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* Copyright (C) 2012 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 <EGL/egl.h>
#include <EGL/eglext.h>
#include <gui/IGraphicBufferAlloc.h>
#include <gui/ISurfaceTexture.h>
#include <ui/Fence.h>
#include <ui/GraphicBuffer.h>
#include <utils/String8.h>
#include <utils/Vector.h>
#include <utils/threads.h>
namespace android {
// ----------------------------------------------------------------------------
class BufferQueue : public BnSurfaceTexture {
enum { NUM_BUFFER_SLOTS = 32 };
enum { NO_CONNECTED_API = 0 };
enum { INVALID_BUFFER_SLOT = -1 };
// When in async mode we reserve two slots in order to guarantee that the
// producer and consumer can run asynchronously.
// ConsumerListener is the interface through which the BufferQueue notifies
// the consumer of events that the consumer may wish to react to. Because
// the consumer will generally have a mutex that is locked during calls from
// teh consumer to the BufferQueue, these calls from the BufferQueue to the
// consumer *MUST* be called only when the BufferQueue mutex is NOT locked.
struct ConsumerListener : public virtual RefBase {
// onFrameAvailable is called from queueBuffer 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;
// onBuffersReleased is called to notify the buffer consumer that the
// BufferQueue has released its references to one or more GraphicBuffers
// contained in its slots. The buffer consumer should then call
// BufferQueue::getReleasedBuffers to retrieve the list of buffers
// This is called without any lock held and can be called concurrently
// by multiple threads.
virtual void onBuffersReleased() = 0;
// ProxyConsumerListener is a ConsumerListener implementation that keeps a weak
// reference to the actual consumer object. It forwards all calls to that
// consumer object so long as it exists.
// This class exists to avoid having a circular reference between the
// BufferQueue object and the consumer object. The reason this can't be a weak
// reference in the BufferQueue class is because we're planning to expose the
// consumer side of a BufferQueue as a binder interface, which doesn't support
// weak references.
class ProxyConsumerListener : public BufferQueue::ConsumerListener {
ProxyConsumerListener(const wp<BufferQueue::ConsumerListener>& consumerListener);
virtual ~ProxyConsumerListener();
virtual void onFrameAvailable();
virtual void onBuffersReleased();
// mConsumerListener is a weak reference to the ConsumerListener. This is
// the raison d'etre of ProxyConsumerListener.
wp<BufferQueue::ConsumerListener> mConsumerListener;
// BufferQueue manages a pool of gralloc memory slots to be used by
// producers and consumers. allowSynchronousMode specifies whether or not
// synchronous mode can be enabled by the producer. allocator is used to
// allocate all the needed gralloc buffers.
BufferQueue(bool allowSynchronousMode = true,
const sp<IGraphicBufferAlloc>& allocator = NULL);
virtual ~BufferQueue();
virtual int query(int what, int* value);
// setBufferCount updates the number of available buffer slots. After
// calling this all buffer slots are both unallocated and owned by the
// BufferQueue object (i.e. they are not owned by the client).
virtual status_t setBufferCount(int bufferCount);
virtual status_t requestBuffer(int slot, sp<GraphicBuffer>* buf);
// dequeueBuffer gets the next buffer slot index for the client to use. If a
// buffer slot is available then that slot index is written to the location
// pointed to by the buf argument and a status of OK is returned. If no
// slot is available then a status of -EBUSY is returned and buf is
// unmodified.
// The fence parameter will be updated to hold the fence associated with
// the buffer. The contents of the buffer must not be overwritten until the
// fence signals. If the fence is NULL, the buffer may be written
// immediately.
// The width and height parameters must be no greater than the minimum of
// An error due to invalid dimensions might not be reported until
// updateTexImage() is called.
virtual status_t dequeueBuffer(int *buf, sp<Fence>& fence,
uint32_t width, uint32_t height, uint32_t format, uint32_t usage);
// queueBuffer returns a filled buffer to the BufferQueue. In addition, a
// timestamp must be provided for the buffer. The timestamp is in
// nanoseconds, and must be monotonically increasing. Its other semantics
// (zero point, etc) are client-dependent and should be documented by the
// client.
virtual status_t queueBuffer(int buf,
const QueueBufferInput& input, QueueBufferOutput* output);
virtual void cancelBuffer(int buf, sp<Fence> fence);
// setSynchronousMode set whether dequeueBuffer is synchronous or
// asynchronous. In synchronous mode, dequeueBuffer blocks until
// a buffer is available, the currently bound buffer can be dequeued and
// queued buffers will be retired in order.
// The default mode is asynchronous.
virtual status_t setSynchronousMode(bool enabled);
// connect attempts to connect a producer client API to the BufferQueue.
// This must be called before any other ISurfaceTexture methods are called
// except for getAllocator.
// This method will fail if the connect was previously called on the
// BufferQueue and no corresponding disconnect call was made.
virtual status_t connect(int api, QueueBufferOutput* output);
// disconnect attempts to disconnect a producer client API from the
// BufferQueue. Calling this method will cause any subsequent calls to other
// ISurfaceTexture methods to fail except for getAllocator and connect.
// Successfully calling connect after this will allow the other methods to
// succeed again.
// This method will fail if the the BufferQueue is not currently
// connected to the specified client API.
virtual status_t disconnect(int api);
// dump our state in a String
virtual void dump(String8& result) const;
virtual void dump(String8& result, const char* prefix, char* buffer, size_t SIZE) const;
// public facing structure for BufferSlot
struct BufferItem {
// mGraphicBuffer points to the buffer allocated for this slot or is NULL
// if no buffer has been allocated.
sp<GraphicBuffer> mGraphicBuffer;
// mCrop is the current crop rectangle for this buffer slot.
Rect mCrop;
// mTransform is the current transform flags for this buffer slot.
uint32_t mTransform;
// mScalingMode is the current scaling mode for this buffer slot.
uint32_t mScalingMode;
// mTimestamp is the current timestamp for this buffer slot. This gets
// to set by queueBuffer each time this slot is queued.
int64_t mTimestamp;
// mFrameNumber is the number of the queued frame for this slot.
uint64_t mFrameNumber;
// mBuf is the slot index of this buffer
int mBuf;
// mFence is a fence that will signal when the buffer is idle.
sp<Fence> mFence;
// The following public functions is the consumer facing interface
// acquireBuffer attempts to acquire ownership of the next pending buffer in
// the BufferQueue. If no buffer is pending then it returns -EINVAL. If a
// buffer is successfully acquired, the information about the buffer is
// returned in BufferItem. If the buffer returned had previously been
// acquired then the BufferItem::mGraphicBuffer field of buffer is set to
// NULL and it is assumed that the consumer still holds a reference to the
// buffer.
status_t acquireBuffer(BufferItem *buffer);
// releaseBuffer releases a buffer slot from the consumer back to the
// BufferQueue pending a fence sync.
// If releaseBuffer returns STALE_BUFFER_SLOT, then the consumer must free
// any references to the just-released buffer that it might have, as if it
// had received a onBuffersReleased() call with a mask set for the released
// buffer.
// Note that the dependencies on EGL will be removed once we switch to using
// the Android HW Sync HAL.
status_t releaseBuffer(int buf, EGLDisplay display, EGLSyncKHR fence,
const sp<Fence>& releaseFence);
// consumerConnect connects a consumer to the BufferQueue. Only one
// consumer may be connected, and when that consumer disconnects the
// BufferQueue is placed into the "abandoned" state, causing most
// interactions with the BufferQueue by the producer to fail.
status_t consumerConnect(const sp<ConsumerListener>& consumer);
// consumerDisconnect 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 consumerDisconnect();
// getReleasedBuffers sets the value pointed to by slotMask to a bit mask
// indicating which buffer slots the have been released by the BufferQueue
// but have not yet been released by the consumer.
status_t getReleasedBuffers(uint32_t* slotMask);
// setDefaultBufferSize is used to set the size of buffers returned by
// requestBuffers when a with and height of zero is requested.
status_t setDefaultBufferSize(uint32_t w, uint32_t h);
// setDefaultBufferCount set the buffer count. If the client has requested
// a buffer count using setBufferCount, the server-buffer count will
// take effect once the client sets the count back to zero.
status_t setDefaultMaxBufferCount(int bufferCount);
// setMaxAcquiredBufferCount sets the maximum number of buffers that can
// be acquired by the consumer at one time. This call will fail if a
// producer is connected to the BufferQueue.
status_t setMaxAcquiredBufferCount(int maxAcquiredBuffers);
// isSynchronousMode returns whether the SurfaceTexture is currently in
// synchronous mode.
bool isSynchronousMode() const;
// setConsumerName sets the name used in logging
void setConsumerName(const String8& name);
// setDefaultBufferFormat allows the BufferQueue to create
// GraphicBuffers of a defaultFormat if no format is specified
// in dequeueBuffer
status_t setDefaultBufferFormat(uint32_t defaultFormat);
// setConsumerUsageBits will turn on additional usage bits for dequeueBuffer
status_t setConsumerUsageBits(uint32_t usage);
// setTransformHint bakes in rotation to buffers so overlays can be used
status_t setTransformHint(uint32_t hint);
// freeBufferLocked frees the resources (both GraphicBuffer and EGLImage)
// for the given slot.
void freeBufferLocked(int index);
// freeAllBuffersLocked frees the resources (both GraphicBuffer and
// EGLImage) for all slots.
void freeAllBuffersLocked();
// freeAllBuffersExceptHeadLocked frees the resources (both GraphicBuffer
// and EGLImage) for all slots except the head of mQueue
void freeAllBuffersExceptHeadLocked();
// drainQueueLocked drains the buffer queue if we're in synchronous mode
// returns immediately otherwise. It returns NO_INIT if the BufferQueue
// became abandoned or disconnected during this call.
status_t drainQueueLocked();
// drainQueueAndFreeBuffersLocked drains the buffer queue if we're in
// synchronous mode and free all buffers. In asynchronous mode, all buffers
// are freed except the current buffer.
status_t drainQueueAndFreeBuffersLocked();
// setDefaultMaxBufferCountLocked sets the maximum number of buffer slots
// that will be used if the producer does not override the buffer slot
// count.
status_t setDefaultMaxBufferCountLocked(int count);
// getMinBufferCountLocked returns the minimum number of buffers allowed
// given the current BufferQueue state.
int getMinMaxBufferCountLocked() const;
// getMinUndequeuedBufferCountLocked returns the minimum number of buffers
// that must remain in a state other than DEQUEUED.
int getMinUndequeuedBufferCountLocked() const;
// getMaxBufferCountLocked returns the maximum number of buffers that can
// be allocated at once. This value depends upon the following member
// variables:
// mSynchronousMode
// mMaxAcquiredBufferCount
// mDefaultMaxBufferCount
// mOverrideMaxBufferCount
// Any time one of these member variables is changed while a producer is
// connected, mDequeueCondition must be broadcast.
int getMaxBufferCountLocked() const;
struct BufferSlot {
: mEglDisplay(EGL_NO_DISPLAY),
mNeedsCleanupOnRelease(false) {
// mGraphicBuffer points to the buffer allocated for this slot or is NULL
// if no buffer has been allocated.
sp<GraphicBuffer> mGraphicBuffer;
// mEglDisplay is the EGLDisplay used to create mEglImage.
EGLDisplay mEglDisplay;
// BufferState represents the different states in which a buffer slot
// can be.
enum BufferState {
// FREE indicates that the buffer is not currently being used and
// will not be used in the future until it gets dequeued and
// subsequently queued by the client.
// aka "owned by BufferQueue, ready to be dequeued"
FREE = 0,
// DEQUEUED indicates that the buffer has been dequeued by the
// client, but has not yet been queued or canceled. The buffer is
// considered 'owned' by the client, and the server should not use
// it for anything.
// Note that when in synchronous-mode (mSynchronousMode == true),
// the buffer that's currently attached to the texture may be
// dequeued by the client. That means that the current buffer can
// be in either the DEQUEUED or QUEUED state. In asynchronous mode,
// however, the current buffer is always in the QUEUED state.
// aka "owned by producer, ready to be queued"
// QUEUED indicates that the buffer has been queued by the client,
// and has not since been made available for the client to dequeue.
// Attaching the buffer to the texture does NOT transition the
// buffer away from the QUEUED state. However, in Synchronous mode
// the current buffer may be dequeued by the client under some
// circumstances. See the note about the current buffer in the
// documentation for DEQUEUED.
// aka "owned by BufferQueue, ready to be acquired"
// aka "owned by consumer, ready to be released"
// mBufferState is the current state of this buffer slot.
BufferState mBufferState;
// mRequestBufferCalled is used for validating that the client did
// call requestBuffer() when told to do so. Technically this is not
// needed but useful for debugging and catching client bugs.
bool mRequestBufferCalled;
// mCrop is the current crop rectangle for this buffer slot.
Rect mCrop;
// mTransform is the current transform flags for this buffer slot.
uint32_t mTransform;
// mScalingMode is the current scaling mode for this buffer slot.
uint32_t mScalingMode;
// mTimestamp is the current timestamp for this buffer slot. This gets
// to set by queueBuffer each time this slot is queued.
int64_t mTimestamp;
// mFrameNumber is the number of the queued frame for this slot.
uint64_t mFrameNumber;
// mEglFence is the EGL sync object that must signal before the buffer
// associated with this buffer slot may be dequeued. It is initialized
// to EGL_NO_SYNC_KHR when the buffer is created and (optionally, based
// on a compile-time option) set to a new sync object in updateTexImage.
EGLSyncKHR mEglFence;
// mFence is a fence which will signal when work initiated by the
// previous owner of the buffer is finished. When the buffer is FREE,
// the fence indicates when the consumer has finished reading
// from the buffer, or when the producer has finished writing if it
// called cancelBuffer after queueing some writes. When the buffer is
// QUEUED, it indicates when the producer has finished filling the
// buffer. When the buffer is DEQUEUED or ACQUIRED, the fence has been
// passed to the consumer or producer along with ownership of the
// buffer, and mFence is empty.
sp<Fence> mFence;
// Indicates whether this buffer has been seen by a consumer yet
bool mAcquireCalled;
// Indicates whether this buffer needs to be cleaned up by consumer
bool mNeedsCleanupOnRelease;
// mSlots is the array of buffer slots that must be mirrored on the client
// side. This allows buffer ownership to be transferred between the client
// and server without sending a GraphicBuffer over binder. The entire array
// is initialized to NULL at construction time, and buffers are allocated
// for a slot when requestBuffer is called with that slot's index.
BufferSlot mSlots[NUM_BUFFER_SLOTS];
// mDefaultWidth holds the default width of allocated buffers. It is used
// in requestBuffers() if a width and height of zero is specified.
uint32_t mDefaultWidth;
// mDefaultHeight holds the default height of allocated buffers. It is used
// in requestBuffers() if a width and height of zero is specified.
uint32_t mDefaultHeight;
// mMaxAcquiredBufferCount is the number of buffers that the consumer may
// acquire at one time. It defaults to 1 and can be changed by the
// consumer via the setMaxAcquiredBufferCount method, but this may only be
// done when no producer is connected to the BufferQueue.
// This value is used to derive the value returned for the
// MIN_UNDEQUEUED_BUFFERS query by the producer.
int mMaxAcquiredBufferCount;
// mDefaultMaxBufferCount is the default limit on the number of buffers
// that will be allocated at one time. This default limit is set by the
// consumer. The limit (as opposed to the default limit) may be
// overridden by the producer.
int mDefaultMaxBufferCount;
// mOverrideMaxBufferCount is the limit on the number of buffers that will
// be allocated at one time. This value is set by the image producer by
// calling setBufferCount. The default is zero, which means the producer
// doesn't care about the number of buffers in the pool. In that case
// mDefaultMaxBufferCount is used as the limit.
int mOverrideMaxBufferCount;
// mGraphicBufferAlloc is the connection to SurfaceFlinger that is used to
// allocate new GraphicBuffer objects.
sp<IGraphicBufferAlloc> mGraphicBufferAlloc;
// mConsumerListener is used to notify the connected consumer of
// asynchronous events that it may wish to react to. It is initially set
// to NULL and is written by consumerConnect and consumerDisconnect.
sp<ConsumerListener> mConsumerListener;
// mSynchronousMode whether we're in synchronous mode or not
bool mSynchronousMode;
// mAllowSynchronousMode whether we allow synchronous mode or not
const bool mAllowSynchronousMode;
// mConnectedApi indicates the API that is currently connected to this
// BufferQueue. It defaults to NO_CONNECTED_API (= 0), and gets updated
// by the connect and disconnect methods.
int mConnectedApi;
// mDequeueCondition condition used for dequeueBuffer in synchronous mode
mutable Condition mDequeueCondition;
// mQueue is a FIFO of queued buffers used in synchronous mode
typedef Vector<int> Fifo;
Fifo mQueue;
// 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 ISurfaceTexture methods capable of returning an error.
bool mAbandoned;
// mName is a string used to identify the BufferQueue in log messages.
// It is set by the setName method.
String8 mConsumerName;
// mMutex is the mutex used to prevent concurrent access to the member
// variables of BufferQueue objects. It must be locked whenever the
// member variables are accessed.
mutable Mutex mMutex;
// mFrameCounter is the free running counter, incremented for every buffer queued
// with the surface Texture.
uint64_t mFrameCounter;
// mBufferHasBeenQueued is true once a buffer has been queued. It is reset
// by changing the buffer count.
bool mBufferHasBeenQueued;
// mDefaultBufferFormat can be set so it will override
// the buffer format when it isn't specified in dequeueBuffer
uint32_t mDefaultBufferFormat;
// mConsumerUsageBits contains flags the consumer wants for GraphicBuffers
uint32_t mConsumerUsageBits;
// mTransformHint is used to optimize for screen rotations
uint32_t mTransformHint;
// ----------------------------------------------------------------------------
}; // namespace android