virtual status_t consumerDisconnect() { return disconnect(); }

// disconnect disconnects a consumer from the BufferQueue. All
// buffers will be freed and the BufferQueue is placed in the "abandoned"
// state, causing most interactions with the BufferQueue by the producer to
// fail.
status_t BufferQueueConsumer::disconnect() {
    ATRACE_CALL();

    BQ_LOGV("disconnect");

    std::lock_guard<std::mutex> lock(mCore->mMutex);

    if (mCore->mConsumerListener == nullptr) {
        BQ_LOGE("disconnect: no consumer is connected");
        return BAD_VALUE;
    }

    mCore->mIsAbandoned = true;
    mCore->mConsumerListener = nullptr;
    mCore->mQueue.clear();
    mCore->freeAllBuffersLocked();
    mCore->mSharedBufferSlot = BufferQueueCore::INVALID_BUFFER_SLOT;
    mCore->mDequeueCondition.notify_all();
    return NO_ERROR;
}

• consumerDisconnect() 是 IGraphicBufferConsumer 的接口，在 BufferQueueConsumer 的实现是调用 disconnect()。
• 在 BufferQueueConsumer::connect() 必须传递有效 ConsumerListener，因此，mConsumerListener 是 nullptr 表示还未连接。
• 清空 mQueue，调用 BufferQueueCore::freeAllBuffersLocked() 释放所有 buffer。通知 mDequeueCondition。