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 /*

  * Copyright (C) 2012 The Android Open Source Project

  * Copyright (C) 2013 Mozilla Foundation

  *

  * 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 NATIVEWINDOW_GONKBUFFERQUEUE_JB_H

 #define NATIVEWINDOW_GONKBUFFERQUEUE_JB_H

 #include <gui/IGraphicBufferAlloc.h>

 #if ANDROID_VERSION == 17

 #include <gui/ISurfaceTexture.h>

 #else

 #include <gui/IGraphicBufferProducer.h>

 #endif

 #include <ui/Fence.h>

 #include <ui/GraphicBuffer.h>

 #include <utils/String8.h>

 #include <utils/Vector.h>

 #include <utils/threads.h>

 #include "mozilla/layers/LayersSurfaces.h"

 #include "mozilla/layers/TextureClient.h"

 #if ANDROID_VERSION == 17

 #define IGraphicBufferProducer ISurfaceTexture

 #endif

 namespace android {

 // ----------------------------------------------------------------------------

 #if ANDROID_VERSION == 17

 class GonkBufferQueue : public BnSurfaceTexture {

 #else

 class GonkBufferQueue : public BnGraphicBufferProducer {

 #endif

     typedef mozilla::layers::TextureClient TextureClient;

 public:

     enum { MIN_UNDEQUEUED_BUFFERS = 2 };

     enum { NUM_BUFFER_SLOTS = 32 };

     enum { NO_CONNECTED_API = 0 };

     enum { INVALID_BUFFER_SLOT = -1 };

     enum { STALE_BUFFER_SLOT = 1, NO_BUFFER_AVAILABLE };

     // When in async mode we reserve two slots in order to guarantee that the

     // producer and consumer can run asynchronously.

     enum { MAX_MAX_ACQUIRED_BUFFERS = NUM_BUFFER_SLOTS - 2 };

     // ConsumerListener is the interface through which the GonkBufferQueue 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

     // the consumer to the GonkBufferQueue, these calls from the GonkBufferQueue to the

     // consumer *MUST* be called only when the GonkBufferQueue 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

         // GonkBufferQueue has released its references to one or more GraphicBuffers

         // contained in its slots.  The buffer consumer should then call

         // GonkBufferQueue::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

     // GonkBufferQueue object and the consumer object.  The reason this can't be a weak

     // reference in the GonkBufferQueue class is because we're planning to expose the

     // consumer side of a GonkBufferQueue as a binder interface, which doesn't support

     // weak references.

     class ProxyConsumerListener : public GonkBufferQueue::ConsumerListener {

     public:

         ProxyConsumerListener(const wp<GonkBufferQueue::ConsumerListener>& consumerListener);

         virtual ~ProxyConsumerListener();

         virtual void onFrameAvailable();

         virtual void onBuffersReleased();

     private:

         // mConsumerListener is a weak reference to the ConsumerListener.  This is

         // the raison d'etre of ProxyConsumerListener.

         wp<GonkBufferQueue::ConsumerListener> mConsumerListener;

     };

     // GonkBufferQueue 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.

     GonkBufferQueue(bool allowSynchronousMode = true,

             const sp<IGraphicBufferAlloc>& allocator = NULL);

     virtual ~GonkBufferQueue();

     // 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 GonkBufferQueue 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

     // GL_MAX_VIEWPORT_DIMS and GL_MAX_TEXTURE_SIZE (see: glGetIntegerv).

     // 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.

 #if ANDROID_VERSION == 17

     virtual status_t dequeueBuffer(int *buf, sp<Fence>& fence,

             uint32_t width, uint32_t height, uint32_t format, uint32_t usage) {

         return dequeueBuffer(buf, &fence, width, height, format, usage);

     }

 #endif

     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 GonkBufferQueue.

     //

     // 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 GonkBufferQueue, 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.

 #if ANDROID_VERSION == 17

     virtual void cancelBuffer(int buf, sp<Fence> fence);

 #else

     virtual void cancelBuffer(int buf, const sp<Fence>& fence);

 #endif

     // setSynchronousMode sets 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 acquired in order.  In asynchronous mode,

     // a queued buffer may be replaced by a subsequently queued buffer.

     //

     // The default mode is asynchronous.

     virtual status_t setSynchronousMode(bool enabled);

     // connect attempts to connect a producer API to the GonkBufferQueue.  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

     // GonkBufferQueue 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(int api, QueueBufferOutput* output);

     // disconnect attempts to disconnect a producer API from the GonkBufferQueue.

     // 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 GonkBufferQueue is not currently

     // connected to the specified producer 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 {

         BufferItem()

          :

            mTransform(0),

            mScalingMode(NATIVE_WINDOW_SCALING_MODE_FREEZE),

            mTimestamp(0),

            mFrameNumber(0),

            mBuf(INVALID_BUFFER_SLOT) {

              mCrop.makeInvalid();

         }

         // mGraphicBuffer points to the buffer allocated for this slot, or is NULL

         // if the buffer in this slot has been acquired in the past (see

         // BufferSlot.mAcquireCalled).

         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 are the consumer-facing interface

     // acquireBuffer attempts to acquire ownership of the next pending buffer in

     // the GonkBufferQueue.  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

     // GonkBufferQueue.  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.

     //

     // 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, const sp<Fence>& releaseFence);

     // consumerConnect connects a consumer to the GonkBufferQueue.  Only one

     // consumer may be connected, and when that consumer disconnects the

     // GonkBufferQueue is placed into the "abandoned" state, causing most

     // interactions with the GonkBufferQueue by the producer to fail.

     //

     // consumer may not be NULL.

     status_t consumerConnect(const sp<ConsumerListener>& consumer);

     // consumerDisconnect disconnects a consumer from the GonkBufferQueue. All

     // buffers will be freed and the GonkBufferQueue is placed in the "abandoned"

     // state, causing most interactions with the GonkBufferQueue by the producer to

     // fail.

     status_t consumerDisconnect();

     // getReleasedBuffers sets the value pointed to by slotMask to a bit mask

     // indicating which buffer slots have been released by the GonkBufferQueue

     // but have not yet been released by the consumer.

     //

     // This should be called from the onBuffersReleased() callback.

     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.

     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.

     status_t setDefaultMaxBufferCount(int bufferCount);

     // 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 GonkBufferQueue.

     status_t setMaxAcquiredBufferCount(int maxAcquiredBuffers);

     // isSynchronousMode returns whether the GonkBufferQueue is currently in

     // synchronous mode.

     bool isSynchronousMode() const;

     // setConsumerName sets the name used in logging

     void setConsumerName(const String8& name);

     // setDefaultBufferFormat allows the GonkBufferQueue 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.

     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.

     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).

     status_t setTransformHint(uint32_t hint);

     mozilla::TemporaryRef<TextureClient> getTextureClientFromBuffer(ANativeWindowBuffer* buffer);

     int getSlotFromTextureClientLocked(TextureClient* client) const;

 private:

     // 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();

     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);

     // getMinBufferCountLocked returns the minimum number of buffers allowed

     // given the current GonkBufferQueue 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 {

         BufferSlot()

         : mBufferState(BufferSlot::FREE),

           mRequestBufferCalled(false),

           mTransform(0),

           mScalingMode(NATIVE_WINDOW_SCALING_MODE_FREEZE),

           mTimestamp(0),

           mFrameNumber(0),

           mAcquireCalled(false),

           mNeedsCleanupOnRelease(false) {

             mCrop.makeInvalid();

         }

         // mGraphicBuffer points to the buffer allocated for this slot or is NULL

         // if no buffer has been allocated.

         sp<GraphicBuffer> mGraphicBuffer;

         // mTextureClient is a thin abstraction over remotely allocated GraphicBuffer.

         mozilla::RefPtr<TextureClient> mTextureClient;

         // 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 GonkBufferQueue.  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).

             DEQUEUED = 1,

             // 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 GonkBufferQueue.  It can transition to

             // ACQUIRED (via acquireBuffer) or to FREE (if another buffer is

             // queued in asynchronous mode).

             QUEUED = 2,

             // 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.

             ACQUIRED = 3

         };

         // 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;

         // mCrop is the current crop rectangle for this buffer slot.

         Rect mCrop;

         // mTransform is the current transform flags for this buffer slot.

         // (example: NATIVE_WINDOW_TRANSFORM_ROT_90)

         uint32_t mTransform;

         // mScalingMode is the current scaling mode for this buffer slot.

         // (example: NATIVE_WINDOW_SCALING_MODE_FREEZE)

         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.  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 GonkBufferQueue.

     //

     // 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.  Set

     // when the GonkBufferQueue is created (by the consumer).

     const bool mAllowSynchronousMode;

     // mConnectedApi indicates the producer API that is currently connected

     // to this GonkBufferQueue.  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 GonkBufferQueue 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 GonkBufferQueue 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 GonkBufferQueue 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 GonkBufferQueue 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.

     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;

 };

 // ----------------------------------------------------------------------------

 }; // namespace android

 #endif // ANDROID_GUI_BUFFERQUEUE_H