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      1 /*
      2  * Copyright (C) 2009 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 MEDIA_BUFFER_GROUP_H_
     18 
     19 #define MEDIA_BUFFER_GROUP_H_
     20 
     21 #include <media/stagefright/MediaBuffer.h>
     22 #include <utils/Errors.h>
     23 #include <utils/threads.h>
     24 
     25 namespace android {
     26 
     27 class MediaBuffer;
     28 class MetaData;
     29 
     30 class MediaBufferGroup : public MediaBufferObserver {
     31 public:
     32     MediaBufferGroup(size_t growthLimit = 0);
     33 
     34     // create a media buffer group with preallocated buffers
     35     MediaBufferGroup(size_t buffers, size_t buffer_size, size_t growthLimit = 0);
     36 
     37     ~MediaBufferGroup();
     38 
     39     void add_buffer(MediaBuffer *buffer);
     40 
     41     bool has_buffers();
     42 
     43     // If nonBlocking is false, it blocks until a buffer is available and
     44     // passes it to the caller in *buffer, while returning OK.
     45     // The returned buffer will have a reference count of 1.
     46     // If nonBlocking is true and a buffer is not immediately available,
     47     // buffer is set to NULL and it returns WOULD_BLOCK.
     48     // If requestedSize is 0, any free MediaBuffer will be returned.
     49     // If requestedSize is > 0, the returned MediaBuffer should have buffer
     50     // size of at least requstedSize.
     51     status_t acquire_buffer(
     52             MediaBuffer **buffer, bool nonBlocking = false, size_t requestedSize = 0);
     53 
     54     size_t buffers() const { return mBuffers.size(); }
     55 
     56     // freeBuffers is the number of free buffers allowed to remain.
     57     void gc(size_t freeBuffers = 0);
     58 
     59 protected:
     60     virtual void signalBufferReturned(MediaBuffer *buffer);
     61 
     62 private:
     63     friend class MediaBuffer;
     64 
     65     Mutex mLock;
     66     Condition mCondition;
     67     size_t mGrowthLimit;  // Do not automatically grow group larger than this.
     68     std::list<MediaBuffer *> mBuffers;
     69 
     70     MediaBufferGroup(const MediaBufferGroup &);
     71     MediaBufferGroup &operator=(const MediaBufferGroup &);
     72 };
     73 
     74 }  // namespace android
     75 
     76 #endif  // MEDIA_BUFFER_GROUP_H_
     77