BufferQueue: Add StreamSplitter
Adds a StreamSplitter class, that takes one IGraphicBufferConsumer
interface and multiple IGraphicBufferProducer interfaces and
implements a one-to-many broadcast of GraphicBuffers (while managing
fences correctly).
Change-Id: I38ecdf3e311ac521bc781c30dde0cc382a4376a3
diff --git a/include/gui/StreamSplitter.h b/include/gui/StreamSplitter.h
new file mode 100644
index 0000000..f927953
--- /dev/null
+++ b/include/gui/StreamSplitter.h
@@ -0,0 +1,184 @@
+/*
+ * Copyright 2014 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_GUI_STREAMSPLITTER_H
+#define ANDROID_GUI_STREAMSPLITTER_H
+
+#include <gui/IConsumerListener.h>
+#include <gui/IProducerListener.h>
+
+#include <utils/Condition.h>
+#include <utils/KeyedVector.h>
+#include <utils/Mutex.h>
+#include <utils/StrongPointer.h>
+
+namespace android {
+
+class GraphicBuffer;
+class IGraphicBufferConsumer;
+class IGraphicBufferProducer;
+
+// StreamSplitter is an autonomous class that manages one input BufferQueue
+// and multiple output BufferQueues. By using the buffer attach and detach logic
+// in BufferQueue, it is able to present the illusion of a single split
+// BufferQueue, where each buffer queued to the input is available to be
+// acquired by each of the outputs, and is able to be dequeued by the input
+// again only once all of the outputs have released it.
+class StreamSplitter : public BnConsumerListener {
+public:
+ // createSplitter creates a new splitter, outSplitter, using inputQueue as
+ // the input BufferQueue. Output BufferQueues must be added using addOutput
+ // before queueing any buffers to the input.
+ //
+ // A return value other than NO_ERROR means that an error has occurred and
+ // outSplitter has not been modified. BAD_VALUE is returned if inputQueue or
+ // outSplitter is NULL. See IGraphicBufferConsumer::consumerConnect for
+ // explanations of other error codes.
+ static status_t createSplitter(const sp<IGraphicBufferConsumer>& inputQueue,
+ sp<StreamSplitter>* outSplitter);
+
+ // addOutput adds an output BufferQueue to the splitter. The splitter
+ // connects to outputQueue as a CPU producer, and any buffers queued
+ // to the input will be queued to each output. It is assumed that all of the
+ // outputs are added before any buffers are queued on the input. If any
+ // output is abandoned by its consumer, the splitter will abandon its input
+ // queue (see onAbandoned).
+ //
+ // A return value other than NO_ERROR means that an error has occurred and
+ // outputQueue has not been added to the splitter. BAD_VALUE is returned if
+ // outputQueue is NULL. See IGraphicBufferProducer::connect for explanations
+ // of other error codes.
+ status_t addOutput(const sp<IGraphicBufferProducer>& outputQueue);
+
+ // setName sets the consumer name of the input queue
+ void setName(const String8& name);
+
+private:
+ // From IConsumerListener
+ //
+ // During this callback, we store some tracking information, detach the
+ // buffer from the input, and attach it to each of the outputs. This call
+ // can block if there are too many outstanding buffers. If it blocks, it
+ // will resume when onBufferReleasedByOutput releases a buffer back to the
+ // input.
+ virtual void onFrameAvailable();
+
+ // From IConsumerListener
+ // We don't care about released buffers because we detach each buffer as
+ // soon as we acquire it. See the comment for onBufferReleased below for
+ // some clarifying notes about the name.
+ virtual void onBuffersReleased() {}
+
+ // From IConsumerListener
+ // We don't care about sideband streams, since we won't be splitting them
+ virtual void onSidebandStreamChanged() {}
+
+ // This is the implementation of the onBufferReleased callback from
+ // IProducerListener. It gets called from an OutputListener (see below), and
+ // 'from' is which producer interface from which the callback was received.
+ //
+ // During this callback, we detach the buffer from the output queue that
+ // generated the callback, update our state tracking to see if this is the
+ // last output releasing the buffer, and if so, release it to the input.
+ // If we release the buffer to the input, we allow a blocked
+ // onFrameAvailable call to proceed.
+ void onBufferReleasedByOutput(const sp<IGraphicBufferProducer>& from);
+
+ // When this is called, the splitter disconnects from (i.e., abandons) its
+ // input queue and signals any waiting onFrameAvailable calls to wake up.
+ // It still processes callbacks from other outputs, but only detaches their
+ // buffers so they can continue operating until they run out of buffers to
+ // acquire. This must be called with mMutex locked.
+ void onAbandonedLocked();
+
+ // This is a thin wrapper class that lets us determine which BufferQueue
+ // the IProducerListener::onBufferReleased callback is associated with. We
+ // create one of these per output BufferQueue, and then pass the producer
+ // into onBufferReleasedByOutput above.
+ class OutputListener : public BnProducerListener,
+ public IBinder::DeathRecipient {
+ public:
+ OutputListener(const sp<StreamSplitter>& splitter,
+ const sp<IGraphicBufferProducer>& output);
+ virtual ~OutputListener();
+
+ // From IProducerListener
+ virtual void onBufferReleased();
+
+ // From IBinder::DeathRecipient
+ virtual void binderDied(const wp<IBinder>& who);
+
+ private:
+ sp<StreamSplitter> mSplitter;
+ sp<IGraphicBufferProducer> mOutput;
+ };
+
+ class BufferTracker : public LightRefBase<BufferTracker> {
+ public:
+ BufferTracker(const sp<GraphicBuffer>& buffer);
+
+ const sp<GraphicBuffer>& getBuffer() const { return mBuffer; }
+ const sp<Fence>& getMergedFence() const { return mMergedFence; }
+
+ void mergeFence(const sp<Fence>& with);
+
+ // Returns the new value
+ // Only called while mMutex is held
+ size_t incrementReleaseCountLocked() { return ++mReleaseCount; }
+
+ private:
+ // Only destroy through LightRefBase
+ friend LightRefBase<BufferTracker>;
+ ~BufferTracker();
+
+ // Disallow copying
+ BufferTracker(const BufferTracker& other);
+ BufferTracker& operator=(const BufferTracker& other);
+
+ sp<GraphicBuffer> mBuffer; // One instance that holds this native handle
+ sp<Fence> mMergedFence;
+ size_t mReleaseCount;
+ };
+
+ // Only called from createSplitter
+ StreamSplitter(const sp<IGraphicBufferConsumer>& inputQueue);
+
+ // Must be accessed through RefBase
+ virtual ~StreamSplitter();
+
+ static const int MAX_OUTSTANDING_BUFFERS = 2;
+
+ // mIsAbandoned is set to true when an output dies. Once the StreamSplitter
+ // has been abandoned, it will continue to detach buffers from other
+ // outputs, but it will disconnect from the input and not attempt to
+ // communicate with it further.
+ bool mIsAbandoned;
+
+ Mutex mMutex;
+ Condition mReleaseCondition;
+ int mOutstandingBuffers;
+ sp<IGraphicBufferConsumer> mInput;
+ Vector<sp<IGraphicBufferProducer> > mOutputs;
+
+ // Map of GraphicBuffer IDs (GraphicBuffer::getId()) to buffer tracking
+ // objects (which are mostly for counting how many outputs have released the
+ // buffer, but also contain merged release fences).
+ KeyedVector<uint64_t, sp<BufferTracker> > mBuffers;
+};
+
+} // namespace android
+
+#endif