1/*
2 * Copyright 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_GUI_BUFFERQUEUEPRODUCER_H
18#define ANDROID_GUI_BUFFERQUEUEPRODUCER_H
19
20#include <gui/BufferQueueDefs.h>
21#include <gui/IGraphicBufferProducer.h>
22
23namespace android {
24
25class BufferSlot;
26
27class BufferQueueProducer : public BnGraphicBufferProducer,
28                            private IBinder::DeathRecipient {
29public:
30    friend class BufferQueue; // Needed to access binderDied
31
32    BufferQueueProducer(const sp<BufferQueueCore>& core);
33    virtual ~BufferQueueProducer();
34
35    // requestBuffer returns the GraphicBuffer for slot N.
36    //
37    // In normal operation, this is called the first time slot N is returned
38    // by dequeueBuffer.  It must be called again if dequeueBuffer returns
39    // flags indicating that previously-returned buffers are no longer valid.
40    virtual status_t requestBuffer(int slot, sp<GraphicBuffer>* buf);
41
42    // setBufferCount updates the number of available buffer slots.  If this
43    // method succeeds, buffer slots will be both unallocated and owned by
44    // the BufferQueue object (i.e. they are not owned by the producer or
45    // consumer).
46    //
47    // This will fail if the producer has dequeued any buffers, or if
48    // bufferCount is invalid.  bufferCount must generally be a value
49    // between the minimum undequeued buffer count (exclusive) and NUM_BUFFER_SLOTS
50    // (inclusive).  It may also be set to zero (the default) to indicate
51    // that the producer does not wish to set a value.  The minimum value
52    // can be obtained by calling query(NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS,
53    // ...).
54    //
55    // This may only be called by the producer.  The consumer will be told
56    // to discard buffers through the onBuffersReleased callback.
57    virtual status_t setBufferCount(int bufferCount);
58
59    // dequeueBuffer gets the next buffer slot index for the producer to use.
60    // If a buffer slot is available then that slot index is written to the
61    // location pointed to by the buf argument and a status of OK is returned.
62    // If no slot is available then a status of -EBUSY is returned and buf is
63    // unmodified.
64    //
65    // The outFence parameter will be updated to hold the fence associated with
66    // the buffer. The contents of the buffer must not be overwritten until the
67    // fence signals. If the fence is Fence::NO_FENCE, the buffer may be
68    // written immediately.
69    //
70    // The width and height parameters must be no greater than the minimum of
71    // GL_MAX_VIEWPORT_DIMS and GL_MAX_TEXTURE_SIZE (see: glGetIntegerv).
72    // An error due to invalid dimensions might not be reported until
73    // updateTexImage() is called.  If width and height are both zero, the
74    // default values specified by setDefaultBufferSize() are used instead.
75    //
76    // The pixel formats are enumerated in graphics.h, e.g.
77    // HAL_PIXEL_FORMAT_RGBA_8888.  If the format is 0, the default format
78    // will be used.
79    //
80    // The usage argument specifies gralloc buffer usage flags.  The values
81    // are enumerated in gralloc.h, e.g. GRALLOC_USAGE_HW_RENDER.  These
82    // will be merged with the usage flags specified by setConsumerUsageBits.
83    //
84    // The return value may be a negative error value or a non-negative
85    // collection of flags.  If the flags are set, the return values are
86    // valid, but additional actions must be performed.
87    //
88    // If IGraphicBufferProducer::BUFFER_NEEDS_REALLOCATION is set, the
89    // producer must discard cached GraphicBuffer references for the slot
90    // returned in buf.
91    // If IGraphicBufferProducer::RELEASE_ALL_BUFFERS is set, the producer
92    // must discard cached GraphicBuffer references for all slots.
93    //
94    // In both cases, the producer will need to call requestBuffer to get a
95    // GraphicBuffer handle for the returned slot.
96    virtual status_t dequeueBuffer(int *outSlot, sp<Fence>* outFence, bool async,
97            uint32_t width, uint32_t height, uint32_t format, uint32_t usage);
98
99    // See IGraphicBufferProducer::detachBuffer
100    virtual status_t detachBuffer(int slot);
101
102    // See IGraphicBufferProducer::detachNextBuffer
103    virtual status_t detachNextBuffer(sp<GraphicBuffer>* outBuffer,
104            sp<Fence>* outFence);
105
106    // See IGraphicBufferProducer::attachBuffer
107    virtual status_t attachBuffer(int* outSlot, const sp<GraphicBuffer>& buffer);
108
109    // queueBuffer returns a filled buffer to the BufferQueue.
110    //
111    // Additional data is provided in the QueueBufferInput struct.  Notably,
112    // a timestamp must be provided for the buffer. The timestamp is in
113    // nanoseconds, and must be monotonically increasing. Its other semantics
114    // (zero point, etc) are producer-specific and should be documented by the
115    // producer.
116    //
117    // The caller may provide a fence that signals when all rendering
118    // operations have completed.  Alternatively, NO_FENCE may be used,
119    // indicating that the buffer is ready immediately.
120    //
121    // Some values are returned in the output struct: the current settings
122    // for default width and height, the current transform hint, and the
123    // number of queued buffers.
124    virtual status_t queueBuffer(int slot,
125            const QueueBufferInput& input, QueueBufferOutput* output);
126
127    // cancelBuffer returns a dequeued buffer to the BufferQueue, but doesn't
128    // queue it for use by the consumer.
129    //
130    // The buffer will not be overwritten until the fence signals.  The fence
131    // will usually be the one obtained from dequeueBuffer.
132    virtual void cancelBuffer(int slot, const sp<Fence>& fence);
133
134    // Query native window attributes.  The "what" values are enumerated in
135    // window.h (e.g. NATIVE_WINDOW_FORMAT).
136    virtual int query(int what, int* outValue);
137
138    // connect attempts to connect a producer API to the BufferQueue.  This
139    // must be called before any other IGraphicBufferProducer methods are
140    // called except for getAllocator.  A consumer must already be connected.
141    //
142    // This method will fail if connect was previously called on the
143    // BufferQueue and no corresponding disconnect call was made (i.e. if
144    // it's still connected to a producer).
145    //
146    // APIs are enumerated in window.h (e.g. NATIVE_WINDOW_API_CPU).
147    virtual status_t connect(const sp<IProducerListener>& listener,
148            int api, bool producerControlledByApp, QueueBufferOutput* output);
149
150    // disconnect attempts to disconnect a producer API from the BufferQueue.
151    // Calling this method will cause any subsequent calls to other
152    // IGraphicBufferProducer methods to fail except for getAllocator and connect.
153    // Successfully calling connect after this will allow the other methods to
154    // succeed again.
155    //
156    // This method will fail if the the BufferQueue is not currently
157    // connected to the specified producer API.
158    virtual status_t disconnect(int api);
159
160    // Attaches a sideband buffer stream to the IGraphicBufferProducer.
161    //
162    // A sideband stream is a device-specific mechanism for passing buffers
163    // from the producer to the consumer without using dequeueBuffer/
164    // queueBuffer. If a sideband stream is present, the consumer can choose
165    // whether to acquire buffers from the sideband stream or from the queued
166    // buffers.
167    //
168    // Passing NULL or a different stream handle will detach the previous
169    // handle if any.
170    virtual status_t setSidebandStream(const sp<NativeHandle>& stream);
171
172    // See IGraphicBufferProducer::allocateBuffers
173    virtual void allocateBuffers(bool async, uint32_t width, uint32_t height,
174            uint32_t format, uint32_t usage);
175
176private:
177    // This is required by the IBinder::DeathRecipient interface
178    virtual void binderDied(const wp<IBinder>& who);
179
180    // waitForFreeSlotThenRelock finds the oldest slot in the FREE state. It may
181    // block if there are no available slots and we are not in non-blocking
182    // mode (producer and consumer controlled by the application). If it blocks,
183    // it will release mCore->mMutex while blocked so that other operations on
184    // the BufferQueue may succeed.
185    status_t waitForFreeSlotThenRelock(const char* caller, bool async,
186            int* found, status_t* returnFlags) const;
187
188    sp<BufferQueueCore> mCore;
189
190    // This references mCore->mSlots. Lock mCore->mMutex while accessing.
191    BufferQueueDefs::SlotsType& mSlots;
192
193    // This is a cached copy of the name stored in the BufferQueueCore.
194    // It's updated during connect and dequeueBuffer (which should catch
195    // most updates).
196    String8 mConsumerName;
197
198    uint32_t mStickyTransform;
199
200    // This saves the fence from the last queueBuffer, such that the
201    // next queueBuffer call can throttle buffer production. The prior
202    // queueBuffer's fence is not nessessarily available elsewhere,
203    // since the previous buffer might have already been acquired.
204    sp<Fence> mLastQueueBufferFence;
205
206    // Take-a-ticket system for ensuring that onFrame* callbacks are called in
207    // the order that frames are queued. While the BufferQueue lock
208    // (mCore->mMutex) is held, a ticket is retained by the producer. After
209    // dropping the BufferQueue lock, the producer must wait on the condition
210    // variable until the current callback ticket matches its retained ticket.
211    Mutex mCallbackMutex;
212    int mNextCallbackTicket; // Protected by mCore->mMutex
213    int mCurrentCallbackTicket; // Protected by mCallbackMutex
214    Condition mCallbackCondition;
215
216}; // class BufferQueueProducer
217
218} // namespace android
219
220#endif
221