diff --git a/graphics/composer/2.1/default/ComposerClient.cpp b/graphics/composer/2.1/default/ComposerClient.cpp
index d6a1d4d..807ff81 100644
--- a/graphics/composer/2.1/default/ComposerClient.cpp
+++ b/graphics/composer/2.1/default/ComposerClient.cpp
@@ -28,111 +28,6 @@
 namespace V2_1 {
 namespace implementation {
 
-namespace {
-
-using MapperError = android::hardware::graphics::mapper::V2_0::Error;
-using android::hardware::graphics::mapper::V2_0::IMapper;
-
-class HandleImporter {
-public:
-    bool initialize()
-    {
-        // allow only one client
-        if (mInitialized) {
-            return false;
-        }
-
-        mMapper = IMapper::getService();
-
-        mInitialized = true;
-        return true;
-    }
-
-    void cleanup()
-    {
-        mMapper.clear();
-        mInitialized = false;
-    }
-
-    // In IComposer, any buffer_handle_t is owned by the caller and we need to
-    // make a clone for hwcomposer2.  We also need to translate empty handle
-    // to nullptr.  This function does that, in-place.
-    bool importBuffer(buffer_handle_t& handle)
-    {
-        if (!handle) {
-            return true;
-        }
-
-        if (!handle->numFds && !handle->numInts) {
-            handle = nullptr;
-            return true;
-        }
-
-        MapperError error;
-        buffer_handle_t importedHandle;
-        mMapper->importBuffer(
-            hidl_handle(handle),
-            [&](const auto& tmpError, const auto& tmpBufferHandle) {
-                error = tmpError;
-                importedHandle = static_cast<buffer_handle_t>(tmpBufferHandle);
-            });
-        if (error != MapperError::NONE) {
-            return false;
-        }
-
-        handle = importedHandle;
-
-        return true;
-    }
-
-    void freeBuffer(buffer_handle_t handle)
-    {
-        if (!handle) {
-            return;
-        }
-
-        mMapper->freeBuffer(const_cast<native_handle_t*>(handle));
-    }
-
-private:
- bool mInitialized = false;
- sp<IMapper> mMapper;
-};
-
-HandleImporter sHandleImporter;
-
-} // anonymous namespace
-
-BufferCacheEntry::BufferCacheEntry()
-    : mHandle(nullptr)
-{
-}
-
-BufferCacheEntry::BufferCacheEntry(BufferCacheEntry&& other)
-{
-    mHandle = other.mHandle;
-    other.mHandle = nullptr;
-}
-
-BufferCacheEntry& BufferCacheEntry::operator=(buffer_handle_t handle)
-{
-    clear();
-    mHandle = handle;
-    return *this;
-}
-
-BufferCacheEntry::~BufferCacheEntry()
-{
-    clear();
-}
-
-void BufferCacheEntry::clear()
-{
-    if (mHandle) {
-        sHandleImporter.freeBuffer(mHandle);
-    }
-}
-
 ComposerClient::ComposerClient(ComposerHal& hal)
     : mHal(hal), mWriter(kWriterInitialSize)
 {
@@ -140,6 +35,17 @@
 
 ComposerClient::~ComposerClient()
 {
+    ALOGD("destroying composer client");
+
+    mHal.enableCallback(false);
+    destroyResources();
+    mHal.removeClient();
+
+    ALOGD("removed composer client");
+}
+
+void ComposerClient::destroyResources()
+{
     // We want to call hwc2_close here (and move hwc2_open to the
     // constructor), with the assumption that hwc2_close would
     //
@@ -153,21 +59,15 @@
     //
     // Below we manually clean all resources (layers and virtual
     // displays), and perform a presentDisplay afterwards.
-    ALOGW("destroying composer client");
+    mResources->clear([this](Display display, bool isVirtual, const std::vector<Layer> layers) {
+        ALOGW("destroying client resources for display %" PRIu64, display);
 
-    mHal.enableCallback(false);
-
-    // no need to grab the mutex as any in-flight hwbinder call would have
-    // kept the client alive
-    for (const auto& dpy : mDisplayData) {
-        ALOGW("destroying client resources for display %" PRIu64, dpy.first);
-
-        for (const auto& ly : dpy.second.Layers) {
-            mHal.destroyLayer(dpy.first, ly.first);
+        for (auto layer : layers) {
+            mHal.destroyLayer(display, layer);
         }
 
-        if (dpy.second.IsVirtual) {
-            mHal.destroyVirtualDisplay(dpy.first);
+        if (isVirtual) {
+            mHal.destroyVirtualDisplay(display);
         } else {
             ALOGW("performing a final presentDisplay");
 
@@ -176,15 +76,15 @@
             uint32_t displayRequestMask = 0;
             std::vector<Layer> requestedLayers;
             std::vector<uint32_t> requestMasks;
-            mHal.validateDisplay(dpy.first, &changedLayers, &compositionTypes,
-                    &displayRequestMask, &requestedLayers, &requestMasks);
+            mHal.validateDisplay(display, &changedLayers, &compositionTypes, &displayRequestMask,
+                                 &requestedLayers, &requestMasks);
 
-            mHal.acceptDisplayChanges(dpy.first);
+            mHal.acceptDisplayChanges(display);
 
             int32_t presentFence = -1;
             std::vector<Layer> releasedLayers;
             std::vector<int32_t> releaseFences;
-            mHal.presentDisplay(dpy.first, &presentFence, &releasedLayers, &releaseFences);
+            mHal.presentDisplay(display, &presentFence, &releasedLayers, &releaseFences);
             if (presentFence >= 0) {
                 close(presentFence);
             }
@@ -194,36 +94,28 @@
                 }
             }
         }
-    }
+    });
 
-    mDisplayData.clear();
-
-    sHandleImporter.cleanup();
-
-    mHal.removeClient();
-
-    ALOGW("removed composer client");
+    mResources.reset();
 }
 
 void ComposerClient::initialize()
 {
-    mReader = createCommandReader();
-    if (!sHandleImporter.initialize()) {
-        LOG_ALWAYS_FATAL("failed to initialize handle importer");
+    mResources = createResources();
+    if (!mResources) {
+        LOG_ALWAYS_FATAL("failed to create resources");
     }
+
+    mReader = createCommandReader();
 }
 
 void ComposerClient::onHotplug(Display display,
         IComposerCallback::Connection connected)
 {
-    {
-        std::lock_guard<std::mutex> lock(mDisplayDataMutex);
-
-        if (connected == IComposerCallback::Connection::CONNECTED) {
-            mDisplayData.emplace(display, DisplayData(false));
-        } else if (connected == IComposerCallback::Connection::DISCONNECTED) {
-            mDisplayData.erase(display);
-        }
+    if (connected == IComposerCallback::Connection::CONNECTED) {
+        mResources->addPhysicalDisplay(display);
+    } else if (connected == IComposerCallback::Connection::DISCONNECTED) {
+        mResources->removeDisplay(display);
     }
 
     auto ret = mCallback->onHotplug(display, connected);
@@ -268,10 +160,7 @@
     Error err = mHal.createVirtualDisplay(width, height,
             &formatHint, &display);
     if (err == Error::NONE) {
-        std::lock_guard<std::mutex> lock(mDisplayDataMutex);
-
-        auto dpy = mDisplayData.emplace(display, DisplayData(true)).first;
-        dpy->second.OutputBuffers.resize(outputBufferSlotCount);
+        mResources->addVirtualDisplay(display, outputBufferSlotCount);
     }
 
     hidl_cb(err, display, formatHint);
@@ -282,9 +171,7 @@
 {
     Error err = mHal.destroyVirtualDisplay(display);
     if (err == Error::NONE) {
-        std::lock_guard<std::mutex> lock(mDisplayDataMutex);
-
-        mDisplayData.erase(display);
+        mResources->removeDisplay(display);
     }
 
     return err;
@@ -296,14 +183,9 @@
     Layer layer = 0;
     Error err = mHal.createLayer(display, &layer);
     if (err == Error::NONE) {
-        std::lock_guard<std::mutex> lock(mDisplayDataMutex);
-        auto dpy = mDisplayData.find(display);
-        // The display entry may have already been removed by onHotplug.
-        if (dpy != mDisplayData.end()) {
-            auto ly = dpy->second.Layers.emplace(layer, LayerBuffers()).first;
-            ly->second.Buffers.resize(bufferSlotCount);
-        } else {
-            err = Error::BAD_DISPLAY;
+        err = mResources->addLayer(display, layer, bufferSlotCount);
+        if (err != Error::NONE) {
+            // The display entry may have already been removed by onHotplug.
             // Note: We do not destroy the layer on this error as the hotplug
             // disconnect invalidates the display id. The implementation should
             // ensure all layers for the display are destroyed.
@@ -318,13 +200,7 @@
 {
     Error err = mHal.destroyLayer(display, layer);
     if (err == Error::NONE) {
-        std::lock_guard<std::mutex> lock(mDisplayDataMutex);
-
-        auto dpy = mDisplayData.find(display);
-        // The display entry may have already been removed by onHotplug.
-        if (dpy != mDisplayData.end()) {
-            dpy->second.Layers.erase(layer);
-        }
+        mResources->removeLayer(display, layer);
     }
 
     return err;
@@ -427,16 +303,7 @@
 Return<Error> ComposerClient::setClientTargetSlotCount(Display display,
         uint32_t clientTargetSlotCount)
 {
-    std::lock_guard<std::mutex> lock(mDisplayDataMutex);
-
-    auto dpy = mDisplayData.find(display);
-    if (dpy == mDisplayData.end()) {
-        return Error::BAD_DISPLAY;
-    }
-
-    dpy->second.ClientTargets.resize(clientTargetSlotCount);
-
-    return Error::NONE;
+    return mResources->setDisplayClientTargetCacheSize(display, clientTargetSlotCount);
 }
 
 Return<Error> ComposerClient::setActiveConfig(Display display, Config config)
@@ -516,6 +383,11 @@
     return Void();
 }
 
+std::unique_ptr<ComposerResources> ComposerClient::createResources()
+{
+    return ComposerResources::create();
+}
+
 std::unique_ptr<ComposerClient::CommandReader>
 ComposerClient::createCommandReader()
 {
@@ -524,7 +396,7 @@
 }
 
 ComposerClient::CommandReader::CommandReader(ComposerClient& client)
-    : mClient(client), mHal(client.mHal), mWriter(client.mWriter)
+    : mHal(client.mHal), mResources(client.mResources.get()), mWriter(client.mWriter)
 {
 }
 
@@ -661,22 +533,21 @@
 
     bool useCache = false;
     auto slot = read();
-    auto clientTarget = readHandle(&useCache);
+    auto rawHandle = readHandle(&useCache);
     auto fence = readFence();
     auto dataspace = readSigned();
     auto damage = readRegion((length - 4) / 4);
     bool closeFence = true;
 
-    auto err = lookupBuffer(BufferCache::CLIENT_TARGETS,
-            slot, useCache, clientTarget, &clientTarget);
+    const native_handle_t* clientTarget;
+    ComposerResources::ReplacedBufferHandle replacedClientTarget;
+    auto err = mResources->getDisplayClientTarget(mDisplay,
+            slot, useCache, rawHandle, &clientTarget, &replacedClientTarget);
     if (err == Error::NONE) {
         err = mHal.setClientTarget(mDisplay, clientTarget, fence,
                 dataspace, damage);
-        auto updateBufErr = updateBuffer(BufferCache::CLIENT_TARGETS, slot,
-                useCache, clientTarget);
         if (err == Error::NONE) {
             closeFence = false;
-            err = updateBufErr;
         }
     }
     if (closeFence) {
@@ -697,19 +568,18 @@
 
     bool useCache = false;
     auto slot = read();
-    auto outputBuffer = readHandle(&useCache);
+    auto rawhandle = readHandle(&useCache);
     auto fence = readFence();
     bool closeFence = true;
 
-    auto err = lookupBuffer(BufferCache::OUTPUT_BUFFERS,
-            slot, useCache, outputBuffer, &outputBuffer);
+    const native_handle_t* outputBuffer;
+    ComposerResources::ReplacedBufferHandle replacedOutputBuffer;
+    auto err = mResources->getDisplayOutputBuffer(mDisplay,
+            slot, useCache, rawhandle, &outputBuffer, &replacedOutputBuffer);
     if (err == Error::NONE) {
         err = mHal.setOutputBuffer(mDisplay, outputBuffer, fence);
-        auto updateBufErr = updateBuffer(BufferCache::OUTPUT_BUFFERS,
-                slot, useCache, outputBuffer);
         if (err == Error::NONE) {
             closeFence = false;
-            err = updateBufErr;
         }
     }
     if (closeFence) {
@@ -848,19 +718,18 @@
 
     bool useCache = false;
     auto slot = read();
-    auto buffer = readHandle(&useCache);
+    auto rawHandle = readHandle(&useCache);
     auto fence = readFence();
     bool closeFence = true;
 
-    auto err = lookupBuffer(BufferCache::LAYER_BUFFERS,
-            slot, useCache, buffer, &buffer);
+    const native_handle_t* buffer;
+    ComposerResources::ReplacedBufferHandle replacedBuffer;
+    auto err = mResources->getLayerBuffer(mDisplay, mLayer,
+            slot, useCache, rawHandle, &buffer, &replacedBuffer);
     if (err == Error::NONE) {
         err = mHal.setLayerBuffer(mDisplay, mLayer, buffer, fence);
-        auto updateBufErr = updateBuffer(BufferCache::LAYER_BUFFERS, slot,
-                useCache, buffer);
         if (err == Error::NONE) {
             closeFence = false;
-            err = updateBufErr;
         }
     }
     if (closeFence) {
@@ -980,15 +849,14 @@
         return false;
     }
 
-    auto stream = readHandle();
+    auto rawHandle = readHandle();
 
-    auto err = lookupLayerSidebandStream(stream, &stream);
+    const native_handle_t* stream;
+    ComposerResources::ReplacedStreamHandle replacedStream;
+    auto err = mResources->getLayerSidebandStream(mDisplay, mLayer,
+            rawHandle, &stream, &replacedStream);
     if (err == Error::NONE) {
         err = mHal.setLayerSidebandStream(mDisplay, mLayer, stream);
-        auto updateErr = updateLayerSidebandStream(stream);
-        if (err == Error::NONE) {
-            err = updateErr;
-        }
     }
     if (err != Error::NONE) {
         mWriter.setError(getCommandLoc(), err);
@@ -1087,115 +955,6 @@
     };
 }
 
-Error ComposerClient::CommandReader::lookupBufferCacheEntryLocked(
-        BufferCache cache, uint32_t slot, BufferCacheEntry** outEntry)
-{
-    auto dpy = mClient.mDisplayData.find(mDisplay);
-    if (dpy == mClient.mDisplayData.end()) {
-        return Error::BAD_DISPLAY;
-    }
-
-    BufferCacheEntry* entry = nullptr;
-    switch (cache) {
-    case BufferCache::CLIENT_TARGETS:
-        if (slot < dpy->second.ClientTargets.size()) {
-            entry = &dpy->second.ClientTargets[slot];
-        }
-        break;
-    case BufferCache::OUTPUT_BUFFERS:
-        if (slot < dpy->second.OutputBuffers.size()) {
-            entry = &dpy->second.OutputBuffers[slot];
-        }
-        break;
-    case BufferCache::LAYER_BUFFERS:
-        {
-            auto ly = dpy->second.Layers.find(mLayer);
-            if (ly == dpy->second.Layers.end()) {
-                return Error::BAD_LAYER;
-            }
-            if (slot < ly->second.Buffers.size()) {
-                entry = &ly->second.Buffers[slot];
-            }
-        }
-        break;
-    case BufferCache::LAYER_SIDEBAND_STREAMS:
-        {
-            auto ly = dpy->second.Layers.find(mLayer);
-            if (ly == dpy->second.Layers.end()) {
-                return Error::BAD_LAYER;
-            }
-            if (slot == 0) {
-                entry = &ly->second.SidebandStream;
-            }
-        }
-        break;
-    default:
-        break;
-    }
-
-    if (!entry) {
-        ALOGW("invalid buffer slot %" PRIu32, slot);
-        return Error::BAD_PARAMETER;
-    }
-
-    *outEntry = entry;
-
-    return Error::NONE;
-}
-
-Error ComposerClient::CommandReader::lookupBuffer(BufferCache cache,
-        uint32_t slot, bool useCache, buffer_handle_t handle,
-        buffer_handle_t* outHandle)
-{
-    if (useCache) {
-        std::lock_guard<std::mutex> lock(mClient.mDisplayDataMutex);
-
-        BufferCacheEntry* entry;
-        Error error = lookupBufferCacheEntryLocked(cache, slot, &entry);
-        if (error != Error::NONE) {
-            return error;
-        }
-
-        // input handle is ignored
-        *outHandle = entry->getHandle();
-    } else if (cache == BufferCache::LAYER_SIDEBAND_STREAMS) {
-        if (handle) {
-            *outHandle = native_handle_clone(handle);
-            if (*outHandle == nullptr) {
-                return Error::NO_RESOURCES;
-            }
-        }
-    } else {
-        if (!sHandleImporter.importBuffer(handle)) {
-            return Error::NO_RESOURCES;
-        }
-
-        *outHandle = handle;
-    }
-
-    return Error::NONE;
-}
-
-Error ComposerClient::CommandReader::updateBuffer(BufferCache cache,
-        uint32_t slot, bool useCache, buffer_handle_t handle)
-{
-    // handle was looked up from cache
-    if (useCache) {
-        return Error::NONE;
-    }
-
-    std::lock_guard<std::mutex> lock(mClient.mDisplayDataMutex);
-
-    BufferCacheEntry* entry = nullptr;
-    Error error = lookupBufferCacheEntryLocked(cache, slot, &entry);
-    if (error != Error::NONE) {
-      return error;
-    }
-
-    *entry = handle;
-    return Error::NONE;
-}
-
 } // namespace implementation
 } // namespace V2_1
 } // namespace composer
diff --git a/graphics/composer/2.1/default/ComposerClient.h b/graphics/composer/2.1/default/ComposerClient.h
index 9664cbe..ee71492 100644
--- a/graphics/composer/2.1/default/ComposerClient.h
+++ b/graphics/composer/2.1/default/ComposerClient.h
@@ -23,6 +23,7 @@
 
 #include <composer-command-buffer/2.1/ComposerCommandBuffer.h>
 #include <composer-hal/2.1/ComposerHal.h>
+#include <composer-hal/2.1/ComposerResources.h>
 #include <hardware/hwcomposer2.h>
 
 namespace android {
@@ -34,25 +35,6 @@
 
 using namespace hal;
 
-class BufferCacheEntry {
-public:
-    BufferCacheEntry();
-    BufferCacheEntry(BufferCacheEntry&& other);
-
-    BufferCacheEntry(const BufferCacheEntry& other) = delete;
-    BufferCacheEntry& operator=(const BufferCacheEntry& other) = delete;
-
-    BufferCacheEntry& operator=(buffer_handle_t handle);
-    ~BufferCacheEntry();
-
-    buffer_handle_t getHandle() const { return mHandle; }
-
-private:
-    void clear();
-
-    buffer_handle_t mHandle;
-};
-
 class ComposerClient : public IComposerClient {
 public:
     ComposerClient(ComposerHal& hal);
@@ -110,23 +92,6 @@
             executeCommands_cb hidl_cb) override;
 
 protected:
-    struct LayerBuffers {
-        std::vector<BufferCacheEntry> Buffers;
-        // the handle is a sideband stream handle, not a buffer handle
-        BufferCacheEntry SidebandStream;
-    };
-
-    struct DisplayData {
-        bool IsVirtual;
-
-        std::vector<BufferCacheEntry> ClientTargets;
-        std::vector<BufferCacheEntry> OutputBuffers;
-
-        std::unordered_map<Layer, LayerBuffers> Layers;
-
-        DisplayData(bool isVirtual) : IsVirtual(isVirtual) {}
-    };
-
     class CommandReader : public CommandReaderBase {
     public:
         CommandReader(ComposerClient& client);
@@ -166,44 +131,23 @@
         std::vector<hwc_rect_t> readRegion(size_t count);
         hwc_frect_t readFRect();
 
-        enum class BufferCache {
-            CLIENT_TARGETS,
-            OUTPUT_BUFFERS,
-            LAYER_BUFFERS,
-            LAYER_SIDEBAND_STREAMS,
-        };
-        Error lookupBufferCacheEntryLocked(BufferCache cache, uint32_t slot,
-                BufferCacheEntry** outEntry);
-        Error lookupBuffer(BufferCache cache, uint32_t slot,
-                bool useCache, buffer_handle_t handle,
-                buffer_handle_t* outHandle);
-        Error updateBuffer(BufferCache cache, uint32_t slot,
-                bool useCache, buffer_handle_t handle);
-
-        Error lookupLayerSidebandStream(buffer_handle_t handle,
-                buffer_handle_t* outHandle)
-        {
-            return lookupBuffer(BufferCache::LAYER_SIDEBAND_STREAMS,
-                    0, false, handle, outHandle);
-        }
-        Error updateLayerSidebandStream(buffer_handle_t handle)
-        {
-            return updateBuffer(BufferCache::LAYER_SIDEBAND_STREAMS,
-                    0, false, handle);
-        }
-
-        ComposerClient& mClient;
         ComposerHal& mHal;
+        ComposerResources* mResources;
         CommandWriterBase& mWriter;
 
         Display mDisplay;
         Layer mLayer;
     };
 
+    void destroyResources();
+
+    virtual std::unique_ptr<ComposerResources> createResources();
     virtual std::unique_ptr<CommandReader> createCommandReader();
 
     ComposerHal& mHal;
 
+    std::unique_ptr<ComposerResources> mResources;
+
     // 64KiB minus a small space for metadata such as read/write pointers
     static constexpr size_t kWriterInitialSize =
         64 * 1024 / sizeof(uint32_t) - 16;
@@ -212,9 +156,6 @@
     CommandWriterBase mWriter;
 
     sp<IComposerCallback> mCallback;
-
-    std::mutex mDisplayDataMutex;
-    std::unordered_map<Display, DisplayData> mDisplayData;
 };
 
 } // namespace implementation
diff --git a/graphics/composer/2.1/utils/hal/Android.bp b/graphics/composer/2.1/utils/hal/Android.bp
index 35ddc0a..a8ff59d 100644
--- a/graphics/composer/2.1/utils/hal/Android.bp
+++ b/graphics/composer/2.1/utils/hal/Android.bp
@@ -19,10 +19,12 @@
     vendor_available: true,
     shared_libs: [
         "android.hardware.graphics.composer@2.1",
+        "android.hardware.graphics.mapper@2.0",
         "libhardware", // TODO remove hwcomposer2.h dependency
     ],
     export_shared_lib_headers: [
         "android.hardware.graphics.composer@2.1",
+        "android.hardware.graphics.mapper@2.0",
         "libhardware",
     ],
     export_include_dirs: ["include"],
diff --git a/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerResources.h b/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerResources.h
new file mode 100644
index 0000000..7bb3692
--- /dev/null
+++ b/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerResources.h
@@ -0,0 +1,536 @@
+/*
+ * Copyright 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.
+ */
+
+#pragma once
+
+#ifndef LOG_TAG
+#warning "ComposerResources.h included without LOG_TAG"
+#endif
+
+#include <memory>
+#include <mutex>
+#include <unordered_map>
+#include <vector>
+
+#include <android/hardware/graphics/mapper/2.0/IMapper.h>
+#include <log/log.h>
+
+namespace android {
+namespace hardware {
+namespace graphics {
+namespace composer {
+namespace V2_1 {
+namespace hal {
+
+// wrapper for IMapper to import buffers and sideband streams
+class ComposerHandleImporter {
+   public:
+    bool init() {
+        mMapper = mapper::V2_0::IMapper::getService();
+        ALOGE_IF(!mMapper, "failed to get mapper service");
+        return mMapper != nullptr;
+    }
+
+    Error importBuffer(const native_handle_t* rawHandle, const native_handle_t** outBufferHandle) {
+        if (!rawHandle || (!rawHandle->numFds && !rawHandle->numInts)) {
+            *outBufferHandle = nullptr;
+            return Error::NONE;
+        }
+
+        mapper::V2_0::Error error;
+        const native_handle_t* bufferHandle;
+        mMapper->importBuffer(rawHandle, [&](const auto& tmpError, const auto& tmpBufferHandle) {
+            error = tmpError;
+            bufferHandle = static_cast<const native_handle_t*>(tmpBufferHandle);
+        });
+        if (error != mapper::V2_0::Error::NONE) {
+            return Error::NO_RESOURCES;
+        }
+
+        *outBufferHandle = bufferHandle;
+        return Error::NONE;
+    }
+
+    void freeBuffer(const native_handle_t* bufferHandle) {
+        if (bufferHandle) {
+            mMapper->freeBuffer(static_cast<void*>(const_cast<native_handle_t*>(bufferHandle)));
+        }
+    }
+
+    Error importStream(const native_handle_t* rawHandle, const native_handle_t** outStreamHandle) {
+        const native_handle_t* streamHandle = nullptr;
+        if (rawHandle) {
+            streamHandle = native_handle_clone(rawHandle);
+            if (!streamHandle) {
+                return Error::NO_RESOURCES;
+            }
+        }
+
+        *outStreamHandle = streamHandle;
+        return Error::NONE;
+    }
+
+    void freeStream(const native_handle_t* streamHandle) {
+        if (streamHandle) {
+            native_handle_close(streamHandle);
+            native_handle_delete(const_cast<native_handle_t*>(streamHandle));
+        }
+    }
+
+   private:
+    sp<mapper::V2_0::IMapper> mMapper;
+};
+
+class ComposerHandleCache {
+   public:
+    enum class HandleType {
+        INVALID,
+        BUFFER,
+        STREAM,
+    };
+
+    ComposerHandleCache(ComposerHandleImporter& importer, HandleType type, uint32_t cacheSize)
+        : mImporter(importer), mHandleType(type), mHandles(cacheSize, nullptr) {}
+
+    // must be initialized later with initCache
+    ComposerHandleCache(ComposerHandleImporter& importer) : mImporter(importer) {}
+
+    ~ComposerHandleCache() {
+        switch (mHandleType) {
+            case HandleType::BUFFER:
+                for (auto handle : mHandles) {
+                    mImporter.freeBuffer(handle);
+                }
+                break;
+            case HandleType::STREAM:
+                for (auto handle : mHandles) {
+                    mImporter.freeStream(handle);
+                }
+                break;
+            default:
+                break;
+        }
+    }
+
+    ComposerHandleCache(const ComposerHandleCache&) = delete;
+    ComposerHandleCache& operator=(const ComposerHandleCache&) = delete;
+
+    bool initCache(HandleType type, uint32_t cacheSize) {
+        // already initialized
+        if (mHandleType != HandleType::INVALID) {
+            return false;
+        }
+
+        mHandleType = type;
+        mHandles.resize(cacheSize, nullptr);
+
+        return true;
+    }
+
+    Error lookupCache(uint32_t slot, const native_handle_t** outHandle) {
+        if (slot < mHandles.size()) {
+            *outHandle = mHandles[slot];
+            return Error::NONE;
+        } else {
+            return Error::BAD_PARAMETER;
+        }
+    }
+
+    Error updateCache(uint32_t slot, const native_handle_t* handle,
+                      const native_handle** outReplacedHandle) {
+        if (slot < mHandles.size()) {
+            auto& cachedHandle = mHandles[slot];
+            *outReplacedHandle = cachedHandle;
+            cachedHandle = handle;
+            return Error::NONE;
+        } else {
+            return Error::BAD_PARAMETER;
+        }
+    }
+
+    // when fromCache is true, look up in the cache; otherwise, update the cache
+    Error getHandle(uint32_t slot, bool fromCache, const native_handle_t* inHandle,
+                    const native_handle_t** outHandle, const native_handle** outReplacedHandle) {
+        if (fromCache) {
+            *outReplacedHandle = nullptr;
+            return lookupCache(slot, outHandle);
+        } else {
+            *outHandle = inHandle;
+            return updateCache(slot, inHandle, outReplacedHandle);
+        }
+    }
+
+   private:
+    ComposerHandleImporter& mImporter;
+    HandleType mHandleType = HandleType::INVALID;
+    std::vector<const native_handle_t*> mHandles;
+};
+
+// layer resource
+class ComposerLayerResource {
+   public:
+    ComposerLayerResource(ComposerHandleImporter& importer, uint32_t bufferCacheSize)
+        : mBufferCache(importer, ComposerHandleCache::HandleType::BUFFER, bufferCacheSize),
+          mSidebandStreamCache(importer, ComposerHandleCache::HandleType::STREAM, 1) {}
+
+    Error getBuffer(uint32_t slot, bool fromCache, const native_handle_t* inHandle,
+                    const native_handle_t** outHandle, const native_handle** outReplacedHandle) {
+        return mBufferCache.getHandle(slot, fromCache, inHandle, outHandle, outReplacedHandle);
+    }
+
+    Error getSidebandStream(uint32_t slot, bool fromCache, const native_handle_t* inHandle,
+                            const native_handle_t** outHandle,
+                            const native_handle** outReplacedHandle) {
+        return mSidebandStreamCache.getHandle(slot, fromCache, inHandle, outHandle,
+                                              outReplacedHandle);
+    }
+
+   protected:
+    ComposerHandleCache mBufferCache;
+    ComposerHandleCache mSidebandStreamCache;
+};
+
+// display resource
+class ComposerDisplayResource {
+   public:
+    enum class DisplayType {
+        PHYSICAL,
+        VIRTUAL,
+    };
+
+    ComposerDisplayResource(DisplayType type, ComposerHandleImporter& importer,
+                            uint32_t outputBufferCacheSize)
+        : mType(type),
+          mClientTargetCache(importer),
+          mOutputBufferCache(importer, ComposerHandleCache::HandleType::BUFFER,
+                             outputBufferCacheSize) {}
+
+    bool initClientTargetCache(uint32_t cacheSize) {
+        return mClientTargetCache.initCache(ComposerHandleCache::HandleType::BUFFER, cacheSize);
+    }
+
+    bool isVirtual() const { return mType == DisplayType::VIRTUAL; }
+
+    Error getClientTarget(uint32_t slot, bool fromCache, const native_handle_t* inHandle,
+                          const native_handle_t** outHandle,
+                          const native_handle** outReplacedHandle) {
+        return mClientTargetCache.getHandle(slot, fromCache, inHandle, outHandle,
+                                            outReplacedHandle);
+    }
+
+    Error getOutputBuffer(uint32_t slot, bool fromCache, const native_handle_t* inHandle,
+                          const native_handle_t** outHandle,
+                          const native_handle** outReplacedHandle) {
+        return mOutputBufferCache.getHandle(slot, fromCache, inHandle, outHandle,
+                                            outReplacedHandle);
+    }
+
+    bool addLayer(Layer layer, std::unique_ptr<ComposerLayerResource> layerResource) {
+        auto result = mLayerResources.emplace(layer, std::move(layerResource));
+        return result.second;
+    }
+
+    bool removeLayer(Layer layer) { return mLayerResources.erase(layer) > 0; }
+
+    ComposerLayerResource* findLayerResource(Layer layer) {
+        auto layerIter = mLayerResources.find(layer);
+        if (layerIter == mLayerResources.end()) {
+            return nullptr;
+        }
+
+        return layerIter->second.get();
+    }
+
+    std::vector<Layer> getLayers() const {
+        std::vector<Layer> layers;
+        layers.reserve(mLayerResources.size());
+        for (const auto& layerKey : mLayerResources) {
+            layers.push_back(layerKey.first);
+        }
+        return layers;
+    }
+
+   protected:
+    const DisplayType mType;
+    ComposerHandleCache mClientTargetCache;
+    ComposerHandleCache mOutputBufferCache;
+
+    std::unordered_map<Layer, std::unique_ptr<ComposerLayerResource>> mLayerResources;
+};
+
+class ComposerResources {
+   private:
+    template <bool isBuffer>
+    class ReplacedHandle;
+
+   public:
+    static std::unique_ptr<ComposerResources> create() {
+        auto resources = std::make_unique<ComposerResources>();
+        return resources->init() ? std::move(resources) : nullptr;
+    }
+
+    ComposerResources() = default;
+    virtual ~ComposerResources() = default;
+
+    bool init() { return mImporter.init(); }
+
+    using RemoveDisplay =
+        std::function<void(Display display, bool isVirtual, const std::vector<Layer>& layers)>;
+    void clear(RemoveDisplay removeDisplay) {
+        std::lock_guard<std::mutex> lock(mDisplayResourcesMutex);
+        for (const auto& displayKey : mDisplayResources) {
+            Display display = displayKey.first;
+            const ComposerDisplayResource& displayResource = *displayKey.second;
+            removeDisplay(display, displayResource.isVirtual(), displayResource.getLayers());
+        }
+        mDisplayResources.clear();
+    }
+
+    Error addPhysicalDisplay(Display display) {
+        auto displayResource =
+            createDisplayResource(ComposerDisplayResource::DisplayType::PHYSICAL, 0);
+
+        std::lock_guard<std::mutex> lock(mDisplayResourcesMutex);
+        auto result = mDisplayResources.emplace(display, std::move(displayResource));
+        return result.second ? Error::NONE : Error::BAD_DISPLAY;
+    }
+
+    Error addVirtualDisplay(Display display, uint32_t outputBufferCacheSize) {
+        auto displayResource = createDisplayResource(ComposerDisplayResource::DisplayType::VIRTUAL,
+                                                     outputBufferCacheSize);
+
+        std::lock_guard<std::mutex> lock(mDisplayResourcesMutex);
+        auto result = mDisplayResources.emplace(display, std::move(displayResource));
+        return result.second ? Error::NONE : Error::BAD_DISPLAY;
+    }
+
+    Error removeDisplay(Display display) {
+        std::lock_guard<std::mutex> lock(mDisplayResourcesMutex);
+        return mDisplayResources.erase(display) > 0 ? Error::NONE : Error::BAD_DISPLAY;
+    }
+
+    Error setDisplayClientTargetCacheSize(Display display, uint32_t clientTargetCacheSize) {
+        std::lock_guard<std::mutex> lock(mDisplayResourcesMutex);
+        ComposerDisplayResource* displayResource = findDisplayResourceLocked(display);
+        if (!displayResource) {
+            return Error::BAD_DISPLAY;
+        }
+
+        return displayResource->initClientTargetCache(clientTargetCacheSize) ? Error::NONE
+                                                                             : Error::BAD_PARAMETER;
+    }
+
+    Error addLayer(Display display, Layer layer, uint32_t bufferCacheSize) {
+        auto layerResource = createLayerResource(bufferCacheSize);
+
+        std::lock_guard<std::mutex> lock(mDisplayResourcesMutex);
+        ComposerDisplayResource* displayResource = findDisplayResourceLocked(display);
+        if (!displayResource) {
+            return Error::BAD_DISPLAY;
+        }
+
+        return displayResource->addLayer(layer, std::move(layerResource)) ? Error::NONE
+                                                                          : Error::BAD_LAYER;
+    }
+
+    Error removeLayer(Display display, Layer layer) {
+        std::lock_guard<std::mutex> lock(mDisplayResourcesMutex);
+        ComposerDisplayResource* displayResource = findDisplayResourceLocked(display);
+        if (!displayResource) {
+            return Error::BAD_DISPLAY;
+        }
+
+        return displayResource->removeLayer(layer) ? Error::NONE : Error::BAD_LAYER;
+    }
+
+    using ReplacedBufferHandle = ReplacedHandle<true>;
+    using ReplacedStreamHandle = ReplacedHandle<false>;
+
+    Error getDisplayClientTarget(Display display, uint32_t slot, bool fromCache,
+                                 const native_handle_t* rawHandle,
+                                 const native_handle_t** outBufferHandle,
+                                 ReplacedBufferHandle* outReplacedBuffer) {
+        return getHandle<Cache::CLIENT_TARGET>(display, 0, slot, fromCache, rawHandle,
+                                               outBufferHandle, outReplacedBuffer);
+    }
+
+    Error getDisplayOutputBuffer(Display display, uint32_t slot, bool fromCache,
+                                 const native_handle_t* rawHandle,
+                                 const native_handle_t** outBufferHandle,
+                                 ReplacedBufferHandle* outReplacedBuffer) {
+        return getHandle<Cache::OUTPUT_BUFFER>(display, 0, slot, fromCache, rawHandle,
+                                               outBufferHandle, outReplacedBuffer);
+    }
+
+    Error getLayerBuffer(Display display, Layer layer, uint32_t slot, bool fromCache,
+                         const native_handle_t* rawHandle, const native_handle_t** outBufferHandle,
+                         ReplacedBufferHandle* outReplacedBuffer) {
+        return getHandle<Cache::LAYER_BUFFER>(display, layer, slot, fromCache, rawHandle,
+                                              outBufferHandle, outReplacedBuffer);
+    }
+
+    Error getLayerSidebandStream(Display display, Layer layer, const native_handle_t* rawHandle,
+                                 const native_handle_t** outStreamHandle,
+                                 ReplacedStreamHandle* outReplacedStream) {
+        return getHandle<Cache::LAYER_SIDEBAND_STREAM>(display, layer, 0, false, rawHandle,
+                                                       outStreamHandle, outReplacedStream);
+    }
+
+   protected:
+    virtual std::unique_ptr<ComposerDisplayResource> createDisplayResource(
+        ComposerDisplayResource::DisplayType type, uint32_t outputBufferCacheSize) {
+        return std::make_unique<ComposerDisplayResource>(type, mImporter, outputBufferCacheSize);
+    }
+
+    virtual std::unique_ptr<ComposerLayerResource> createLayerResource(uint32_t bufferCacheSize) {
+        return std::make_unique<ComposerLayerResource>(mImporter, bufferCacheSize);
+    }
+
+    ComposerDisplayResource* findDisplayResourceLocked(Display display) {
+        auto iter = mDisplayResources.find(display);
+        if (iter == mDisplayResources.end()) {
+            return nullptr;
+        }
+        return iter->second.get();
+    }
+
+    ComposerHandleImporter mImporter;
+
+    std::mutex mDisplayResourcesMutex;
+    std::unordered_map<Display, std::unique_ptr<ComposerDisplayResource>> mDisplayResources;
+
+   private:
+    enum class Cache {
+        CLIENT_TARGET,
+        OUTPUT_BUFFER,
+        LAYER_BUFFER,
+        LAYER_SIDEBAND_STREAM,
+    };
+
+    // When a buffer in the cache is replaced by a new one, we must keep it
+    // alive until it has been replaced in ComposerHal.
+    template <bool isBuffer>
+    class ReplacedHandle {
+       public:
+        ReplacedHandle() = default;
+        ReplacedHandle(const ReplacedHandle&) = delete;
+        ReplacedHandle& operator=(const ReplacedHandle&) = delete;
+
+        ~ReplacedHandle() { reset(); }
+
+        void reset(ComposerHandleImporter* importer = nullptr,
+                   const native_handle_t* handle = nullptr) {
+            if (mHandle) {
+                if (isBuffer) {
+                    mImporter->freeBuffer(mHandle);
+                } else {
+                    mImporter->freeStream(mHandle);
+                }
+            }
+
+            mImporter = importer;
+            mHandle = handle;
+        }
+
+       private:
+        ComposerHandleImporter* mImporter = nullptr;
+        const native_handle_t* mHandle = nullptr;
+    };
+
+    template <Cache cache, bool isBuffer>
+    Error getHandle(Display display, Layer layer, uint32_t slot, bool fromCache,
+                    const native_handle_t* rawHandle, const native_handle_t** outHandle,
+                    ReplacedHandle<isBuffer>* outReplacedHandle) {
+        Error error;
+
+        // import the raw handle (or ignore raw handle when fromCache is true)
+        const native_handle_t* importedHandle = nullptr;
+        if (!fromCache) {
+            error = (isBuffer) ? mImporter.importBuffer(rawHandle, &importedHandle)
+                               : mImporter.importStream(rawHandle, &importedHandle);
+            if (error != Error::NONE) {
+                return error;
+            }
+        }
+
+        std::lock_guard<std::mutex> lock(mDisplayResourcesMutex);
+
+        // find display/layer resource
+        const bool needLayerResource =
+            (cache == Cache::LAYER_BUFFER || cache == Cache::LAYER_SIDEBAND_STREAM);
+        ComposerDisplayResource* displayResource = findDisplayResourceLocked(display);
+        ComposerLayerResource* layerResource = (displayResource && needLayerResource)
+                                                   ? displayResource->findLayerResource(layer)
+                                                   : nullptr;
+
+        // lookup or update cache
+        const native_handle_t* replacedHandle = nullptr;
+        if (displayResource && (!needLayerResource || layerResource)) {
+            switch (cache) {
+                case Cache::CLIENT_TARGET:
+                    error = displayResource->getClientTarget(slot, fromCache, importedHandle,
+                                                             outHandle, &replacedHandle);
+                    break;
+                case Cache::OUTPUT_BUFFER:
+                    error = displayResource->getOutputBuffer(slot, fromCache, importedHandle,
+                                                             outHandle, &replacedHandle);
+                    break;
+                case Cache::LAYER_BUFFER:
+                    error = layerResource->getBuffer(slot, fromCache, importedHandle, outHandle,
+                                                     &replacedHandle);
+                    break;
+                case Cache::LAYER_SIDEBAND_STREAM:
+                    error = layerResource->getSidebandStream(slot, fromCache, importedHandle,
+                                                             outHandle, &replacedHandle);
+                    break;
+                default:
+                    error = Error::BAD_PARAMETER;
+                    break;
+            }
+
+            if (error != Error::NONE) {
+                ALOGW("invalid cache %d slot %d", int(cache), int(slot));
+            }
+        } else if (!displayResource) {
+            error = Error::BAD_DISPLAY;
+        } else {
+            error = Error::BAD_LAYER;
+        }
+
+        // clean up on errors
+        if (error != Error::NONE) {
+            if (!fromCache) {
+                if (isBuffer) {
+                    mImporter.freeBuffer(importedHandle);
+                } else {
+                    mImporter.freeStream(importedHandle);
+                }
+            }
+            return error;
+        }
+
+        outReplacedHandle->reset(&mImporter, replacedHandle);
+
+        return Error::NONE;
+    }
+};
+
+}  // namespace hal
+}  // namespace V2_1
+}  // namespace composer
+}  // namespace graphics
+}  // namespace hardware
+}  // namespace android