media/libstagefright/include/media/stagefright/MediaBufferGroup.h

/*
 * Copyright (C) 2009 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
 *
 *      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 MEDIA_BUFFER_GROUP_H_

#define MEDIA_BUFFER_GROUP_H_

#include <media/stagefright/MediaBuffer.h>
#include <utils/Errors.h>
#include <utils/threads.h>

namespace android {

class MediaBuffer;
class MetaData;

class MediaBufferGroup : public MediaBufferObserver {
public:
    MediaBufferGroup(size_t growthLimit = 0);

    // create a media buffer group with preallocated buffers
    MediaBufferGroup(size_t buffers, size_t buffer_size, size_t growthLimit = 0);

    ~MediaBufferGroup();

    void add_buffer(MediaBuffer *buffer);

    bool has_buffers();

    // If nonBlocking is false, it blocks until a buffer is available and
    // passes it to the caller in *buffer, while returning OK.
    // The returned buffer will have a reference count of 1.
    // If nonBlocking is true and a buffer is not immediately available,
    // buffer is set to NULL and it returns WOULD_BLOCK.
    // If requestedSize is 0, any free MediaBuffer will be returned.
    // If requestedSize is > 0, the returned MediaBuffer should have buffer
    // size of at least requstedSize.
    status_t acquire_buffer(
            MediaBuffer **buffer, bool nonBlocking = false, size_t requestedSize = 0);

    size_t buffers() const { return mBuffers.size(); }

    // If buffer is nullptr, have acquire_buffer() check for remote release.
    virtual void signalBufferReturned(MediaBuffer *buffer);

private:
    friend class MediaBuffer;

    Mutex mLock;
    Condition mCondition;
    size_t mGrowthLimit;  // Do not automatically grow group larger than this.
    std::list<MediaBuffer *> mBuffers;

    MediaBufferGroup(const MediaBufferGroup &);
    MediaBufferGroup &operator=(const MediaBufferGroup &);
};

}  // namespace android

#endif  // MEDIA_BUFFER_GROUP_H_