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Commit 85075869 authored by Andy McFadden's avatar Andy McFadden
Browse files

Wait for buffers to drain 

When a BufferQueue producer disconnects and reconnects, we retain
the previously-queued buffers but empty the slots.  This allows
the number of queued buffers to grow without limit.  The low-memory
killer does not approve.

Bug 11069934

Change-Id: Ia2eaa954c7a3904b54209a3701dba01689e204d8
parent dacd4159

libs/gui/BufferQueue.cpp

+30 −17
Original line number Diff line number Diff line
@@ -644,6 +644,7 @@ status_t BufferQueue::connect(const sp<IBinder>& token, 
            producerControlledByApp ? "true" : "false");

    Mutex::Autolock lock(mMutex);



retry:

    if (mAbandoned) {

        ST_LOGE("connect: BufferQueue has been abandoned!");

        return NO_INIT;
@@ -654,17 +655,30 @@ status_t BufferQueue::connect(const sp<IBinder>& token, 
        return NO_INIT;

    }



    if (mConnectedApi != NO_CONNECTED_API) {

        ST_LOGE("connect: already connected (cur=%d, req=%d)",

                mConnectedApi, api);

        return -EINVAL;

    }



    // If we disconnect and reconnect quickly, we can be in a state where our slots are

    // empty but we have many buffers in the queue.  This can cause us to run out of

    // memory if we outrun the consumer.  Wait here if it looks like we have too many

    // buffers queued up.

    int maxBufferCount = getMaxBufferCountLocked(false);    // worst-case, i.e. largest value

    if (mQueue.size() > (size_t) maxBufferCount) {

        // TODO: make this bound tighter?

        ST_LOGV("queue size is %d, waiting", mQueue.size());

        mDequeueCondition.wait(mMutex);

        goto retry;

    }



    int err = NO_ERROR;

    switch (api) {

        case NATIVE_WINDOW_API_EGL:

        case NATIVE_WINDOW_API_CPU:

        case NATIVE_WINDOW_API_MEDIA:

        case NATIVE_WINDOW_API_CAMERA:

            if (mConnectedApi != NO_CONNECTED_API) {

                ST_LOGE("connect: already connected (cur=%d, req=%d)",

                        mConnectedApi, api);

                err = -EINVAL;

            } else {

            mConnectedApi = api;

            output->inflate(mDefaultWidth, mDefaultHeight, mTransformHint, mQueue.size());
@@ -678,7 +692,6 @@ status_t BufferQueue::connect(const sp<IBinder>& token, 
                    ALOGE("linkToDeath failed: %s (%d)", strerror(-err), err);

                }

            }

            }

            break;

        default:

            err = -EINVAL;