::bufferpool::V2_0::IConnection follow.
+    Return<void> fetch(uint64_t transactionId, uint32_t bufferId, fetch_cb _hidl_cb) override;
+
+    /**
+     * Invalidates all buffers which are active and/or are ready to be recycled.
+     */
+    ResultStatus flush();
+
+    /**
+     * Allocates a buffer using the specified parameters. Recycles a buffer if
+     * it is possible. The returned buffer can be transferred to other remote
+     * clients(Connection).
+     *
+     * @param params    allocation parameters.
+     * @param bufferId  Id of the allocated buffer.
+     * @param handle    native handle of the allocated buffer.
+     *
+     * @return OK if a buffer is successfully allocated.
+     *         NO_MEMORY when there is no memory.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus allocate(const std::vector<uint8_t> &params,
+                          BufferId *bufferId, const native_handle_t **handle);
+
+    /**
+     * Processes pending buffer status messages and performs periodic cache cleaning
+     * from bufferpool.
+     *
+     * @param clearCache    if clearCache is true, bufferpool frees all buffers
+     *                      waiting to be recycled.
+     */
+    void cleanUp(bool clearCache);
+
+    /** Destructs a connection. */
+    ~Connection();
+
+    /** Creates a connection. */
+    Connection();
+
+    /**
+     * Initializes with the specified buffer pool and the connection id.
+     * The connection id should be unique in the whole system.
+     *
+     * @param accessor      the specified buffer pool.
+     * @param connectionId  Id.
+     */
+    void initialize(const sp<Accessor> &accessor, ConnectionId connectionId);
+
+    enum : uint32_t {
+        SYNC_BUFFERID = UINT32_MAX,
+    };
+
+private:
+    bool mInitialized;
+    sp<Accessor> mAccessor;
+    ConnectionId mConnectionId;
+};
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_CONNECTION_H
diff --git a/media/bufferpool/aidl/default/Observer.cpp b/media/bufferpool/aidl/default/Observer.cpp
new file mode 100644
index 0000000..5b23160
--- /dev/null
+++ b/media/bufferpool/aidl/default/Observer.cpp
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Observer.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+Observer::Observer() {
+}
+
+Observer::~Observer() {
+}
+
+// Methods from ::android::hardware::media::bufferpool::V2_0::IObserver follow.
+Return<void> Observer::onMessage(int64_t connectionId, uint32_t msgId) {
+    std::unique_lock<std::mutex> lock(mLock);
+    auto it = mClients.find(connectionId);
+    if (it != mClients.end()) {
+        const std::shared_ptr<BufferPoolClient> client = it->second.lock();
+        if (!client) {
+            mClients.erase(it);
+        } else {
+            lock.unlock();
+            client->receiveInvalidation(msgId);
+        }
+    }
+    return Void();
+}
+
+void Observer::addClient(ConnectionId connectionId,
+                         const std::weak_ptr<BufferPoolClient> &wclient) {
+    std::lock_guard<std::mutex> lock(mLock);
+    for (auto it = mClients.begin(); it != mClients.end();) {
+        if (!it->second.lock() || it->first == connectionId) {
+            it = mClients.erase(it);
+        } else {
+            ++it;
+        }
+    }
+    mClients.insert(std::make_pair(connectionId, wclient));
+
+}
+
+void Observer::delClient(ConnectionId connectionId) {
+    std::lock_guard<std::mutex> lock(mLock);
+    mClients.erase(connectionId);
+}
+
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
diff --git a/media/bufferpool/aidl/default/Observer.h b/media/bufferpool/aidl/default/Observer.h
new file mode 100644
index 0000000..42bd7c1
--- /dev/null
+++ b/media/bufferpool/aidl/default/Observer.h
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_OBSERVER_H
+#define ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_OBSERVER_H
+
+#include <android/hardware/media/bufferpool/2.0/IObserver.h>
+#include <hidl/MQDescriptor.h>
+#include <hidl/Status.h>
+#include "BufferPoolClient.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+using ::android::hardware::hidl_array;
+using ::android::hardware::hidl_memory;
+using ::android::hardware::hidl_string;
+using ::android::hardware::hidl_vec;
+using ::android::hardware::Return;
+using ::android::hardware::Void;
+using ::android::sp;
+
+struct Observer : public IObserver {
+    // Methods from ::android::hardware::media::bufferpool::V2_0::IObserver follow.
+    Return<void> onMessage(int64_t connectionId, uint32_t msgId) override;
+
+    ~Observer();
+
+    void addClient(ConnectionId connectionId,
+                   const std::weak_ptr<BufferPoolClient> &wclient);
+
+    void delClient(ConnectionId connectionId);
+
+private:
+    Observer();
+
+    friend struct ClientManager;
+
+    std::mutex mLock;
+    std::map<ConnectionId, const std::weak_ptr<BufferPoolClient>> mClients;
+};
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_OBSERVER_H
diff --git a/media/bufferpool/aidl/default/include/bufferpool/BufferPoolTypes.h b/media/bufferpool/aidl/default/include/bufferpool/BufferPoolTypes.h
new file mode 100644
index 0000000..7c906cb
--- /dev/null
+++ b/media/bufferpool/aidl/default/include/bufferpool/BufferPoolTypes.h
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_BUFFERPOOLTYPES_H
+#define ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_BUFFERPOOLTYPES_H
+
+#include <android/hardware/media/bufferpool/2.0/types.h>
+#include <cutils/native_handle.h>
+#include <fmq/MessageQueue.h>
+#include <hidl/MQDescriptor.h>
+#include <hidl/Status.h>
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+
+struct BufferPoolData {
+    // For local use, to specify a bufferpool (client connection) for buffers.
+    // Return value from connect#IAccessor(android.hardware.media.bufferpool@2.0).
+    int64_t mConnectionId;
+    // BufferId
+    uint32_t mId;
+
+    BufferPoolData() : mConnectionId(0), mId(0) {}
+
+    BufferPoolData(
+            int64_t connectionId, uint32_t id)
+            : mConnectionId(connectionId), mId(id) {}
+
+    ~BufferPoolData() {}
+};
+
+namespace V2_0 {
+namespace implementation {
+
+using ::android::hardware::kSynchronizedReadWrite;
+using ::android::hardware::kUnsynchronizedWrite;
+
+typedef uint32_t BufferId;
+typedef uint64_t TransactionId;
+typedef int64_t ConnectionId;
+
+enum : ConnectionId {
+    INVALID_CONNECTIONID = 0,
+};
+
+typedef android::hardware::MessageQueue<BufferStatusMessage, kSynchronizedReadWrite> BufferStatusQueue;
+typedef BufferStatusQueue::Descriptor StatusDescriptor;
+
+typedef android::hardware::MessageQueue<BufferInvalidationMessage, kUnsynchronizedWrite>
+        BufferInvalidationQueue;
+typedef BufferInvalidationQueue::Descriptor InvalidationDescriptor;
+
+/**
+ * Allocation wrapper class for buffer pool.
+ */
+struct BufferPoolAllocation {
+    const native_handle_t *mHandle;
+
+    const native_handle_t *handle() {
+        return mHandle;
+    }
+
+    BufferPoolAllocation(const native_handle_t *handle) : mHandle(handle) {}
+
+    ~BufferPoolAllocation() {};
+};
+
+/**
+ * Allocator wrapper class for buffer pool.
+ */
+class BufferPoolAllocator {
+public:
+
+    /**
+     * Allocate an allocation(buffer) for buffer pool.
+     *
+     * @param params    allocation parameters
+     * @param alloc     created allocation
+     * @param allocSize size of created allocation
+     *
+     * @return OK when an allocation is created successfully.
+     */
+    virtual ResultStatus allocate(
+            const std::vector<uint8_t> &params,
+            std::shared_ptr<BufferPoolAllocation> *alloc,
+            size_t *allocSize) = 0;
+
+    /**
+     * Returns whether allocation parameters of an old allocation are
+     * compatible with new allocation parameters.
+     */
+    virtual bool compatible(const std::vector<uint8_t> &newParams,
+                            const std::vector<uint8_t> &oldParams) = 0;
+
+protected:
+    BufferPoolAllocator() = default;
+
+    virtual ~BufferPoolAllocator() = default;
+};
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_BUFFERPOOLTYPES_H
diff --git a/media/bufferpool/aidl/default/include/bufferpool/ClientManager.h b/media/bufferpool/aidl/default/include/bufferpool/ClientManager.h
new file mode 100644
index 0000000..24b61f4
--- /dev/null
+++ b/media/bufferpool/aidl/default/include/bufferpool/ClientManager.h
@@ -0,0 +1,195 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_CLIENTMANAGER_H
+#define ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_CLIENTMANAGER_H
+
+#include <android/hardware/media/bufferpool/2.0/IClientManager.h>
+#include <hidl/MQDescriptor.h>
+#include <hidl/Status.h>
+#include <memory>
+#include "BufferPoolTypes.h"
+
+namespace android {
+namespace hardware {
+namespace media {
+namespace bufferpool {
+namespace V2_0 {
+namespace implementation {
+
+using ::android::hardware::hidl_array;
+using ::android::hardware::hidl_memory;
+using ::android::hardware::hidl_string;
+using ::android::hardware::hidl_vec;
+using ::android::hardware::media::bufferpool::V2_0::IAccessor;
+using ::android::hardware::media::bufferpool::V2_0::ResultStatus;
+using ::android::hardware::Return;
+using ::android::hardware::Void;
+using ::android::sp;
+
+struct ClientManager : public IClientManager {
+    // Methods from ::android::hardware::media::bufferpool::V2_0::IClientManager follow.
+    Return<void> registerSender(const sp<::android::hardware::media::bufferpool::V2_0::IAccessor>& bufferPool, registerSender_cb _hidl_cb) override;
+
+    /** Gets an instance. */
+    static sp<ClientManager> getInstance();
+
+    /**
+     * Creates a local connection with a newly created buffer pool.
+     *
+     * @param allocator     for new buffer allocation.
+     * @param pConnectionId Id of the created connection. This is
+     *                      system-wide unique.
+     *
+     * @return OK when a buffer pool and a local connection is successfully
+     *         created.
+     *         NO_MEMORY when there is no memory.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus create(const std::shared_ptr<BufferPoolAllocator> &allocator,
+                        ConnectionId *pConnectionId);
+
+    /**
+     * Register a created connection as sender for remote process.
+     *
+     * @param receiver      The remote receiving process.
+     * @param senderId      A local connection which will send buffers to.
+     * @param receiverId    Id of the created receiving connection on the receiver
+     *                      process.
+     *
+     * @return OK when the receiving connection is successfully created on the
+     *         receiver process.
+     *         NOT_FOUND when the sender connection was not found.
+     *         ALREADY_EXISTS the receiving connection is already made.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus registerSender(const sp<IClientManager> &receiver,
+                                ConnectionId senderId,
+                                ConnectionId *receiverId);
+
+    /**
+     * Closes the specified connection.
+     *
+     * @param connectionId  The id of the connection.
+     *
+     * @return OK when the connection is closed.
+     *         NOT_FOUND when the specified connection was not found.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus close(ConnectionId connectionId);
+
+    /**
+     * Evicts cached allocations. If it's local connection, release the
+     * previous allocations and do not recycle current active allocations.
+     *
+     * @param connectionId The id of the connection.
+     *
+     * @return OK when the connection is resetted.
+     *         NOT_FOUND when the specified connection was not found.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus flush(ConnectionId connectionId);
+
+    /**
+     * Allocates a buffer from the specified connection. The output parameter
+     * handle is cloned from the internal handle. So it is safe to use directly,
+     * and it should be deleted and destroyed after use.
+     *
+     * @param connectionId  The id of the connection.
+     * @param params        The allocation parameters.
+     * @param handle        The native handle to the allocated buffer. handle
+     *                      should be cloned before use.
+     * @param buffer        The allocated buffer.
+     *
+     * @return OK when a buffer was allocated successfully.
+     *         NOT_FOUND when the specified connection was not found.
+     *         NO_MEMORY when there is no memory.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus allocate(ConnectionId connectionId,
+                          const std::vector<uint8_t> &params,
+                          native_handle_t **handle,
+                          std::shared_ptr<BufferPoolData> *buffer);
+
+    /**
+     * Receives a buffer for the transaction. The output parameter handle is
+     * cloned from the internal handle. So it is safe to use directly, and it
+     * should be deleted and destoyed after use.
+     *
+     * @param connectionId  The id of the receiving connection.
+     * @param transactionId The id for the transaction.
+     * @param bufferId      The id for the buffer.
+     * @param timestampUs   The timestamp of the buffer is being sent.
+     * @param handle        The native handle to the allocated buffer. handle
+     *                      should be cloned before use.
+     * @param buffer        The received buffer.
+     *
+     * @return OK when a buffer was received successfully.
+     *         NOT_FOUND when the specified connection was not found.
+     *         NO_MEMORY when there is no memory.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus receive(ConnectionId connectionId,
+                         TransactionId transactionId,
+                         BufferId bufferId,
+                         int64_t timestampUs,
+                          native_handle_t **handle,
+                         std::shared_ptr<BufferPoolData> *buffer);
+
+    /**
+     * Posts a buffer transfer transaction to the buffer pool. Sends a buffer
+     * to other remote clients(connection) after this call has been succeeded.
+     *
+     * @param receiverId    The id of the receiving connection.
+     * @param buffer        to transfer
+     * @param transactionId Id of the transfer transaction.
+     * @param timestampUs   The timestamp of the buffer transaction is being
+     *                      posted.
+     *
+     * @return OK when a buffer transaction was posted successfully.
+     *         NOT_FOUND when the sending connection was not found.
+     *         CRITICAL_ERROR otherwise.
+     */
+    ResultStatus postSend(ConnectionId receiverId,
+                          const std::shared_ptr<BufferPoolData> &buffer,
+                          TransactionId *transactionId,
+                          int64_t *timestampUs);
+
+    /**
+     *  Time out inactive lingering connections and close.
+     */
+    void cleanUp();
+
+    /** Destructs the manager of buffer pool clients.  */
+    ~ClientManager();
+private:
+    static sp<ClientManager> sInstance;
+    static std::mutex sInstanceLock;
+
+    class Impl;
+    const std::unique_ptr<Impl> mImpl;
+
+    ClientManager();
+};
+
+}  // namespace implementation
+}  // namespace V2_0
+}  // namespace bufferpool
+}  // namespace media
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_MEDIA_BUFFERPOOL_V2_0_CLIENTMANAGER_H
diff --git a/media/bufferpool/aidl/default/tests/BufferpoolUnitTest.cpp b/media/bufferpool/aidl/default/tests/BufferpoolUnitTest.cpp
new file mode 100644
index 0000000..b448405
--- /dev/null
+++ b/media/bufferpool/aidl/default/tests/BufferpoolUnitTest.cpp
@@ -0,0 +1,541 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//#define LOG_NDEBUG 0
+#define LOG_TAG "BufferpoolUnitTest"
+#include <utils/Log.h>
+
+#include <binder/ProcessState.h>
+#include <bufferpool/ClientManager.h>
+#include <gtest/gtest.h>
+#include <hidl/LegacySupport.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unordered_set>
+#include <vector>
+#include "allocator.h"
+
+using android::hardware::configureRpcThreadpool;
+using android::hardware::media::bufferpool::BufferPoolData;
+using android::hardware::media::bufferpool::V2_0::IClientManager;
+using android::hardware::media::bufferpool::V2_0::ResultStatus;
+using android::hardware::media::bufferpool::V2_0::implementation::BufferId;
+using android::hardware::media::bufferpool::V2_0::implementation::ClientManager;
+using android::hardware::media::bufferpool::V2_0::implementation::ConnectionId;
+using android::hardware::media::bufferpool::V2_0::implementation::TransactionId;
+
+using namespace android;
+
+// communication message types between processes.
+enum PipeCommand : int32_t {
+    INIT,
+    TRANSFER,
+    STOP,
+
+    INIT_OK,
+    INIT_ERROR,
+    TRANSFER_OK,
+    TRANSFER_ERROR,
+    STOP_OK,
+    STOP_ERROR,
+};
+
+// communication message between processes.
+union PipeMessage {
+    struct {
+        int32_t command;
+        int32_t memsetValue;
+        BufferId bufferId;
+        ConnectionId connectionId;
+        TransactionId transactionId;
+        int64_t timestampUs;
+    } data;
+    char array[0];
+};
+
+static int32_t kNumIterationCount = 10;
+
+class BufferpoolTest {
+  public:
+    BufferpoolTest() : mConnectionValid(false), mManager(nullptr), mAllocator(nullptr) {
+        mConnectionId = -1;
+        mReceiverId = -1;
+    }
+
+    ~BufferpoolTest() {
+        if (mConnectionValid) {
+            mManager->close(mConnectionId);
+        }
+    }
+
+  protected:
+    bool mConnectionValid;
+    ConnectionId mConnectionId;
+    ConnectionId mReceiverId;
+
+    android::sp<ClientManager> mManager;
+    std::shared_ptr<BufferPoolAllocator> mAllocator;
+
+    void setupBufferpoolManager();
+};
+
+void BufferpoolTest::setupBufferpoolManager() {
+    // retrieving per process bufferpool object sp<ClientManager>
+    mManager = ClientManager::getInstance();
+    ASSERT_NE(mManager, nullptr) << "unable to get ClientManager\n";
+
+    mAllocator = std::make_shared<TestBufferPoolAllocator>();
+    ASSERT_NE(mAllocator, nullptr) << "unable to create TestBufferPoolAllocator\n";
+
+    // set-up local bufferpool connection for sender
+    ResultStatus status = mManager->create(mAllocator, &mConnectionId);
+    ASSERT_EQ(status, ResultStatus::OK)
+            << "unable to set-up local bufferpool connection for sender\n";
+    mConnectionValid = true;
+}
+
+class BufferpoolUnitTest : public BufferpoolTest, public ::testing::Test {
+  public:
+    virtual void SetUp() override { setupBufferpoolManager(); }
+
+    virtual void TearDown() override {}
+};
+
+class BufferpoolFunctionalityTest : public BufferpoolTest, public ::testing::Test {
+  public:
+    virtual void SetUp() override {
+        mReceiverPid = -1;
+
+        ASSERT_TRUE(pipe(mCommandPipeFds) == 0) << "pipe connection failed for commandPipe\n";
+        ASSERT_TRUE(pipe(mResultPipeFds) == 0) << "pipe connection failed for resultPipe\n";
+
+        mReceiverPid = fork();
+        ASSERT_TRUE(mReceiverPid >= 0) << "fork failed\n";
+
+        if (mReceiverPid == 0) {
+            doReceiver();
+            // In order to ignore gtest behaviour, wait for being killed from tearDown
+            pause();
+        }
+        setupBufferpoolManager();
+    }
+
+    virtual void TearDown() override {
+        if (mReceiverPid > 0) {
+            kill(mReceiverPid, SIGKILL);
+            int wstatus;
+            wait(&wstatus);
+        }
+    }
+
+  protected:
+    pid_t mReceiverPid;
+    int mCommandPipeFds[2];
+    int mResultPipeFds[2];
+
+    bool sendMessage(int* pipes, const PipeMessage& message) {
+        int ret = write(pipes[1], message.array, sizeof(PipeMessage));
+        return ret == sizeof(PipeMessage);
+    }
+
+    bool receiveMessage(int* pipes, PipeMessage* message) {
+        int ret = read(pipes[0], message->array, sizeof(PipeMessage));
+        return ret == sizeof(PipeMessage);
+    }
+
+    void doReceiver();
+};
+
+void BufferpoolFunctionalityTest::doReceiver() {
+    // Configures the threadpool used for handling incoming RPC calls in this process.
+    configureRpcThreadpool(1 /*threads*/, false /*willJoin*/);
+    bool receiverRunning = true;
+    while (receiverRunning) {
+        PipeMessage message;
+        receiveMessage(mCommandPipeFds, &message);
+        ResultStatus err = ResultStatus::OK;
+        switch (message.data.command) {
+            case PipeCommand::INIT: {
+                // receiver manager creation
+                mManager = ClientManager::getInstance();
+                if (!mManager) {
+                    message.data.command = PipeCommand::INIT_ERROR;
+                    sendMessage(mResultPipeFds, message);
+                    return;
+                }
+
+                android::status_t status = mManager->registerAsService();
+                if (status != android::OK) {
+                    message.data.command = PipeCommand::INIT_ERROR;
+                    sendMessage(mResultPipeFds, message);
+                    return;
+                }
+                message.data.command = PipeCommand::INIT_OK;
+                sendMessage(mResultPipeFds, message);
+                break;
+            }
+            case PipeCommand::TRANSFER: {
+                native_handle_t* receiveHandle = nullptr;
+                std::shared_ptr<BufferPoolData> receiveBuffer;
+                err = mManager->receive(message.data.connectionId, message.data.transactionId,
+                                        message.data.bufferId, message.data.timestampUs,
+                                        &receiveHandle, &receiveBuffer);
+                if (err != ResultStatus::OK) {
+                    message.data.command = PipeCommand::TRANSFER_ERROR;
+                    sendMessage(mResultPipeFds, message);
+                    return;
+                }
+                if (!TestBufferPoolAllocator::Verify(receiveHandle, message.data.memsetValue)) {
+                    message.data.command = PipeCommand::TRANSFER_ERROR;
+                    sendMessage(mResultPipeFds, message);
+                    return;
+                }
+                if (receiveHandle) {
+                    native_handle_close(receiveHandle);
+                    native_handle_delete(receiveHandle);
+                }
+                receiveHandle = nullptr;
+                receiveBuffer.reset();
+                message.data.command = PipeCommand::TRANSFER_OK;
+                sendMessage(mResultPipeFds, message);
+                break;
+            }
+            case PipeCommand::STOP: {
+                err = mManager->close(message.data.connectionId);
+                if (err != ResultStatus::OK) {
+                    message.data.command = PipeCommand::STOP_ERROR;
+                    sendMessage(mResultPipeFds, message);
+                    return;
+                }
+                message.data.command = PipeCommand::STOP_OK;
+                sendMessage(mResultPipeFds, message);
+                receiverRunning = false;
+                break;
+            }
+            default:
+                ALOGE("unknown command. try again");
+                break;
+        }
+    }
+}
+
+// Buffer allocation test.
+// Check whether each buffer allocation is done successfully with unique buffer id.
+TEST_F(BufferpoolUnitTest, AllocateBuffer) {
+    std::vector<uint8_t> vecParams;
+    getTestAllocatorParams(&vecParams);
+
+    std::vector<std::shared_ptr<BufferPoolData>> buffers{};
+    std::vector<native_handle_t*> allocHandle{};
+    ResultStatus status;
+    for (int i = 0; i < kNumIterationCount; ++i) {
+        native_handle_t* handle = nullptr;
+        std::shared_ptr<BufferPoolData> buffer{};
+        status = mManager->allocate(mConnectionId, vecParams, &handle, &buffer);
+        ASSERT_EQ(status, ResultStatus::OK) << "allocate failed for " << i << "iteration";
+
+        buffers.push_back(std::move(buffer));
+        if (handle) {
+            allocHandle.push_back(std::move(handle));
+        }
+    }
+
+    for (int i = 0; i < kNumIterationCount; ++i) {
+        for (int j = i + 1; j < kNumIterationCount; ++j) {
+            ASSERT_TRUE(buffers[i]->mId != buffers[j]->mId) << "allocated buffers are not unique";
+        }
+    }
+    // delete the buffer handles
+    for (auto handle : allocHandle) {
+        native_handle_close(handle);
+        native_handle_delete(handle);
+    }
+    // clear the vectors
+    buffers.clear();
+    allocHandle.clear();
+}
+
+// Buffer recycle test.
+// Check whether de-allocated buffers are recycled.
+TEST_F(BufferpoolUnitTest, RecycleBuffer) {
+    std::vector<uint8_t> vecParams;
+    getTestAllocatorParams(&vecParams);
+
+    ResultStatus status;
+    std::vector<BufferId> bid{};
+    std::vector<native_handle_t*> allocHandle{};
+    for (int i = 0; i < kNumIterationCount; ++i) {
+        native_handle_t* handle = nullptr;
+        std::shared_ptr<BufferPoolData> buffer;
+        status = mManager->allocate(mConnectionId, vecParams, &handle, &buffer);
+        ASSERT_EQ(status, ResultStatus::OK) << "allocate failed for " << i << "iteration";
+
+        bid.push_back(buffer->mId);
+        if (handle) {
+            allocHandle.push_back(std::move(handle));
+        }
+        buffer.reset();
+    }
+
+    std::unordered_set<BufferId> set(bid.begin(), bid.end());
+    ASSERT_EQ(set.size(), 1) << "buffers are not recycled properly";
+
+    // delete the buffer handles
+    for (auto handle : allocHandle) {
+        native_handle_close(handle);
+        native_handle_delete(handle);
+    }
+    allocHandle.clear();
+}
+
+// Validate cache evict and invalidate APIs.
+TEST_F(BufferpoolUnitTest, FlushTest) {
+    std::vector<uint8_t> vecParams;
+    getTestAllocatorParams(&vecParams);
+
+    ResultStatus status = mManager->registerSender(mManager, mConnectionId, &mReceiverId);
+    ASSERT_TRUE(status == ResultStatus::ALREADY_EXISTS && mReceiverId == mConnectionId);
+
+    // testing empty flush
+    status = mManager->flush(mConnectionId);
+    ASSERT_EQ(status, ResultStatus::OK) << "failed to flush connection : " << mConnectionId;
+
+    std::vector<std::shared_ptr<BufferPoolData>> senderBuffer{};
+    std::vector<native_handle_t*> allocHandle{};
+    std::vector<TransactionId> tid{};
+    std::vector<int64_t> timestampUs{};
+
+    std::map<TransactionId, BufferId> bufferMap{};
+
+    for (int i = 0; i < kNumIterationCount; i++) {
+        int64_t postUs;
+        TransactionId transactionId;
+        native_handle_t* handle = nullptr;
+        std::shared_ptr<BufferPoolData> buffer{};
+        status = mManager->allocate(mConnectionId, vecParams, &handle, &buffer);
+        ASSERT_EQ(status, ResultStatus::OK) << "allocate failed for " << i << " iteration";
+
+        ASSERT_TRUE(TestBufferPoolAllocator::Fill(handle, i));
+
+        status = mManager->postSend(mReceiverId, buffer, &transactionId, &postUs);
+        ASSERT_EQ(status, ResultStatus::OK) << "unable to post send transaction on bufferpool";
+
+        timestampUs.push_back(postUs);
+        tid.push_back(transactionId);
+        bufferMap.insert({transactionId, buffer->mId});
+
+        senderBuffer.push_back(std::move(buffer));
+        if (handle) {
+            allocHandle.push_back(std::move(handle));
+        }
+        buffer.reset();
+    }
+
+    status = mManager->flush(mConnectionId);
+    ASSERT_EQ(status, ResultStatus::OK) << "failed to flush connection : " << mConnectionId;
+
+    std::shared_ptr<BufferPoolData> receiverBuffer{};
+    native_handle_t* recvHandle = nullptr;
+    for (int i = 0; i < kNumIterationCount; i++) {
+        status = mManager->receive(mReceiverId, tid[i], senderBuffer[i]->mId, timestampUs[i],
+                                   &recvHandle, &receiverBuffer);
+        ASSERT_EQ(status, ResultStatus::OK) << "receive failed for buffer " << senderBuffer[i]->mId;
+
+        // find the buffer id from transaction id
+        auto findIt = bufferMap.find(tid[i]);
+        ASSERT_NE(findIt, bufferMap.end()) << "inconsistent buffer mapping";
+
+        // buffer id received must be same as the buffer id sent
+        ASSERT_EQ(findIt->second, receiverBuffer->mId) << "invalid buffer received";
+
+        ASSERT_TRUE(TestBufferPoolAllocator::Verify(recvHandle, i))
+                << "Message received not same as that sent";
+
+        bufferMap.erase(findIt);
+        if (recvHandle) {
+            native_handle_close(recvHandle);
+            native_handle_delete(recvHandle);
+        }
+        recvHandle = nullptr;
+        receiverBuffer.reset();
+    }
+
+    ASSERT_EQ(bufferMap.size(), 0) << "buffers received is less than the number of buffers sent";
+
+    for (auto handle : allocHandle) {
+        native_handle_close(handle);
+        native_handle_delete(handle);
+    }
+    allocHandle.clear();
+    senderBuffer.clear();
+    timestampUs.clear();
+}
+
+// Buffer transfer test between processes.
+TEST_F(BufferpoolFunctionalityTest, TransferBuffer) {
+    // initialize the receiver
+    PipeMessage message;
+    message.data.command = PipeCommand::INIT;
+    sendMessage(mCommandPipeFds, message);
+    ASSERT_TRUE(receiveMessage(mResultPipeFds, &message)) << "receiveMessage failed\n";
+    ASSERT_EQ(message.data.command, PipeCommand::INIT_OK) << "receiver init failed";
+
+    android::sp<IClientManager> receiver = IClientManager::getService();
+    ASSERT_NE(receiver, nullptr) << "getService failed for receiver\n";
+
+    ConnectionId receiverId;
+    ResultStatus status = mManager->registerSender(receiver, mConnectionId, &receiverId);
+    ASSERT_EQ(status, ResultStatus::OK)
+            << "registerSender failed for connection id " << mConnectionId << "\n";
+
+    std::vector<uint8_t> vecParams;
+    getTestAllocatorParams(&vecParams);
+
+    for (int i = 0; i < kNumIterationCount; ++i) {
+        native_handle_t* handle = nullptr;
+        std::shared_ptr<BufferPoolData> buffer;
+        status = mManager->allocate(mConnectionId, vecParams, &handle, &buffer);
+        ASSERT_EQ(status, ResultStatus::OK) << "allocate failed for " << i << "iteration";
+
+        ASSERT_TRUE(TestBufferPoolAllocator::Fill(handle, i))
+                << "Fill fail for buffer handle " << handle << "\n";
+
+        // send the buffer to the receiver
+        int64_t postUs;
+        TransactionId transactionId;
+        status = mManager->postSend(receiverId, buffer, &transactionId, &postUs);
+        ASSERT_EQ(status, ResultStatus::OK)
+                << "postSend failed for receiver " << receiverId << "\n";
+
+        // PipeMessage message;
+        message.data.command = PipeCommand::TRANSFER;
+        message.data.memsetValue = i;
+        message.data.bufferId = buffer->mId;
+        message.data.connectionId = receiverId;
+        message.data.transactionId = transactionId;
+        message.data.timestampUs = postUs;
+        sendMessage(mCommandPipeFds, message);
+        // delete buffer handle
+        if (handle) {
+            native_handle_close(handle);
+            native_handle_delete(handle);
+        }
+        ASSERT_TRUE(receiveMessage(mResultPipeFds, &message)) << "receiveMessage failed\n";
+        ASSERT_EQ(message.data.command, PipeCommand::TRANSFER_OK)
+                << "received error during buffer transfer\n";
+    }
+    message.data.command = PipeCommand::STOP;
+    sendMessage(mCommandPipeFds, message);
+    ASSERT_TRUE(receiveMessage(mResultPipeFds, &message)) << "receiveMessage failed\n";
+    ASSERT_EQ(message.data.command, PipeCommand::STOP_OK)
+            << "received error during buffer transfer\n";
+}
+
+/* Validate bufferpool for following corner cases:
+ 1. invalid connectionID
+ 2. invalid receiver
+ 3. when sender is not registered
+ 4. when connection is closed
+*/
+// TODO: Enable when the issue in b/212196495 is fixed
+TEST_F(BufferpoolFunctionalityTest, DISABLED_ValidityTest) {
+    std::vector<uint8_t> vecParams;
+    getTestAllocatorParams(&vecParams);
+
+    std::shared_ptr<BufferPoolData> senderBuffer;
+    native_handle_t* allocHandle = nullptr;
+
+    // call allocate() on a random connection id
+    ConnectionId randomId = rand();
+    ResultStatus status = mManager->allocate(randomId, vecParams, &allocHandle, &senderBuffer);
+    EXPECT_TRUE(status == ResultStatus::NOT_FOUND);
+
+    // initialize the receiver
+    PipeMessage message;
+    message.data.command = PipeCommand::INIT;
+    sendMessage(mCommandPipeFds, message);
+    ASSERT_TRUE(receiveMessage(mResultPipeFds, &message)) << "receiveMessage failed\n";
+    ASSERT_EQ(message.data.command, PipeCommand::INIT_OK) << "receiver init failed";
+
+    allocHandle = nullptr;
+    senderBuffer.reset();
+    status = mManager->allocate(mConnectionId, vecParams, &allocHandle, &senderBuffer);
+
+    ASSERT_TRUE(TestBufferPoolAllocator::Fill(allocHandle, 0x77));
+
+    // send buffers w/o registering sender
+    int64_t postUs;
+    TransactionId transactionId;
+
+    // random receiver
+    status = mManager->postSend(randomId, senderBuffer, &transactionId, &postUs);
+    ASSERT_NE(status, ResultStatus::OK) << "bufferpool shouldn't allow send on random receiver";
+
+    // establish connection
+    android::sp<IClientManager> receiver = IClientManager::getService();
+    ASSERT_NE(receiver, nullptr) << "getService failed for receiver\n";
+
+    ConnectionId receiverId;
+    status = mManager->registerSender(receiver, mConnectionId, &receiverId);
+    ASSERT_EQ(status, ResultStatus::OK)
+            << "registerSender failed for connection id " << mConnectionId << "\n";
+
+    allocHandle = nullptr;
+    senderBuffer.reset();
+    status = mManager->allocate(mConnectionId, vecParams, &allocHandle, &senderBuffer);
+    ASSERT_EQ(status, ResultStatus::OK) << "allocate failed for connection " << mConnectionId;
+
+    ASSERT_TRUE(TestBufferPoolAllocator::Fill(allocHandle, 0x88));
+
+    // send the buffer to the receiver
+    status = mManager->postSend(receiverId, senderBuffer, &transactionId, &postUs);
+    ASSERT_EQ(status, ResultStatus::OK) << "postSend failed for receiver " << receiverId << "\n";
+
+    // PipeMessage message;
+    message.data.command = PipeCommand::TRANSFER;
+    message.data.memsetValue = 0x88;
+    message.data.bufferId = senderBuffer->mId;
+    message.data.connectionId = receiverId;
+    message.data.transactionId = transactionId;
+    message.data.timestampUs = postUs;
+    sendMessage(mCommandPipeFds, message);
+    ASSERT_TRUE(receiveMessage(mResultPipeFds, &message)) << "receiveMessage failed\n";
+    ASSERT_EQ(message.data.command, PipeCommand::TRANSFER_OK)
+            << "received error during buffer transfer\n";
+
+    if (allocHandle) {
+        native_handle_close(allocHandle);
+        native_handle_delete(allocHandle);
+    }
+
+    message.data.command = PipeCommand::STOP;
+    sendMessage(mCommandPipeFds, message);
+    ASSERT_TRUE(receiveMessage(mResultPipeFds, &message)) << "receiveMessage failed\n";
+    ASSERT_EQ(message.data.command, PipeCommand::STOP_OK)
+            << "received error during buffer transfer\n";
+
+    // try to send msg to closed connection
+    status = mManager->postSend(receiverId, senderBuffer, &transactionId, &postUs);
+    ASSERT_NE(status, ResultStatus::OK) << "bufferpool shouldn't allow send on closed connection";
+}
+
+int main(int argc, char** argv) {
+    android::hardware::details::setTrebleTestingOverride(true);
+    ::testing::InitGoogleTest(&argc, argv);
+    int status = RUN_ALL_TESTS();
+    ALOGV("Test result = %d\n", status);
+    return status;
+}
diff --git a/media/bufferpool/aidl/default/tests/allocator.cpp b/media/bufferpool/aidl/default/tests/allocator.cpp
new file mode 100644
index 0000000..25b08ef
--- /dev/null
+++ b/media/bufferpool/aidl/default/tests/allocator.cpp
@@ -0,0 +1,251 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <cutils/ashmem.h>
+#include <sys/mman.h>
+#include "allocator.h"
+
+union Params {
+  struct {
+    uint32_t capacity;
+  } data;
+  uint8_t array[0];
+  Params() : data{0} {}
+  Params(uint32_t size)
+      : data{size} {}
+};
+
+
+namespace {
+
+struct HandleAshmem : public native_handle_t {
+  HandleAshmem(int ashmemFd, size_t size)
+    : native_handle_t(cHeader),
+    mFds{ ashmemFd },
+    mInts{ int (size & 0xFFFFFFFF), int((uint64_t(size) >> 32) & 0xFFFFFFFF), kMagic } {}
+
+  int ashmemFd() const { return mFds.mAshmem; }
+  size_t size() const {
+    return size_t(unsigned(mInts.mSizeLo))
+        | size_t(uint64_t(unsigned(mInts.mSizeHi)) << 32);
+  }
+
+  static bool isValid(const native_handle_t * const o);
+
+protected:
+  struct {
+    int mAshmem;
+  } mFds;
+  struct {
+    int mSizeLo;
+    int mSizeHi;
+    int mMagic;
+  } mInts;
+
+private:
+  enum {
+    kMagic = 'ahm\x00',
+    numFds = sizeof(mFds) / sizeof(int),
+    numInts = sizeof(mInts) / sizeof(int),
+    version = sizeof(native_handle_t)
+  };
+  const static native_handle_t cHeader;
+};
+
+const native_handle_t HandleAshmem::cHeader = {
+  HandleAshmem::version,
+  HandleAshmem::numFds,
+  HandleAshmem::numInts,
+  {}
+};
+
+bool HandleAshmem::isValid(const native_handle_t * const o) {
+  if (!o || memcmp(o, &cHeader, sizeof(cHeader))) {
+    return false;
+  }
+  const HandleAshmem *other = static_cast<const HandleAshmem*>(o);
+  return other->mInts.mMagic == kMagic;
+}
+
+class AllocationAshmem {
+private:
+  AllocationAshmem(int ashmemFd, size_t capacity, bool res)
+    : mHandle(ashmemFd, capacity),
+      mInit(res) {}
+
+public:
+  static AllocationAshmem *Alloc(size_t size) {
+    constexpr static const char *kAllocationTag = "bufferpool_test";
+    int ashmemFd = ashmem_create_region(kAllocationTag, size);
+    return new AllocationAshmem(ashmemFd, size, ashmemFd >= 0);
+  }
+
+  ~AllocationAshmem() {
+    if (mInit) {
+      native_handle_close(&mHandle);
+    }
+  }
+
+  const HandleAshmem *handle() {
+    return &mHandle;
+  }
+
+private:
+  HandleAshmem mHandle;
+  bool mInit;
+  // TODO: mapping and map fd
+};
+
+struct AllocationDtor {
+  AllocationDtor(const std::shared_ptr<AllocationAshmem> &alloc)
+      : mAlloc(alloc) {}
+
+  void operator()(BufferPoolAllocation *poolAlloc) { delete poolAlloc; }
+
+  const std::shared_ptr<AllocationAshmem> mAlloc;
+};
+
+}
+
+void IpcMutex::init() {
+  pthread_mutexattr_t mattr;
+  pthread_mutexattr_init(&mattr);
+  pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
+  pthread_mutex_init(&lock, &mattr);
+  pthread_mutexattr_destroy(&mattr);
+
+  pthread_condattr_t cattr;
+  pthread_condattr_init(&cattr);
+  pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED);
+  pthread_cond_init(&cond, &cattr);
+  pthread_condattr_destroy(&cattr);
+}
+
+IpcMutex *IpcMutex::Import(void *pMutex) {
+  return reinterpret_cast<IpcMutex *>(pMutex);
+}
+
+
+ResultStatus TestBufferPoolAllocator::allocate(
+    const std::vector<uint8_t> &params,
+    std::shared_ptr<BufferPoolAllocation> *alloc,
+    size_t *allocSize) {
+  Params ashmemParams;
+  memcpy(&ashmemParams, params.data(), std::min(sizeof(Params), params.size()));
+
+  std::shared_ptr<AllocationAshmem> ashmemAlloc =
+      std::shared_ptr<AllocationAshmem>(
+          AllocationAshmem::Alloc(ashmemParams.data.capacity));
+  if (ashmemAlloc) {
+    BufferPoolAllocation *ptr = new BufferPoolAllocation(ashmemAlloc->handle());
+    if (ptr) {
+      *alloc = std::shared_ptr<BufferPoolAllocation>(ptr, AllocationDtor(ashmemAlloc));
+      if (*alloc) {
+          *allocSize = ashmemParams.data.capacity;
+          return ResultStatus::OK;
+      }
+      delete ptr;
+      return ResultStatus::NO_MEMORY;
+    }
+  }
+  return ResultStatus::CRITICAL_ERROR;
+}
+
+bool TestBufferPoolAllocator::compatible(const std::vector<uint8_t> &newParams,
+                                        const std::vector<uint8_t> &oldParams) {
+  size_t newSize = newParams.size();
+  size_t oldSize = oldParams.size();
+  if (newSize == oldSize) {
+    for (size_t i = 0; i < newSize; ++i) {
+      if (newParams[i] != oldParams[i]) {
+        return false;
+      }
+    }
+    return true;
+  }
+  return false;
+}
+
+bool TestBufferPoolAllocator::Fill(const native_handle_t *handle, const unsigned char val) {
+  if (!HandleAshmem::isValid(handle)) {
+    return false;
+  }
+  const HandleAshmem *o = static_cast<const HandleAshmem*>(handle);
+  unsigned char *ptr = (unsigned char *)mmap(
+      NULL, o->size(), PROT_READ|PROT_WRITE, MAP_SHARED, o->ashmemFd(), 0);
+
+  if (ptr != MAP_FAILED) {
+    for (size_t i = 0; i < o->size(); ++i) {
+      ptr[i] = val;
+    }
+    munmap(ptr, o->size());
+    return true;
+  }
+  return false;
+}
+
+bool TestBufferPoolAllocator::Verify(const native_handle_t *handle, const unsigned char val) {
+  if (!HandleAshmem::isValid(handle)) {
+    return false;
+  }
+  const HandleAshmem *o = static_cast<const HandleAshmem*>(handle);
+  unsigned char *ptr = (unsigned char *)mmap(
+      NULL, o->size(), PROT_READ, MAP_SHARED, o->ashmemFd(), 0);
+
+  if (ptr != MAP_FAILED) {
+    bool res = true;
+    for (size_t i = 0; i < o->size(); ++i) {
+      if (ptr[i] != val) {
+        res = false;
+        break;
+      }
+    }
+    munmap(ptr, o->size());
+    return res;
+  }
+  return false;
+}
+
+bool TestBufferPoolAllocator::MapMemoryForMutex(const native_handle_t *handle, void **mem) {
+  if (!HandleAshmem::isValid(handle)) {
+    return false;
+  }
+  const HandleAshmem *o = static_cast<const HandleAshmem*>(handle);
+  *mem = mmap(
+      NULL, o->size(), PROT_READ|PROT_WRITE, MAP_SHARED, o->ashmemFd(), 0);
+  if (*mem == MAP_FAILED || *mem == nullptr) {
+    return false;
+  }
+  return true;
+}
+
+bool TestBufferPoolAllocator::UnmapMemoryForMutex(void *mem) {
+  munmap(mem, sizeof(IpcMutex));
+  return true;
+}
+
+void getTestAllocatorParams(std::vector<uint8_t> *params) {
+  constexpr static int kAllocationSize = 1024 * 10;
+  Params ashmemParams(kAllocationSize);
+
+  params->assign(ashmemParams.array, ashmemParams.array + sizeof(ashmemParams));
+}
+
+void getIpcMutexParams(std::vector<uint8_t> *params) {
+  Params ashmemParams(sizeof(IpcMutex));
+
+  params->assign(ashmemParams.array, ashmemParams.array + sizeof(ashmemParams));
+}
diff --git a/media/bufferpool/aidl/default/tests/allocator.h b/media/bufferpool/aidl/default/tests/allocator.h
new file mode 100644
index 0000000..862d1a5
--- /dev/null
+++ b/media/bufferpool/aidl/default/tests/allocator.h
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef VNDK_HIDL_BUFFERPOOL_V2_0_ALLOCATOR_H
+#define VNDK_HIDL_BUFFERPOOL_V2_0_ALLOCATOR_H
+
+#include <pthread.h>
+#include <bufferpool/BufferPoolTypes.h>
+
+using android::hardware::media::bufferpool::V2_0::ResultStatus;
+using android::hardware::media::bufferpool::V2_0::implementation::
+    BufferPoolAllocation;
+using android::hardware::media::bufferpool::V2_0::implementation::
+    BufferPoolAllocator;
+
+struct IpcMutex {
+  pthread_mutex_t lock;
+  pthread_cond_t cond;
+  int counter = 0;
+  bool signalled = false;
+
+  void init();
+
+  static IpcMutex *Import(void *mem);
+};
+
+// buffer allocator for the tests
+class TestBufferPoolAllocator : public BufferPoolAllocator {
+ public:
+  TestBufferPoolAllocator() {}
+
+  ~TestBufferPoolAllocator() override {}
+
+  ResultStatus allocate(const std::vector<uint8_t> &params,
+                        std::shared_ptr<BufferPoolAllocation> *alloc,
+                        size_t *allocSize) override;
+
+  bool compatible(const std::vector<uint8_t> &newParams,
+                  const std::vector<uint8_t> &oldParams) override;
+
+  static bool Fill(const native_handle_t *handle, const unsigned char val);
+
+  static bool Verify(const native_handle_t *handle, const unsigned char val);
+
+  static bool MapMemoryForMutex(const native_handle_t *handle, void **mem);
+
+  static bool UnmapMemoryForMutex(void *mem);
+};
+
+// retrieve buffer allocator paramters
+void getTestAllocatorParams(std::vector<uint8_t> *params);
+
+void getIpcMutexParams(std::vector<uint8_t> *params);
+
+#endif  // VNDK_HIDL_BUFFERPOOL_V2_0_ALLOCATOR_H
diff --git a/media/bufferpool/aidl/default/tests/cond.cpp b/media/bufferpool/aidl/default/tests/cond.cpp
new file mode 100644
index 0000000..21beea8
--- /dev/null
+++ b/media/bufferpool/aidl/default/tests/cond.cpp
@@ -0,0 +1,269 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "buffferpool_unit_test"
+
+#include <gtest/gtest.h>
+
+#include <android-base/logging.h>
+#include <binder/ProcessState.h>
+#include <bufferpool/ClientManager.h>
+#include <errno.h>
+#include <hidl/HidlSupport.h>
+#include <hidl/HidlTransportSupport.h>
+#include <hidl/LegacySupport.h>
+#include <hidl/Status.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <iostream>
+#include <memory>
+#include <vector>
+#include "allocator.h"
+
+using android::hardware::configureRpcThreadpool;
+using android::hardware::hidl_handle;
+using android::hardware::media::bufferpool::V2_0::IClientManager;
+using android::hardware::media::bufferpool::V2_0::ResultStatus;
+using android::hardware::media::bufferpool::V2_0::implementation::BufferId;
+using android::hardware::media::bufferpool::V2_0::implementation::ClientManager;
+using android::hardware::media::bufferpool::V2_0::implementation::ConnectionId;
+using android::hardware::media::bufferpool::V2_0::implementation::TransactionId;
+using android::hardware::media::bufferpool::BufferPoolData;
+
+namespace {
+
+// communication message types between processes.
+enum PipeCommand : int32_t {
+    INIT_OK = 0,
+    INIT_ERROR,
+    SEND,
+    RECEIVE_OK,
+    RECEIVE_ERROR,
+};
+
+// communication message between processes.
+union PipeMessage {
+    struct  {
+        int32_t command;
+        BufferId bufferId;
+        ConnectionId connectionId;
+        TransactionId transactionId;
+        int64_t  timestampUs;
+    } data;
+    char array[0];
+};
+
+constexpr int kSignalInt = 200;
+
+// media.bufferpool test setup
+class BufferpoolMultiTest : public ::testing::Test {
+ public:
+  virtual void SetUp() override {
+    ResultStatus status;
+    mReceiverPid = -1;
+    mConnectionValid = false;
+
+    ASSERT_TRUE(pipe(mCommandPipeFds) == 0);
+    ASSERT_TRUE(pipe(mResultPipeFds) == 0);
+
+    mReceiverPid = fork();
+    ASSERT_TRUE(mReceiverPid >= 0);
+
+    if (mReceiverPid == 0) {
+      doReceiver();
+      // In order to ignore gtest behaviour, wait for being killed from
+      // tearDown
+      pause();
+    }
+
+    mManager = ClientManager::getInstance();
+    ASSERT_NE(mManager, nullptr);
+
+    mAllocator = std::make_shared<TestBufferPoolAllocator>();
+    ASSERT_TRUE((bool)mAllocator);
+
+    status = mManager->create(mAllocator, &mConnectionId);
+    ASSERT_TRUE(status == ResultStatus::OK);
+    mConnectionValid = true;
+  }
+
+  virtual void TearDown() override {
+    if (mReceiverPid > 0) {
+      kill(mReceiverPid, SIGKILL);
+      int wstatus;
+      wait(&wstatus);
+    }
+
+    if (mConnectionValid) {
+      mManager->close(mConnectionId);
+    }
+  }
+
+ protected:
+  static void description(const std::string& description) {
+    RecordProperty("description", description);
+  }
+
+  android::sp<ClientManager> mManager;
+  std::shared_ptr<BufferPoolAllocator> mAllocator;
+  bool mConnectionValid;
+  ConnectionId mConnectionId;
+  pid_t mReceiverPid;
+  int mCommandPipeFds[2];
+  int mResultPipeFds[2];
+
+  bool sendMessage(int *pipes, const PipeMessage &message) {
+    int ret = write(pipes[1], message.array, sizeof(PipeMessage));
+    return ret == sizeof(PipeMessage);
+  }
+
+  bool receiveMessage(int *pipes, PipeMessage *message) {
+    int ret = read(pipes[0], message->array, sizeof(PipeMessage));
+    return ret == sizeof(PipeMessage);
+  }
+
+  void doReceiver() {
+    configureRpcThreadpool(1, false);
+    PipeMessage message;
+    mManager = ClientManager::getInstance();
+    if (!mManager) {
+      message.data.command = PipeCommand::INIT_ERROR;
+      sendMessage(mResultPipeFds, message);
+      return;
+    }
+    android::status_t status = mManager->registerAsService();
+    if (status != android::OK) {
+      message.data.command = PipeCommand::INIT_ERROR;
+      sendMessage(mResultPipeFds, message);
+      return;
+    }
+    message.data.command = PipeCommand::INIT_OK;
+    sendMessage(mResultPipeFds, message);
+
+    int val = 0;
+    receiveMessage(mCommandPipeFds, &message);
+    {
+      native_handle_t *rhandle = nullptr;
+      std::shared_ptr<BufferPoolData> rbuffer;
+      void *mem = nullptr;
+      IpcMutex *mutex = nullptr;
+      ResultStatus status = mManager->receive(
+          message.data.connectionId, message.data.transactionId,
+          message.data.bufferId, message.data.timestampUs, &rhandle, &rbuffer);
+      mManager->close(message.data.connectionId);
+      if (status != ResultStatus::OK) {
+          message.data.command = PipeCommand::RECEIVE_ERROR;
+          sendMessage(mResultPipeFds, message);
+          return;
+      }
+      if (!TestBufferPoolAllocator::MapMemoryForMutex(rhandle, &mem)) {
+          message.data.command = PipeCommand::RECEIVE_ERROR;
+          sendMessage(mResultPipeFds, message);
+          return;
+      }
+      mutex = IpcMutex::Import(mem);
+      pthread_mutex_lock(&(mutex->lock));
+      while (mutex->signalled != true) {
+          pthread_cond_wait(&(mutex->cond), &(mutex->lock));
+      }
+      val = mutex->counter;
+      pthread_mutex_unlock(&(mutex->lock));
+
+      (void)TestBufferPoolAllocator::UnmapMemoryForMutex(mem);
+      if (rhandle) {
+        native_handle_close(rhandle);
+        native_handle_delete(rhandle);
+      }
+    }
+    if (val == kSignalInt) {
+      message.data.command = PipeCommand::RECEIVE_OK;
+    } else {
+      message.data.command = PipeCommand::RECEIVE_ERROR;
+    }
+    sendMessage(mResultPipeFds, message);
+  }
+};
+
+// Buffer transfer test between processes.
+TEST_F(BufferpoolMultiTest, TransferBuffer) {
+  ResultStatus status;
+  PipeMessage message;
+
+  ASSERT_TRUE(receiveMessage(mResultPipeFds, &message));
+
+  android::sp<IClientManager> receiver = IClientManager::getService();
+  ConnectionId receiverId;
+  ASSERT_TRUE((bool)receiver);
+
+  status = mManager->registerSender(receiver, mConnectionId, &receiverId);
+  ASSERT_TRUE(status == ResultStatus::OK);
+  {
+    native_handle_t *shandle = nullptr;
+    std::shared_ptr<BufferPoolData> sbuffer;
+    TransactionId transactionId;
+    int64_t postUs;
+    std::vector<uint8_t> vecParams;
+    void *mem = nullptr;
+    IpcMutex *mutex = nullptr;
+
+    getIpcMutexParams(&vecParams);
+    status = mManager->allocate(mConnectionId, vecParams, &shandle, &sbuffer);
+    ASSERT_TRUE(status == ResultStatus::OK);
+
+    ASSERT_TRUE(TestBufferPoolAllocator::MapMemoryForMutex(shandle, &mem));
+
+    mutex = new(mem) IpcMutex();
+    mutex->init();
+
+    status = mManager->postSend(receiverId, sbuffer, &transactionId, &postUs);
+    ASSERT_TRUE(status == ResultStatus::OK);
+
+    message.data.command = PipeCommand::SEND;
+    message.data.bufferId = sbuffer->mId;
+    message.data.connectionId = receiverId;
+    message.data.transactionId = transactionId;
+    message.data.timestampUs = postUs;
+    sendMessage(mCommandPipeFds, message);
+    for (int i=0; i < 200000000; ++i) {
+      // no-op in order to ensure
+      // pthread_cond_wait is called before pthread_cond_signal
+    }
+    pthread_mutex_lock(&(mutex->lock));
+    mutex->counter = kSignalInt;
+    mutex->signalled = true;
+    pthread_cond_signal(&(mutex->cond));
+    pthread_mutex_unlock(&(mutex->lock));
+    (void)TestBufferPoolAllocator::UnmapMemoryForMutex(mem);
+    if (shandle) {
+      native_handle_close(shandle);
+      native_handle_delete(shandle);
+    }
+  }
+  EXPECT_TRUE(receiveMessage(mResultPipeFds, &message));
+  EXPECT_TRUE(message.data.command == PipeCommand::RECEIVE_OK);
+}
+
+}  // anonymous namespace
+
+int main(int argc, char** argv) {
+  android::hardware::details::setTrebleTestingOverride(true);
+  ::testing::InitGoogleTest(&argc, argv);
+  int status = RUN_ALL_TESTS();
+  LOG(INFO) << "Test result = " << status;
+  return status;
+}
diff --git a/media/bufferpool/aidl/default/tests/multi.cpp b/media/bufferpool/aidl/default/tests/multi.cpp
new file mode 100644
index 0000000..43b0a8c
--- /dev/null
+++ b/media/bufferpool/aidl/default/tests/multi.cpp
@@ -0,0 +1,235 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "buffferpool_unit_test"
+
+#include <gtest/gtest.h>
+
+#include <android-base/logging.h>
+#include <binder/ProcessState.h>
+#include <bufferpool/ClientManager.h>
+#include <hidl/HidlSupport.h>
+#include <hidl/HidlTransportSupport.h>
+#include <hidl/LegacySupport.h>
+#include <hidl/Status.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <iostream>
+#include <memory>
+#include <vector>
+#include "allocator.h"
+
+using android::hardware::configureRpcThreadpool;
+using android::hardware::hidl_handle;
+using android::hardware::media::bufferpool::V2_0::IClientManager;
+using android::hardware::media::bufferpool::V2_0::ResultStatus;
+using android::hardware::media::bufferpool::V2_0::implementation::BufferId;
+using android::hardware::media::bufferpool::V2_0::implementation::ClientManager;
+using android::hardware::media::bufferpool::V2_0::implementation::ConnectionId;
+using android::hardware::media::bufferpool::V2_0::implementation::TransactionId;
+using android::hardware::media::bufferpool::BufferPoolData;
+
+namespace {
+
+// communication message types between processes.
+enum PipeCommand : int32_t {
+    INIT_OK = 0,
+    INIT_ERROR,
+    SEND,
+    RECEIVE_OK,
+    RECEIVE_ERROR,
+};
+
+// communication message between processes.
+union PipeMessage {
+    struct  {
+        int32_t command;
+        BufferId bufferId;
+        ConnectionId connectionId;
+        TransactionId transactionId;
+        int64_t  timestampUs;
+    } data;
+    char array[0];
+};
+
+// media.bufferpool test setup
+class BufferpoolMultiTest : public ::testing::Test {
+ public:
+  virtual void SetUp() override {
+    ResultStatus status;
+    mReceiverPid = -1;
+    mConnectionValid = false;
+
+    ASSERT_TRUE(pipe(mCommandPipeFds) == 0);
+    ASSERT_TRUE(pipe(mResultPipeFds) == 0);
+
+    mReceiverPid = fork();
+    ASSERT_TRUE(mReceiverPid >= 0);
+
+    if (mReceiverPid == 0) {
+      doReceiver();
+      // In order to ignore gtest behaviour, wait for being killed from
+      // tearDown
+      pause();
+    }
+
+    mManager = ClientManager::getInstance();
+    ASSERT_NE(mManager, nullptr);
+
+    mAllocator = std::make_shared<TestBufferPoolAllocator>();
+    ASSERT_TRUE((bool)mAllocator);
+
+    status = mManager->create(mAllocator, &mConnectionId);
+    ASSERT_TRUE(status == ResultStatus::OK);
+    mConnectionValid = true;
+  }
+
+  virtual void TearDown() override {
+    if (mReceiverPid > 0) {
+      kill(mReceiverPid, SIGKILL);
+      int wstatus;
+      wait(&wstatus);
+    }
+
+    if (mConnectionValid) {
+      mManager->close(mConnectionId);
+    }
+  }
+
+ protected:
+  static void description(const std::string& description) {
+    RecordProperty("description", description);
+  }
+
+  android::sp<ClientManager> mManager;
+  std::shared_ptr<BufferPoolAllocator> mAllocator;
+  bool mConnectionValid;
+  ConnectionId mConnectionId;
+  pid_t mReceiverPid;
+  int mCommandPipeFds[2];
+  int mResultPipeFds[2];
+
+  bool sendMessage(int *pipes, const PipeMessage &message) {
+    int ret = write(pipes[1], message.array, sizeof(PipeMessage));
+    return ret == sizeof(PipeMessage);
+  }
+
+  bool receiveMessage(int *pipes, PipeMessage *message) {
+    int ret = read(pipes[0], message->array, sizeof(PipeMessage));
+    return ret == sizeof(PipeMessage);
+  }
+
+  void doReceiver() {
+    configureRpcThreadpool(1, false);
+    PipeMessage message;
+    mManager = ClientManager::getInstance();
+    if (!mManager) {
+      message.data.command = PipeCommand::INIT_ERROR;
+      sendMessage(mResultPipeFds, message);
+      return;
+    }
+    android::status_t status = mManager->registerAsService();
+    if (status != android::OK) {
+      message.data.command = PipeCommand::INIT_ERROR;
+      sendMessage(mResultPipeFds, message);
+      return;
+    }
+    message.data.command = PipeCommand::INIT_OK;
+    sendMessage(mResultPipeFds, message);
+
+    receiveMessage(mCommandPipeFds, &message);
+    {
+      native_handle_t *rhandle = nullptr;
+      std::shared_ptr<BufferPoolData> rbuffer;
+      ResultStatus status = mManager->receive(
+          message.data.connectionId, message.data.transactionId,
+          message.data.bufferId, message.data.timestampUs, &rhandle, &rbuffer);
+      mManager->close(message.data.connectionId);
+      if (status != ResultStatus::OK) {
+        message.data.command = PipeCommand::RECEIVE_ERROR;
+        sendMessage(mResultPipeFds, message);
+        return;
+      }
+      if (!TestBufferPoolAllocator::Verify(rhandle, 0x77)) {
+        message.data.command = PipeCommand::RECEIVE_ERROR;
+        sendMessage(mResultPipeFds, message);
+        return;
+      }
+      if (rhandle) {
+        native_handle_close(rhandle);
+        native_handle_delete(rhandle);
+      }
+    }
+    message.data.command = PipeCommand::RECEIVE_OK;
+    sendMessage(mResultPipeFds, message);
+  }
+};
+
+// Buffer transfer test between processes.
+TEST_F(BufferpoolMultiTest, TransferBuffer) {
+  ResultStatus status;
+  PipeMessage message;
+
+  ASSERT_TRUE(receiveMessage(mResultPipeFds, &message));
+
+  android::sp<IClientManager> receiver = IClientManager::getService();
+  ConnectionId receiverId;
+  ASSERT_TRUE((bool)receiver);
+
+  status = mManager->registerSender(receiver, mConnectionId, &receiverId);
+  ASSERT_TRUE(status == ResultStatus::OK);
+  {
+    native_handle_t *shandle = nullptr;
+    std::shared_ptr<BufferPoolData> sbuffer;
+    TransactionId transactionId;
+    int64_t postUs;
+    std::vector<uint8_t> vecParams;
+
+    getTestAllocatorParams(&vecParams);
+    status = mManager->allocate(mConnectionId, vecParams, &shandle, &sbuffer);
+    ASSERT_TRUE(status == ResultStatus::OK);
+
+    ASSERT_TRUE(TestBufferPoolAllocator::Fill(shandle, 0x77));
+    if (shandle) {
+        native_handle_close(shandle);
+        native_handle_delete(shandle);
+    }
+
+    status = mManager->postSend(receiverId, sbuffer, &transactionId, &postUs);
+    ASSERT_TRUE(status == ResultStatus::OK);
+
+    message.data.command = PipeCommand::SEND;
+    message.data.bufferId = sbuffer->mId;
+    message.data.connectionId = receiverId;
+    message.data.transactionId = transactionId;
+    message.data.timestampUs = postUs;
+    sendMessage(mCommandPipeFds, message);
+  }
+  EXPECT_TRUE(receiveMessage(mResultPipeFds, &message));
+  EXPECT_TRUE(message.data.command == PipeCommand::RECEIVE_OK);
+}
+
+}  // anonymous namespace
+
+int main(int argc, char** argv) {
+  android::hardware::details::setTrebleTestingOverride(true);
+  ::testing::InitGoogleTest(&argc, argv);
+  int status = RUN_ALL_TESTS();
+  LOG(INFO) << "Test result = " << status;
+  return status;
+}
diff --git a/media/bufferpool/aidl/default/tests/single.cpp b/media/bufferpool/aidl/default/tests/single.cpp
new file mode 100644
index 0000000..1e9027b
--- /dev/null
+++ b/media/bufferpool/aidl/default/tests/single.cpp
@@ -0,0 +1,183 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "buffferpool_unit_test"
+
+#include <gtest/gtest.h>
+
+#include <android-base/logging.h>
+#include <binder/ProcessState.h>
+#include <bufferpool/ClientManager.h>
+#include <hidl/HidlSupport.h>
+#include <hidl/HidlTransportSupport.h>
+#include <hidl/LegacySupport.h>
+#include <hidl/Status.h>
+#include <unistd.h>
+#include <iostream>
+#include <memory>
+#include <vector>
+#include "allocator.h"
+
+using android::hardware::hidl_handle;
+using android::hardware::media::bufferpool::V2_0::ResultStatus;
+using android::hardware::media::bufferpool::V2_0::implementation::BufferId;
+using android::hardware::media::bufferpool::V2_0::implementation::ClientManager;
+using android::hardware::media::bufferpool::V2_0::implementation::ConnectionId;
+using android::hardware::media::bufferpool::V2_0::implementation::TransactionId;
+using android::hardware::media::bufferpool::BufferPoolData;
+
+namespace {
+
+// Number of iteration for buffer allocation test.
+constexpr static int kNumAllocationTest = 3;
+
+// Number of iteration for buffer recycling test.
+constexpr static int kNumRecycleTest = 3;
+
+// media.bufferpool test setup
+class BufferpoolSingleTest : public ::testing::Test {
+ public:
+  virtual void SetUp() override {
+    ResultStatus status;
+    mConnectionValid = false;
+
+    mManager = ClientManager::getInstance();
+    ASSERT_NE(mManager, nullptr);
+
+    mAllocator = std::make_shared<TestBufferPoolAllocator>();
+    ASSERT_TRUE((bool)mAllocator);
+
+    status = mManager->create(mAllocator, &mConnectionId);
+    ASSERT_TRUE(status == ResultStatus::OK);
+
+    mConnectionValid = true;
+
+    status = mManager->registerSender(mManager, mConnectionId, &mReceiverId);
+    ASSERT_TRUE(status == ResultStatus::ALREADY_EXISTS &&
+                mReceiverId == mConnectionId);
+  }
+
+  virtual void TearDown() override {
+    if (mConnectionValid) {
+      mManager->close(mConnectionId);
+    }
+  }
+
+ protected:
+  static void description(const std::string& description) {
+    RecordProperty("description", description);
+  }
+
+  android::sp<ClientManager> mManager;
+  std::shared_ptr<BufferPoolAllocator> mAllocator;
+  bool mConnectionValid;
+  ConnectionId mConnectionId;
+  ConnectionId mReceiverId;
+
+};
+
+// Buffer allocation test.
+// Check whether each buffer allocation is done successfully with
+// unique buffer id.
+TEST_F(BufferpoolSingleTest, AllocateBuffer) {
+  ResultStatus status;
+  std::vector<uint8_t> vecParams;
+  getTestAllocatorParams(&vecParams);
+
+  std::shared_ptr<BufferPoolData> buffer[kNumAllocationTest];
+  native_handle_t *allocHandle = nullptr;
+  for (int i = 0; i < kNumAllocationTest; ++i) {
+    status = mManager->allocate(mConnectionId, vecParams, &allocHandle, &buffer[i]);
+    ASSERT_TRUE(status == ResultStatus::OK);
+    if (allocHandle) {
+      native_handle_close(allocHandle);
+      native_handle_delete(allocHandle);
+    }
+  }
+  for (int i = 0; i < kNumAllocationTest; ++i) {
+    for (int j = i + 1; j < kNumAllocationTest; ++j) {
+      ASSERT_TRUE(buffer[i]->mId != buffer[j]->mId);
+    }
+  }
+  EXPECT_TRUE(kNumAllocationTest > 1);
+}
+
+// Buffer recycle test.
+// Check whether de-allocated buffers are recycled.
+TEST_F(BufferpoolSingleTest, RecycleBuffer) {
+  ResultStatus status;
+  std::vector<uint8_t> vecParams;
+  getTestAllocatorParams(&vecParams);
+
+  BufferId bid[kNumRecycleTest];
+  for (int i = 0; i < kNumRecycleTest; ++i) {
+    std::shared_ptr<BufferPoolData> buffer;
+    native_handle_t *allocHandle = nullptr;
+    status = mManager->allocate(mConnectionId, vecParams, &allocHandle, &buffer);
+    ASSERT_TRUE(status == ResultStatus::OK);
+    bid[i] = buffer->mId;
+    if (allocHandle) {
+      native_handle_close(allocHandle);
+      native_handle_delete(allocHandle);
+    }
+  }
+  for (int i = 1; i < kNumRecycleTest; ++i) {
+    ASSERT_TRUE(bid[i - 1] == bid[i]);
+  }
+  EXPECT_TRUE(kNumRecycleTest > 1);
+}
+
+// Buffer transfer test.
+// Check whether buffer is transferred to another client successfully.
+TEST_F(BufferpoolSingleTest, TransferBuffer) {
+  ResultStatus status;
+  std::vector<uint8_t> vecParams;
+  getTestAllocatorParams(&vecParams);
+  std::shared_ptr<BufferPoolData> sbuffer, rbuffer;
+  native_handle_t *allocHandle = nullptr;
+  native_handle_t *recvHandle = nullptr;
+
+  TransactionId transactionId;
+  int64_t postUs;
+
+  status = mManager->allocate(mConnectionId, vecParams, &allocHandle, &sbuffer);
+  ASSERT_TRUE(status == ResultStatus::OK);
+  ASSERT_TRUE(TestBufferPoolAllocator::Fill(allocHandle, 0x77));
+  status = mManager->postSend(mReceiverId, sbuffer, &transactionId, &postUs);
+  ASSERT_TRUE(status == ResultStatus::OK);
+  status = mManager->receive(mReceiverId, transactionId, sbuffer->mId, postUs,
+                             &recvHandle, &rbuffer);
+  EXPECT_TRUE(status == ResultStatus::OK);
+  ASSERT_TRUE(TestBufferPoolAllocator::Verify(recvHandle, 0x77));
+
+  if (allocHandle) {
+    native_handle_close(allocHandle);
+    native_handle_delete(allocHandle);
+  }
+  if (recvHandle) {
+    native_handle_close(recvHandle);
+    native_handle_delete(recvHandle);
+  }
+}
+
+}  // anonymous namespace
+
+int main(int argc, char** argv) {
+  ::testing::InitGoogleTest(&argc, argv);
+  int status = RUN_ALL_TESTS();
+  LOG(INFO) << "Test result = " << status;
+  return status;
+}