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* Copyright (C) 2010 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
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <gui/BufferQueue.h>
#include <ui/GraphicBuffer.h>
#include <utils/String8.h>
#include <utils/Vector.h>
#include <utils/threads.h>
namespace android {
// ----------------------------------------------------------------------------
class String8;
// ConsumerBase is a base class for BufferQueue consumer end-points. It
// handles common tasks like management of the connection to the BufferQueue
// and the buffer pool.
class ConsumerBase : public virtual RefBase,
protected BufferQueue::ConsumerListener {
struct FrameAvailableListener : public virtual RefBase {
// onFrameAvailable() is called each time an additional frame becomes
// available for consumption. This means that frames that are queued
// while in asynchronous mode only trigger the callback if no previous
// frames are pending. Frames queued while in synchronous mode always
// trigger the callback.
// This is called without any lock held and can be called concurrently
// by multiple threads.
virtual void onFrameAvailable() = 0;
virtual ~ConsumerBase();
// abandon frees all the buffers and puts the ConsumerBase into the
// 'abandoned' state. Once put in this state the ConsumerBase can never
// leave it. When in the 'abandoned' state, all methods of the
// ISurfaceTexture interface will fail with the NO_INIT error.
// Note that while calling this method causes all the buffers to be freed
// from the perspective of the the ConsumerBase, if there are additional
// references on the buffers (e.g. if a buffer is referenced by a client
// or by OpenGL ES as a texture) then those buffer will remain allocated.
void abandon();
// set the name of the ConsumerBase that will be used to identify it in
// log messages.
void setName(const String8& name);
// getBufferQueue returns the BufferQueue object to which this
// ConsumerBase is connected.
sp<BufferQueue> getBufferQueue() const;
// dump writes the current state to a string. These methods should NOT be
// overridden by child classes. Instead they should override the
// dumpLocked method, which is called by these methods after locking the
// mutex.
void dump(String8& result) const;
void dump(String8& result, const char* prefix, char* buffer, size_t SIZE) const;
// setFrameAvailableListener sets the listener object that will be notified
// when a new frame becomes available.
void setFrameAvailableListener(const sp<FrameAvailableListener>& listener);
ConsumerBase(const ConsumerBase&);
void operator=(const ConsumerBase&);
// ConsumerBase constructs a new ConsumerBase object to consume image
// buffers from the given BufferQueue.
ConsumerBase(const sp<BufferQueue> &bufferQueue);
// Implementation of the BufferQueue::ConsumerListener interface. These
// calls are used to notify the ConsumerBase of asynchronous events in the
// BufferQueue. These methods should not need to be overridden by derived
// classes, but if they are overridden the ConsumerBase implementation
// must be called from the derived class.
virtual void onFrameAvailable();
virtual void onBuffersReleased();
// freeBufferLocked frees up the given buffer slot. If the slot has been
// initialized this will release the reference to the GraphicBuffer in that
// slot. Otherwise it has no effect.
// Derived classes should override this method to clean up any state they
// keep per slot. If it is overridden, the derived class's implementation
// must call ConsumerBase::freeBufferLocked.
// This method must be called with mMutex locked.
virtual void freeBufferLocked(int slotIndex);
// abandonLocked puts the BufferQueue into the abandoned state, causing
// all future operations on it to fail. This method rather than the public
// abandon method should be overridden by child classes to add abandon-
// time behavior.
// Derived classes should override this method to clean up any object
// state they keep (as opposed to per-slot state). If it is overridden,
// the derived class's implementation must call ConsumerBase::abandonLocked.
// This method must be called with mMutex locked.
virtual void abandonLocked();
// dumpLocked dumps the current state of the ConsumerBase object to the
// result string. Each line is prefixed with the string pointed to by the
// prefix argument. The buffer argument points to a buffer that may be
// used for intermediate formatting data, and the size of that buffer is
// indicated by the size argument.
// Derived classes should override this method to dump their internal
// state. If this method is overridden the derived class's implementation
// should call ConsumerBase::dumpLocked.
// This method must be called with mMutex locked.
virtual void dumpLocked(String8& result, const char* prefix, char* buffer,
size_t size) const;
// acquireBufferLocked fetches the next buffer from the BufferQueue and
// updates the buffer slot for the buffer returned.
// Derived classes should override this method to perform any
// initialization that must take place the first time a buffer is assigned
// to a slot. If it is overridden the derived class's implementation must
// call ConsumerBase::acquireBufferLocked.
virtual status_t acquireBufferLocked(BufferQueue::BufferItem *item);
// releaseBufferLocked relinquishes control over a buffer, returning that
// control to the BufferQueue.
// Derived classes should override this method to perform any cleanup that
// must take place when a buffer is released back to the BufferQueue. If
// it is overridden the derived class's implementation must call
// ConsumerBase::releaseBufferLocked.
virtual status_t releaseBufferLocked(int buf, EGLDisplay display,
EGLSyncKHR eglFence);
// addReleaseFence* adds the sync points associated with a fence to the set
// of sync points that must be reached before the buffer in the given slot
// may be used after the slot has been released. This should be called by
// derived classes each time some asynchronous work is kicked off that
// references the buffer.
status_t addReleaseFence(int slot, const sp<Fence>& fence);
status_t addReleaseFenceLocked(int slot, const sp<Fence>& fence);
// Slot contains the information and object references that
// ConsumerBase maintains about a BufferQueue buffer slot.
struct Slot {
// mGraphicBuffer is the Gralloc buffer store in the slot or NULL if
// no Gralloc buffer is in the slot.
sp<GraphicBuffer> mGraphicBuffer;
// mFence is a fence which will signal when the buffer associated with
// this buffer slot is no longer being used by the consumer and can be
// overwritten. The buffer can be dequeued before the fence signals;
// the producer is responsible for delaying writes until it signals.
sp<Fence> mFence;
// mSlots stores the buffers that have been allocated by the BufferQueue
// for each buffer slot. It is initialized to null pointers, and gets
// filled in with the result of BufferQueue::acquire when the
// client dequeues a buffer from a
// slot that has not yet been used. The buffer allocated to a slot will also
// be replaced if the requested buffer usage or geometry differs from that
// of the buffer allocated to a slot.
Slot mSlots[BufferQueue::NUM_BUFFER_SLOTS];
// mAbandoned indicates that the BufferQueue will no longer be used to
// consume images buffers pushed to it using the ISurfaceTexture
// interface. It is initialized to false, and set to true in the abandon
// method. A BufferQueue that has been abandoned will return the NO_INIT
// error from all IConsumerBase methods capable of returning an error.
bool mAbandoned;
// mName is a string used to identify the ConsumerBase in log messages.
// It can be set by the setName method.
String8 mName;
// mFrameAvailableListener is the listener object that will be called when a
// new frame becomes available. If it is not NULL it will be called from
// queueBuffer.
sp<FrameAvailableListener> mFrameAvailableListener;
// The ConsumerBase has-a BufferQueue and is responsible for creating this object
// if none is supplied
sp<BufferQueue> mBufferQueue;
// mMutex is the mutex used to prevent concurrent access to the member
// variables of ConsumerBase objects. It must be locked whenever the
// member variables are accessed or when any of the *Locked methods are
// called.
// This mutex is intended to be locked by derived classes.
mutable Mutex mMutex;
// ----------------------------------------------------------------------------
}; // namespace android