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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 <binder/IBinder.h>
#include <gui/IConsumerListener.h>
#include <gui/IGraphicBufferAlloc.h>
#include <gui/IGraphicBufferProducer.h>
#include <gui/IGraphicBufferConsumer.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 BnGraphicBufferProducer,
public BnGraphicBufferConsumer,
private IBinder::DeathRecipient {
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.
// for backward source compatibility
typedef ::android::ConsumerListener ConsumerListener;
// 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 BnConsumerListener {
ProxyConsumerListener(const wp<ConsumerListener>& consumerListener);
virtual ~ProxyConsumerListener();
virtual void onFrameAvailable();
virtual void onBuffersReleased();
// mConsumerListener is a weak reference to the IConsumerListener. This is
// the raison d'etre of ProxyConsumerListener.
wp<ConsumerListener> mConsumerListener;
// BufferQueue manages a pool of gralloc memory slots to be used by
// producers and consumers. allocator is used to allocate all the
// needed gralloc buffers.
BufferQueue(const sp<IGraphicBufferAlloc>& allocator = NULL);
virtual ~BufferQueue();
* IBinder::DeathRecipient interface
virtual void binderDied(const wp<IBinder>& who);
* IGraphicBufferProducer interface
// Query native window attributes. The "what" values are enumerated in
// window.h (e.g. NATIVE_WINDOW_FORMAT).
virtual int query(int what, int* value);
// setBufferCount updates the number of available buffer slots. If this
// method succeeds, buffer slots will be both unallocated and owned by
// the BufferQueue object (i.e. they are not owned by the producer or
// consumer).
// This will fail if the producer has dequeued any buffers, or if
// bufferCount is invalid. bufferCount must generally be a value
// between the minimum undequeued buffer count and NUM_BUFFER_SLOTS
// (inclusive). It may also be set to zero (the default) to indicate
// that the producer does not wish to set a value. The minimum value
// can be obtained by calling query(NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS,
// ...).
// This may only be called by the producer. The consumer will be told
// to discard buffers through the onBuffersReleased callback.
virtual status_t setBufferCount(int bufferCount);
// requestBuffer returns the GraphicBuffer for slot N.
// In normal operation, this is called the first time slot N is returned
// by dequeueBuffer. It must be called again if dequeueBuffer returns
// flags indicating that previously-returned buffers are no longer valid.
virtual status_t requestBuffer(int slot, sp<GraphicBuffer>* buf);
// dequeueBuffer gets the next buffer slot index for the producer 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 Fence::NO_FENCE, 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. If width and height are both zero, the
// default values specified by setDefaultBufferSize() are used instead.
// The pixel formats are enumerated in graphics.h, e.g.
// HAL_PIXEL_FORMAT_RGBA_8888. If the format is 0, the default format
// will be used.
// The usage argument specifies gralloc buffer usage flags. The values
// are enumerated in gralloc.h, e.g. GRALLOC_USAGE_HW_RENDER. These
// will be merged with the usage flags specified by setConsumerUsageBits.
// The return value may be a negative error value or a non-negative
// collection of flags. If the flags are set, the return values are
// valid, but additional actions must be performed.
// If IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION is set, the
// producer must discard cached GraphicBuffer references for the slot
// returned in buf.
// If IGraphicBufferProducer::RELEASE_ALL_BUFFERS is set, the producer
// must discard cached GraphicBuffer references for all slots.
// In both cases, the producer will need to call requestBuffer to get a
// GraphicBuffer handle for the returned slot.
virtual status_t dequeueBuffer(int *buf, sp<Fence>* fence, bool async,
uint32_t width, uint32_t height, uint32_t format, uint32_t usage);
// queueBuffer returns a filled buffer to the BufferQueue.
// Additional data is provided in the QueueBufferInput struct. Notably,
// 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 producer-specific and should be documented by the
// producer.
// The caller may provide a fence that signals when all rendering
// operations have completed. Alternatively, NO_FENCE may be used,
// indicating that the buffer is ready immediately.
// Some values are returned in the output struct: the current settings
// for default width and height, the current transform hint, and the
// number of queued buffers.
virtual status_t queueBuffer(int buf,
const QueueBufferInput& input, QueueBufferOutput* output);
// cancelBuffer returns a dequeued buffer to the BufferQueue, but doesn't
// queue it for use by the consumer.
// The buffer will not be overwritten until the fence signals. The fence
// will usually be the one obtained from dequeueBuffer.
virtual void cancelBuffer(int buf, const sp<Fence>& fence);
// connect attempts to connect a producer API to the BufferQueue. This
// must be called before any other IGraphicBufferProducer methods are
// called except for getAllocator. A consumer must already be connected.
// This method will fail if connect was previously called on the
// BufferQueue and no corresponding disconnect call was made (i.e. if
// it's still connected to a producer).
// APIs are enumerated in window.h (e.g. NATIVE_WINDOW_API_CPU).
virtual status_t connect(const sp<IBinder>& token,
int api, bool producerControlledByApp, QueueBufferOutput* output);
// disconnect attempts to disconnect a producer API from the BufferQueue.
// Calling this method will cause any subsequent calls to other
// IGraphicBufferProducer 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 producer API.
virtual status_t disconnect(int api);
* IGraphicBufferConsumer 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.
// If presentWhen is nonzero, it indicates the time when the buffer will
// be displayed on screen. If the buffer's timestamp is farther in the
// future, the buffer won't be acquired, and PRESENT_LATER will be
// returned. The presentation time is in nanoseconds, and the time base
virtual status_t acquireBuffer(BufferItem *buffer, nsecs_t presentWhen);
// releaseBuffer releases a buffer slot from the consumer back to the
// BufferQueue. This may be done while the buffer's contents are still
// being accessed. The fence will signal when the buffer is no longer
// in use. frameNumber is used to indentify the exact buffer returned.
// 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.
virtual status_t releaseBuffer(int buf, uint64_t frameNumber,
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.
// controlledByApp indicates whether the consumer is controlled by
// the application.
// consumer may not be NULL.
virtual status_t consumerConnect(const sp<IConsumerListener>& consumer, bool controlledByApp);
// 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.
virtual status_t consumerDisconnect();
// getReleasedBuffers sets the value pointed to by slotMask to a bit mask
// indicating which buffer slots have been released by the BufferQueue
// but have not yet been released by the consumer.
// This should be called from the onBuffersReleased() callback.
virtual status_t getReleasedBuffers(uint32_t* slotMask);
// setDefaultBufferSize is used to set the size of buffers returned by
// dequeueBuffer when a width and height of zero is requested. Default
// is 1x1.
virtual status_t setDefaultBufferSize(uint32_t w, uint32_t h);
// setDefaultMaxBufferCount sets the default value for the maximum buffer
// count (the initial default is 2). If the producer has requested a
// buffer count using setBufferCount, the default buffer count will only
// take effect if the producer sets the count back to zero.
// The count must be between 2 and NUM_BUFFER_SLOTS, inclusive.
virtual status_t setDefaultMaxBufferCount(int bufferCount);
// disableAsyncBuffer disables the extra buffer used in async mode
// (when both producer and consumer have set their "isControlledByApp"
// flag) and has dequeueBuffer() return WOULD_BLOCK instead.
// This can only be called before consumerConnect().
virtual status_t disableAsyncBuffer();
// setMaxAcquiredBufferCount sets the maximum number of buffers that can
// be acquired by the consumer at one time (default 1). This call will
// fail if a producer is connected to the BufferQueue.
virtual status_t setMaxAcquiredBufferCount(int maxAcquiredBuffers);
// setConsumerName sets the name used in logging
virtual void setConsumerName(const String8& name);
// setDefaultBufferFormat allows the BufferQueue to create
// GraphicBuffers of a defaultFormat if no format is specified
// in dequeueBuffer. Formats are enumerated in graphics.h; the
// initial default is HAL_PIXEL_FORMAT_RGBA_8888.
virtual status_t setDefaultBufferFormat(uint32_t defaultFormat);
// setConsumerUsageBits will turn on additional usage bits for dequeueBuffer.
// These are merged with the bits passed to dequeueBuffer. The values are
// enumerated in gralloc.h, e.g. GRALLOC_USAGE_HW_RENDER; the default is 0.
virtual status_t setConsumerUsageBits(uint32_t usage);
// setTransformHint bakes in rotation to buffers so overlays can be used.
// The values are enumerated in window.h, e.g.
// NATIVE_WINDOW_TRANSFORM_ROT_90. The default is 0 (no transform).
virtual status_t setTransformHint(uint32_t hint);
// dump our state in a String
virtual void dump(String8& result, const char* prefix) const;
// freeBufferLocked frees the GraphicBuffer and sync resources for the
// given slot.
void freeBufferLocked(int index);
// freeAllBuffersLocked frees the GraphicBuffer and sync resources for
// all slots.
void freeAllBuffersLocked();
// setDefaultMaxBufferCountLocked sets the maximum number of buffer slots
// that will be used if the producer does not override the buffer slot
// count. The count must be between 2 and NUM_BUFFER_SLOTS, inclusive.
// The initial default is 2.
status_t setDefaultMaxBufferCountLocked(int count);
// getMinUndequeuedBufferCount returns the minimum number of buffers
// that must remain in a state other than DEQUEUED.
// The async parameter tells whether we're in asynchronous mode.
int getMinUndequeuedBufferCount(bool async) const;
// getMinBufferCountLocked returns the minimum number of buffers allowed
// given the current BufferQueue state.
// The async parameter tells whether we're in asynchronous mode.
int getMinMaxBufferCountLocked(bool async) const;
// getMaxBufferCountLocked returns the maximum number of buffers that can
// be allocated at once. This value depends upon the following member
// variables:
// mDequeueBufferCannotBlock
// mMaxAcquiredBufferCount
// mDefaultMaxBufferCount
// mOverrideMaxBufferCount
// async parameter
// Any time one of these member variables is changed while a producer is
// connected, mDequeueCondition must be broadcast.
int getMaxBufferCountLocked(bool async) const;
// stillTracking returns true iff the buffer item is still being tracked
// in one of the slots.
bool stillTracking(const BufferItem *item) 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 EGLSyncKHR objects.
EGLDisplay mEglDisplay;
// BufferState represents the different states in which a buffer slot
// can be. All slots are initially FREE.
enum BufferState {
// FREE indicates that the buffer is available to be dequeued
// by the producer. The buffer may be in use by the consumer for
// a finite time, so the buffer must not be modified until the
// associated fence is signaled.
// The slot is "owned" by BufferQueue. It transitions to DEQUEUED
// when dequeueBuffer is called.
FREE = 0,
// DEQUEUED indicates that the buffer has been dequeued by the
// producer, but has not yet been queued or canceled. The
// producer may modify the buffer's contents as soon as the
// associated ready fence is signaled.
// The slot is "owned" by the producer. It can transition to
// QUEUED (via queueBuffer) or back to FREE (via cancelBuffer).
// QUEUED indicates that the buffer has been filled by the
// producer and queued for use by the consumer. The buffer
// contents may continue to be modified for a finite time, so
// the contents must not be accessed until the associated fence
// is signaled.
// The slot is "owned" by BufferQueue. It can transition to
// ACQUIRED (via acquireBuffer) or to FREE (if another buffer is
// queued in asynchronous mode).
// ACQUIRED indicates that the buffer has been acquired by the
// consumer. As with QUEUED, the contents must not be accessed
// by the consumer until the fence is signaled.
// The slot is "owned" by the consumer. It transitions to FREE
// when releaseBuffer is called.
// mBufferState is the current state of this buffer slot.
BufferState mBufferState;
// mRequestBufferCalled is used for validating that the producer did
// call requestBuffer() when told to do so. Technically this is not
// needed but useful for debugging and catching producer bugs.
bool mRequestBufferCalled;
// mFrameNumber is the number of the queued frame for this slot. This
// is used to dequeue buffers in LRU order (useful because buffers
// may be released before their release fence is signaled).
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 may be set to a
// new sync object in releaseBuffer. (This is deprecated in favor of
// mFence, below.)
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 set to NO_FENCE.
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 the
// consumer. This is set when a buffer in ACQUIRED state is freed.
// It causes releaseBuffer to return STALE_BUFFER_SLOT.
bool mNeedsCleanupOnRelease;
// mSlots is the array of buffer slots that must be mirrored on the
// producer side. This allows buffer ownership to be transferred between
// the producer and consumer 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 dequeueBuffer() if a width and height of zero is specified.
uint32_t mDefaultWidth;
// mDefaultHeight holds the default height of allocated buffers. It is used
// in dequeueBuffer() 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<IConsumerListener> mConsumerListener;
// mConsumerControlledByApp whether the connected consumer is controlled by the
// application.
bool mConsumerControlledByApp;
// mDequeueBufferCannotBlock whether dequeueBuffer() isn't allowed to block.
// this flag is set during connect() when both consumer and producer are controlled
// by the application.
bool mDequeueBufferCannotBlock;
// mUseAsyncBuffer whether an extra buffer is used in async mode to prevent
// dequeueBuffer() from ever blocking.
bool mUseAsyncBuffer;
// mConnectedApi indicates the producer 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<BufferItem> Fifo;
Fifo mQueue;
// mAbandoned indicates that the BufferQueue will no longer be used to
// consume image buffers pushed to it using the IGraphicBufferProducer
// interface. It is initialized to false, and set to true in the
// consumerDisconnect method. A BufferQueue that has been abandoned will
// return the NO_INIT error from all IGraphicBufferProducer methods
// capable of returning an error.
bool mAbandoned;
// mConsumerName is a string used to identify the BufferQueue in log
// messages. It is set by the setConsumerName 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 on every
// successful queueBuffer call, and buffer allocation.
uint64_t mFrameCounter;
// mBufferHasBeenQueued is true once a buffer has been queued. It is
// reset when something causes all buffers to be freed (e.g. 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;
// mConnectedProducerToken is used to set a binder death notification on the producer
sp<IBinder> mConnectedProducerToken;
// ----------------------------------------------------------------------------
}; // namespace android