diff --git a/media/libmediatranscoding/TranscodingSessionController.cpp b/media/libmediatranscoding/TranscodingSessionController.cpp
new file mode 100644
index 0000000..2306395
--- /dev/null
+++ b/media/libmediatranscoding/TranscodingSessionController.cpp
@@ -0,0 +1,574 @@
+/*
+ * Copyright (C) 2020 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 "TranscodingSessionController"
+
+#define VALIDATE_STATE 1
+
+#include <inttypes.h>
+#include <media/TranscodingSessionController.h>
+#include <media/TranscodingUidPolicy.h>
+#include <utils/Log.h>
+
+#include <utility>
+
+namespace android {
+
+static_assert((SessionIdType)-1 < 0, "SessionIdType should be signed");
+
+constexpr static uid_t OFFLINE_UID = -1;
+
+//static
+String8 TranscodingSessionController::sessionToString(const SessionKeyType& sessionKey) {
+    return String8::format("{client:%lld, session:%d}", (long long)sessionKey.first,
+                           sessionKey.second);
+}
+
+//static
+const char* TranscodingSessionController::sessionStateToString(const Session::State sessionState) {
+    switch (sessionState) {
+    case Session::State::NOT_STARTED:
+        return "NOT_STARTED";
+    case Session::State::RUNNING:
+        return "RUNNING";
+    case Session::State::PAUSED:
+        return "PAUSED";
+    default:
+        break;
+    }
+    return "(unknown)";
+}
+
+TranscodingSessionController::TranscodingSessionController(
+        const std::shared_ptr<TranscoderInterface>& transcoder,
+        const std::shared_ptr<UidPolicyInterface>& uidPolicy,
+        const std::shared_ptr<ResourcePolicyInterface>& resourcePolicy)
+      : mTranscoder(transcoder),
+        mUidPolicy(uidPolicy),
+        mResourcePolicy(resourcePolicy),
+        mCurrentSession(nullptr),
+        mResourceLost(false) {
+    // Only push empty offline queue initially. Realtime queues are added when requests come in.
+    mUidSortedList.push_back(OFFLINE_UID);
+    mOfflineUidIterator = mUidSortedList.begin();
+    mSessionQueues.emplace(OFFLINE_UID, SessionQueueType());
+}
+
+TranscodingSessionController::~TranscodingSessionController() {}
+
+void TranscodingSessionController::dumpAllSessions(int fd, const Vector<String16>& args __unused) {
+    String8 result;
+
+    const size_t SIZE = 256;
+    char buffer[SIZE];
+    std::scoped_lock lock{mLock};
+
+    snprintf(buffer, SIZE, "\n========== Dumping all sessions queues =========\n");
+    result.append(buffer);
+    snprintf(buffer, SIZE, "  Total num of Sessions: %zu\n", mSessionMap.size());
+    result.append(buffer);
+
+    std::vector<int32_t> uids(mUidSortedList.begin(), mUidSortedList.end());
+    // Exclude last uid, which is for offline queue
+    uids.pop_back();
+    std::vector<std::string> packageNames;
+    if (TranscodingUidPolicy::getNamesForUids(uids, &packageNames)) {
+        uids.push_back(OFFLINE_UID);
+        packageNames.push_back("(offline)");
+    }
+
+    for (int32_t i = 0; i < uids.size(); i++) {
+        const uid_t uid = uids[i];
+
+        if (mSessionQueues[uid].empty()) {
+            continue;
+        }
+        snprintf(buffer, SIZE, "    Uid: %d, pkg: %s\n", uid,
+                 packageNames.empty() ? "(unknown)" : packageNames[i].c_str());
+        result.append(buffer);
+        snprintf(buffer, SIZE, "      Num of sessions: %zu\n", mSessionQueues[uid].size());
+        result.append(buffer);
+        for (auto& sessionKey : mSessionQueues[uid]) {
+            auto sessionIt = mSessionMap.find(sessionKey);
+            if (sessionIt == mSessionMap.end()) {
+                snprintf(buffer, SIZE, "Failed to look up Session %s  \n",
+                         sessionToString(sessionKey).c_str());
+                result.append(buffer);
+                continue;
+            }
+            Session& session = sessionIt->second;
+            TranscodingRequestParcel& request = session.request;
+            snprintf(buffer, SIZE, "      Session: %s, %s, %d%%\n",
+                     sessionToString(sessionKey).c_str(), sessionStateToString(session.state),
+                     session.lastProgress);
+            result.append(buffer);
+            snprintf(buffer, SIZE, "        Src: %s\n", request.sourceFilePath.c_str());
+            result.append(buffer);
+            snprintf(buffer, SIZE, "        Dst: %s\n", request.destinationFilePath.c_str());
+            result.append(buffer);
+        }
+    }
+
+    write(fd, result.string(), result.size());
+}
+
+TranscodingSessionController::Session* TranscodingSessionController::getTopSession_l() {
+    if (mSessionMap.empty()) {
+        return nullptr;
+    }
+    uid_t topUid = *mUidSortedList.begin();
+    SessionKeyType topSessionKey = *mSessionQueues[topUid].begin();
+    return &mSessionMap[topSessionKey];
+}
+
+void TranscodingSessionController::updateCurrentSession_l() {
+    Session* topSession = getTopSession_l();
+    Session* curSession = mCurrentSession;
+    ALOGV("updateCurrentSession: topSession is %s, curSession is %s",
+          topSession == nullptr ? "null" : sessionToString(topSession->key).c_str(),
+          curSession == nullptr ? "null" : sessionToString(curSession->key).c_str());
+
+    // If we found a topSession that should be run, and it's not already running,
+    // take some actions to ensure it's running.
+    if (topSession != nullptr &&
+        (topSession != curSession || topSession->state != Session::RUNNING)) {
+        // If another session is currently running, pause it first.
+        if (curSession != nullptr && curSession->state == Session::RUNNING) {
+            mTranscoder->pause(curSession->key.first, curSession->key.second);
+            curSession->state = Session::PAUSED;
+        }
+        // If we are not experiencing resource loss, we can start or resume
+        // the topSession now.
+        if (!mResourceLost) {
+            if (topSession->state == Session::NOT_STARTED) {
+                mTranscoder->start(topSession->key.first, topSession->key.second,
+                                   topSession->request, topSession->callback.lock());
+            } else if (topSession->state == Session::PAUSED) {
+                mTranscoder->resume(topSession->key.first, topSession->key.second,
+                                    topSession->request, topSession->callback.lock());
+            }
+            topSession->state = Session::RUNNING;
+        }
+    }
+    mCurrentSession = topSession;
+}
+
+void TranscodingSessionController::removeSession_l(const SessionKeyType& sessionKey) {
+    ALOGV("%s: session %s", __FUNCTION__, sessionToString(sessionKey).c_str());
+
+    if (mSessionMap.count(sessionKey) == 0) {
+        ALOGE("session %s doesn't exist", sessionToString(sessionKey).c_str());
+        return;
+    }
+
+    // Remove session from uid's queue.
+    const uid_t uid = mSessionMap[sessionKey].uid;
+    SessionQueueType& sessionQueue = mSessionQueues[uid];
+    auto it = std::find(sessionQueue.begin(), sessionQueue.end(), sessionKey);
+    if (it == sessionQueue.end()) {
+        ALOGE("couldn't find session %s in queue for uid %d", sessionToString(sessionKey).c_str(),
+              uid);
+        return;
+    }
+    sessionQueue.erase(it);
+
+    // If this is the last session in a real-time queue, remove this uid's queue.
+    if (uid != OFFLINE_UID && sessionQueue.empty()) {
+        mUidSortedList.remove(uid);
+        mSessionQueues.erase(uid);
+        mUidPolicy->unregisterMonitorUid(uid);
+
+        std::unordered_set<uid_t> topUids = mUidPolicy->getTopUids();
+        moveUidsToTop_l(topUids, false /*preserveTopUid*/);
+    }
+
+    // Clear current session.
+    if (mCurrentSession == &mSessionMap[sessionKey]) {
+        mCurrentSession = nullptr;
+    }
+
+    // Remove session from session map.
+    mSessionMap.erase(sessionKey);
+}
+
+/**
+ * Moves the set of uids to the front of mUidSortedList (which is used to pick
+ * the next session to run).
+ *
+ * This is called when 1) we received a onTopUidsChanged() callback from UidPolicy,
+ * or 2) we removed the session queue for a uid because it becomes empty.
+ *
+ * In case of 1), if there are multiple uids in the set, and the current front
+ * uid in mUidSortedList is still in the set, we try to keep that uid at front
+ * so that current session run is not interrupted. (This is not a concern for case 2)
+ * because the queue for a uid was just removed entirely.)
+ */
+void TranscodingSessionController::moveUidsToTop_l(const std::unordered_set<uid_t>& uids,
+                                                   bool preserveTopUid) {
+    // If uid set is empty, nothing to do. Do not change the queue status.
+    if (uids.empty()) {
+        return;
+    }
+
+    // Save the current top uid.
+    uid_t curTopUid = *mUidSortedList.begin();
+    bool pushCurTopToFront = false;
+    int32_t numUidsMoved = 0;
+
+    // Go through the sorted uid list once, and move the ones in top set to front.
+    for (auto it = mUidSortedList.begin(); it != mUidSortedList.end();) {
+        uid_t uid = *it;
+
+        if (uid != OFFLINE_UID && uids.count(uid) > 0) {
+            it = mUidSortedList.erase(it);
+
+            // If this is the top we're preserving, don't push it here, push
+            // it after the for-loop.
+            if (uid == curTopUid && preserveTopUid) {
+                pushCurTopToFront = true;
+            } else {
+                mUidSortedList.push_front(uid);
+            }
+
+            // If we found all uids in the set, break out.
+            if (++numUidsMoved == uids.size()) {
+                break;
+            }
+        } else {
+            ++it;
+        }
+    }
+
+    if (pushCurTopToFront) {
+        mUidSortedList.push_front(curTopUid);
+    }
+}
+
+bool TranscodingSessionController::submit(
+        ClientIdType clientId, SessionIdType sessionId, uid_t uid,
+        const TranscodingRequestParcel& request,
+        const std::weak_ptr<ITranscodingClientCallback>& callback) {
+    SessionKeyType sessionKey = std::make_pair(clientId, sessionId);
+
+    ALOGV("%s: session %s, uid %d, prioirty %d", __FUNCTION__, sessionToString(sessionKey).c_str(),
+          uid, (int32_t)request.priority);
+
+    std::scoped_lock lock{mLock};
+
+    if (mSessionMap.count(sessionKey) > 0) {
+        ALOGE("session %s already exists", sessionToString(sessionKey).c_str());
+        return false;
+    }
+
+    // TODO(chz): only support offline vs real-time for now. All kUnspecified sessions
+    // go to offline queue.
+    if (request.priority == TranscodingSessionPriority::kUnspecified) {
+        uid = OFFLINE_UID;
+    }
+
+    // Add session to session map.
+    mSessionMap[sessionKey].key = sessionKey;
+    mSessionMap[sessionKey].uid = uid;
+    mSessionMap[sessionKey].state = Session::NOT_STARTED;
+    mSessionMap[sessionKey].lastProgress = 0;
+    mSessionMap[sessionKey].request = request;
+    mSessionMap[sessionKey].callback = callback;
+
+    // If it's an offline session, the queue was already added in constructor.
+    // If it's a real-time sessions, check if a queue is already present for the uid,
+    // and add a new queue if needed.
+    if (uid != OFFLINE_UID) {
+        if (mSessionQueues.count(uid) == 0) {
+            mUidPolicy->registerMonitorUid(uid);
+            if (mUidPolicy->isUidOnTop(uid)) {
+                mUidSortedList.push_front(uid);
+            } else {
+                // Shouldn't be submitting real-time requests from non-top app,
+                // put it in front of the offline queue.
+                mUidSortedList.insert(mOfflineUidIterator, uid);
+            }
+        } else if (uid != *mUidSortedList.begin()) {
+            if (mUidPolicy->isUidOnTop(uid)) {
+                mUidSortedList.remove(uid);
+                mUidSortedList.push_front(uid);
+            }
+        }
+    }
+    // Append this session to the uid's queue.
+    mSessionQueues[uid].push_back(sessionKey);
+
+    updateCurrentSession_l();
+
+    validateState_l();
+    return true;
+}
+
+bool TranscodingSessionController::cancel(ClientIdType clientId, SessionIdType sessionId) {
+    SessionKeyType sessionKey = std::make_pair(clientId, sessionId);
+
+    ALOGV("%s: session %s", __FUNCTION__, sessionToString(sessionKey).c_str());
+
+    std::list<SessionKeyType> sessionsToRemove;
+
+    std::scoped_lock lock{mLock};
+
+    if (sessionId < 0) {
+        for (auto it = mSessionMap.begin(); it != mSessionMap.end(); ++it) {
+            if (it->first.first == clientId && it->second.uid != OFFLINE_UID) {
+                sessionsToRemove.push_back(it->first);
+            }
+        }
+    } else {
+        if (mSessionMap.count(sessionKey) == 0) {
+            ALOGE("session %s doesn't exist", sessionToString(sessionKey).c_str());
+            return false;
+        }
+        sessionsToRemove.push_back(sessionKey);
+    }
+
+    for (auto it = sessionsToRemove.begin(); it != sessionsToRemove.end(); ++it) {
+        // If the session has ever been started, stop it now.
+        // Note that stop() is needed even if the session is currently paused. This instructs
+        // the transcoder to discard any states for the session, otherwise the states may
+        // never be discarded.
+        if (mSessionMap[*it].state != Session::NOT_STARTED) {
+            mTranscoder->stop(it->first, it->second);
+        }
+
+        // Remove the session.
+        removeSession_l(*it);
+    }
+
+    // Start next session.
+    updateCurrentSession_l();
+
+    validateState_l();
+    return true;
+}
+
+bool TranscodingSessionController::getSession(ClientIdType clientId, SessionIdType sessionId,
+                                              TranscodingRequestParcel* request) {
+    SessionKeyType sessionKey = std::make_pair(clientId, sessionId);
+
+    std::scoped_lock lock{mLock};
+
+    if (mSessionMap.count(sessionKey) == 0) {
+        ALOGE("session %s doesn't exist", sessionToString(sessionKey).c_str());
+        return false;
+    }
+
+    *(TranscodingRequest*)request = mSessionMap[sessionKey].request;
+    return true;
+}
+
+void TranscodingSessionController::notifyClient(ClientIdType clientId, SessionIdType sessionId,
+                                                const char* reason,
+                                                std::function<void(const SessionKeyType&)> func) {
+    SessionKeyType sessionKey = std::make_pair(clientId, sessionId);
+
+    std::scoped_lock lock{mLock};
+
+    if (mSessionMap.count(sessionKey) == 0) {
+        ALOGW("%s: ignoring %s for session %s that doesn't exist", __FUNCTION__, reason,
+              sessionToString(sessionKey).c_str());
+        return;
+    }
+
+    // Only ignore if session was never started. In particular, propagate the status
+    // to client if the session is paused. Transcoder could have posted finish when
+    // we're pausing it, and the finish arrived after we changed current session.
+    if (mSessionMap[sessionKey].state == Session::NOT_STARTED) {
+        ALOGW("%s: ignoring %s for session %s that was never started", __FUNCTION__, reason,
+              sessionToString(sessionKey).c_str());
+        return;
+    }
+
+    ALOGV("%s: session %s %s", __FUNCTION__, sessionToString(sessionKey).c_str(), reason);
+    func(sessionKey);
+}
+
+void TranscodingSessionController::onStarted(ClientIdType clientId, SessionIdType sessionId) {
+    notifyClient(clientId, sessionId, "started", [=](const SessionKeyType& sessionKey) {
+        auto callback = mSessionMap[sessionKey].callback.lock();
+        if (callback != nullptr) {
+            callback->onTranscodingStarted(sessionId);
+        }
+    });
+}
+
+void TranscodingSessionController::onPaused(ClientIdType clientId, SessionIdType sessionId) {
+    notifyClient(clientId, sessionId, "paused", [=](const SessionKeyType& sessionKey) {
+        auto callback = mSessionMap[sessionKey].callback.lock();
+        if (callback != nullptr) {
+            callback->onTranscodingPaused(sessionId);
+        }
+    });
+}
+
+void TranscodingSessionController::onResumed(ClientIdType clientId, SessionIdType sessionId) {
+    notifyClient(clientId, sessionId, "resumed", [=](const SessionKeyType& sessionKey) {
+        auto callback = mSessionMap[sessionKey].callback.lock();
+        if (callback != nullptr) {
+            callback->onTranscodingResumed(sessionId);
+        }
+    });
+}
+
+void TranscodingSessionController::onFinish(ClientIdType clientId, SessionIdType sessionId) {
+    notifyClient(clientId, sessionId, "finish", [=](const SessionKeyType& sessionKey) {
+        {
+            auto clientCallback = mSessionMap[sessionKey].callback.lock();
+            if (clientCallback != nullptr) {
+                clientCallback->onTranscodingFinished(
+                        sessionId, TranscodingResultParcel({sessionId, -1 /*actualBitrateBps*/,
+                                                            std::nullopt /*sessionStats*/}));
+            }
+        }
+
+        // Remove the session.
+        removeSession_l(sessionKey);
+
+        // Start next session.
+        updateCurrentSession_l();
+
+        validateState_l();
+    });
+}
+
+void TranscodingSessionController::onError(ClientIdType clientId, SessionIdType sessionId,
+                                           TranscodingErrorCode err) {
+    notifyClient(clientId, sessionId, "error", [=](const SessionKeyType& sessionKey) {
+        {
+            auto clientCallback = mSessionMap[sessionKey].callback.lock();
+            if (clientCallback != nullptr) {
+                clientCallback->onTranscodingFailed(sessionId, err);
+            }
+        }
+
+        // Remove the session.
+        removeSession_l(sessionKey);
+
+        // Start next session.
+        updateCurrentSession_l();
+
+        validateState_l();
+    });
+}
+
+void TranscodingSessionController::onProgressUpdate(ClientIdType clientId, SessionIdType sessionId,
+                                                    int32_t progress) {
+    notifyClient(clientId, sessionId, "progress", [=](const SessionKeyType& sessionKey) {
+        auto callback = mSessionMap[sessionKey].callback.lock();
+        if (callback != nullptr) {
+            callback->onProgressUpdate(sessionId, progress);
+        }
+        mSessionMap[sessionKey].lastProgress = progress;
+    });
+}
+
+void TranscodingSessionController::onResourceLost() {
+    ALOGI("%s", __FUNCTION__);
+
+    std::scoped_lock lock{mLock};
+
+    if (mResourceLost) {
+        return;
+    }
+
+    // If we receive a resource loss event, the TranscoderLibrary already paused
+    // the transcoding, so we don't need to call onPaused to notify it to pause.
+    // Only need to update the session state here.
+    if (mCurrentSession != nullptr && mCurrentSession->state == Session::RUNNING) {
+        mCurrentSession->state = Session::PAUSED;
+        // Notify the client as a paused event.
+        auto clientCallback = mCurrentSession->callback.lock();
+        if (clientCallback != nullptr) {
+            clientCallback->onTranscodingPaused(mCurrentSession->key.second);
+        }
+    }
+    mResourceLost = true;
+
+    validateState_l();
+}
+
+void TranscodingSessionController::onTopUidsChanged(const std::unordered_set<uid_t>& uids) {
+    if (uids.empty()) {
+        ALOGW("%s: ignoring empty uids", __FUNCTION__);
+        return;
+    }
+
+    std::string uidStr;
+    for (auto it = uids.begin(); it != uids.end(); it++) {
+        if (!uidStr.empty()) {
+            uidStr += ", ";
+        }
+        uidStr += std::to_string(*it);
+    }
+
+    ALOGD("%s: topUids: size %zu, uids: %s", __FUNCTION__, uids.size(), uidStr.c_str());
+
+    std::scoped_lock lock{mLock};
+
+    moveUidsToTop_l(uids, true /*preserveTopUid*/);
+
+    updateCurrentSession_l();
+
+    validateState_l();
+}
+
+void TranscodingSessionController::onResourceAvailable() {
+    std::scoped_lock lock{mLock};
+
+    if (!mResourceLost) {
+        return;
+    }
+
+    ALOGI("%s", __FUNCTION__);
+
+    mResourceLost = false;
+    updateCurrentSession_l();
+
+    validateState_l();
+}
+
+void TranscodingSessionController::validateState_l() {
+#ifdef VALIDATE_STATE
+    LOG_ALWAYS_FATAL_IF(mSessionQueues.count(OFFLINE_UID) != 1,
+                        "mSessionQueues offline queue number is not 1");
+    LOG_ALWAYS_FATAL_IF(*mOfflineUidIterator != OFFLINE_UID,
+                        "mOfflineUidIterator not pointing to offline uid");
+    LOG_ALWAYS_FATAL_IF(mUidSortedList.size() != mSessionQueues.size(),
+                        "mUidList and mSessionQueues size mismatch");
+
+    int32_t totalSessions = 0;
+    for (auto uid : mUidSortedList) {
+        LOG_ALWAYS_FATAL_IF(mSessionQueues.count(uid) != 1,
+                            "mSessionQueues count for uid %d is not 1", uid);
+        for (auto& sessionKey : mSessionQueues[uid]) {
+            LOG_ALWAYS_FATAL_IF(mSessionMap.count(sessionKey) != 1,
+                                "mSessions count for session %s is not 1",
+                                sessionToString(sessionKey).c_str());
+        }
+
+        totalSessions += mSessionQueues[uid].size();
+    }
+    LOG_ALWAYS_FATAL_IF(mSessionMap.size() != totalSessions,
+                        "mSessions size doesn't match total sessions counted from uid queues");
+#endif  // VALIDATE_STATE
+}
+
+}  // namespace android