1 /* 2 * Copyright (C) 2013 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_RINGBUFFERCONSUMER_H 18 #define ANDROID_GUI_RINGBUFFERCONSUMER_H 19 20 #include <gui/ConsumerBase.h> 21 22 #include <ui/GraphicBuffer.h> 23 24 #include <utils/String8.h> 25 #include <utils/Vector.h> 26 #include <utils/threads.h> 27 #include <utils/List.h> 28 29 #define ANDROID_GRAPHICS_RINGBUFFERCONSUMER_JNI_ID "mRingBufferConsumer" 30 31 namespace android { 32 33 /** 34 * The RingBufferConsumer maintains a ring buffer of BufferItem objects, 35 * (which are 'acquired' as long as they are part of the ring buffer, and 36 * 'released' when they leave the ring buffer). 37 * 38 * When new buffers are produced, the oldest non-pinned buffer item is immediately 39 * dropped from the ring buffer, and overridden with the newest buffer. 40 * 41 * Users can only access a buffer item after pinning it (which also guarantees 42 * that during its duration it will not be released back into the BufferQueue). 43 * 44 * Note that the 'oldest' buffer is the one with the smallest timestamp. 45 * 46 * Edge cases: 47 * - If ringbuffer is not full, no drops occur when a buffer is produced. 48 * - If all the buffers get filled or pinned then there will be no empty 49 * buffers left, so the producer will block on dequeue. 50 */ 51 class RingBufferConsumer : public ConsumerBase, 52 public ConsumerBase::FrameAvailableListener 53 { 54 public: 55 typedef ConsumerBase::FrameAvailableListener FrameAvailableListener; 56 57 typedef BufferQueue::BufferItem BufferItem; 58 59 enum { INVALID_BUFFER_SLOT = BufferQueue::INVALID_BUFFER_SLOT }; 60 enum { NO_BUFFER_AVAILABLE = BufferQueue::NO_BUFFER_AVAILABLE }; 61 62 // Create a new ring buffer consumer. The consumerUsage parameter determines 63 // the consumer usage flags passed to the graphics allocator. The 64 // bufferCount parameter specifies how many buffers can be pinned for user 65 // access at the same time. 66 RingBufferConsumer(const sp<IGraphicBufferConsumer>& consumer, uint32_t consumerUsage, 67 int bufferCount); 68 69 virtual ~RingBufferConsumer(); 70 71 // set the name of the RingBufferConsumer that will be used to identify it in 72 // log messages. 73 void setName(const String8& name); 74 75 // setDefaultBufferSize is used to set the size of buffers returned by 76 // requestBuffers when a with and height of zero is requested. 77 status_t setDefaultBufferSize(uint32_t w, uint32_t h); 78 79 // setDefaultBufferFormat allows the BufferQueue to create 80 // GraphicBuffers of a defaultFormat if no format is specified 81 // by the producer endpoint. 82 status_t setDefaultBufferFormat(uint32_t defaultFormat); 83 84 // setConsumerUsage allows the BufferQueue consumer usage to be 85 // set at a later time after construction. 86 status_t setConsumerUsage(uint32_t usage); 87 88 // Buffer info, minus the graphics buffer/slot itself. 89 struct BufferInfo { 90 // mCrop is the current crop rectangle for this buffer slot. 91 Rect mCrop; 92 93 // mTransform is the current transform flags for this buffer slot. 94 uint32_t mTransform; 95 96 // mScalingMode is the current scaling mode for this buffer slot. 97 uint32_t mScalingMode; 98 99 // mTimestamp is the current timestamp for this buffer slot. This gets 100 // to set by queueBuffer each time this slot is queued. 101 int64_t mTimestamp; 102 103 // mFrameNumber is the number of the queued frame for this slot. 104 uint64_t mFrameNumber; 105 106 // mPinned is whether or not the buffer has been pinned already. 107 bool mPinned; 108 }; 109 110 struct RingBufferComparator { 111 // Return < 0 to select i1, > 0 to select i2, 0 for neither 112 // i1 or i2 can be NULL. 113 // 114 // The comparator has to implement a total ordering. Otherwise 115 // a linear scan won't find the most preferred buffer. 116 virtual int compare(const BufferInfo* i1, 117 const BufferInfo* i2) const = 0; 118 119 virtual ~RingBufferComparator() {} 120 }; 121 122 struct PinnedBufferItem : public LightRefBase<PinnedBufferItem> { 123 PinnedBufferItem(wp<RingBufferConsumer> consumer, 124 const BufferItem& item) : 125 mConsumer(consumer), 126 mBufferItem(item) { 127 } 128 129 ~PinnedBufferItem() { 130 sp<RingBufferConsumer> consumer = mConsumer.promote(); 131 if (consumer != NULL) { 132 consumer->unpinBuffer(mBufferItem); 133 } 134 } 135 136 bool isEmpty() { 137 return mBufferItem.mBuf == BufferQueue::INVALID_BUFFER_SLOT; 138 } 139 140 BufferItem& getBufferItem() { return mBufferItem; } 141 const BufferItem& getBufferItem() const { return mBufferItem; } 142 143 private: 144 wp<RingBufferConsumer> mConsumer; 145 BufferItem mBufferItem; 146 }; 147 148 // Find a buffer using the filter, then pin it before returning it. 149 // 150 // The filter will be invoked on each buffer item in the ring buffer, 151 // passing the item that was selected from each previous iteration, 152 // as well as the current iteration's item. 153 // 154 // Pinning will ensure that the buffer will not be dropped when a new 155 // frame is available. 156 sp<PinnedBufferItem> pinSelectedBuffer(const RingBufferComparator& filter, 157 bool waitForFence = true); 158 159 // Release all the non-pinned buffers in the ring buffer 160 status_t clear(); 161 162 // Return 0 if RingBuffer is empty, otherwise return timestamp of latest buffer. 163 nsecs_t getLatestTimestamp(); 164 165 private: 166 167 // Override ConsumerBase::onFrameAvailable 168 virtual void onFrameAvailable(); 169 170 void pinBufferLocked(const BufferItem& item); 171 void unpinBuffer(const BufferItem& item); 172 173 // Releases oldest buffer. Returns NO_BUFFER_AVAILABLE 174 // if all the buffers were pinned. 175 // Returns NOT_ENOUGH_DATA if list was empty. 176 status_t releaseOldestBufferLocked(size_t* pinnedFrames); 177 178 struct RingBufferItem : public BufferItem { 179 RingBufferItem() : BufferItem(), mPinCount(0) {} 180 int mPinCount; 181 }; 182 183 // List of acquired buffers in our ring buffer 184 List<RingBufferItem> mBufferItemList; 185 const int mBufferCount; 186 187 // Timestamp of latest buffer 188 nsecs_t mLatestTimestamp; 189 }; 190 191 } // namespace android 192 193 #endif // ANDROID_GUI_CPUCONSUMER_H 194