Implementation of MediaCodecPlayer stage 1

media/base/android/access_unit_queue.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MEDIA_BASE_ANDROID_ACCESS_UNIT_QUEUE_H_
+#define MEDIA_BASE_ANDROID_ACCESS_UNIT_QUEUE_H_
+
+#include <list>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
+#include "media/base/android/demuxer_stream_player_params.h"
+
+namespace media {
+
+// The queue of incoming data for MediaCodecDecoder.
+//
+// The data comes in the form of access units. Each access unit has a type,
+// if the type is |kConfigChanged| the access unit itself has no data, but
+// is accompanied with DemuxerConfigs.
+// The queue is accessed on the Media thread that puts the incoming data in and
+// the Decoder thread that gets the next access unit and eventually removes it
+// from the queue.
+class AccessUnitQueue {
+ public:
+  // Information about the queue state and the access unit at the front.
+  struct Info {
+    // The unit at front. Null if the queue is empty.
+    const AccessUnit* front_unit;
+
+    // Configs for the front unit if it is |kConfigChanged|, null otherwise.
+    const DemuxerConfigs* configs;
+
+    // Number of access units in the queue.
+    int length;
+
+    // Whether the queue contains End Of Stream.
+    bool has_eos;
+
+    Info()
+        : front_unit(nullptr), configs(nullptr), length(0), has_eos(false) {}
+  };
+
+  AccessUnitQueue();
+  ~AccessUnitQueue();
+
+  // Appends the incoming data to the queue.
+  void PushBack(const DemuxerData& frames);
+
+  // Advances the front position to next unit. Logically the preceding units

[watk, 2015/06/04 20:56:43]

s/units/unit

[Tima Vaisburd, 2015/06/05 04:17:46]

Actually s/does/do because there could be several units preceding the front one.
Anyway, done.

+  // does not exist, but they can be physically removed later.
+  void Advance();
+
+  // Clears the queue.
+  void Flush();
+
+  // Looks back for the first key frame and if it exists, sets the current
+  // access unit to it and returns true. Otherwise returns false.
+  bool SkipToKeyFrame();
+
+  // Returns the information about the queue.
+  void GetInfo(Info* info) const;
+
+  // For unit tests only.
+  size_t NumChunksForTesting() const { return chunks_.size(); }
+
+ private:
+  // Returns the amount of access units that has not been passed to decoder yet.
+  int GetUndecodedAccessUnitLength() const;
+
+  // The queue of data chunks.
+  typedef std::list< scoped_ptr<DemuxerData> > DataChunkQueue;

[watk, 2015/06/04 20:56:43]

Spaces around the template param is unconventional I think. clang format removes
these spaces.

[Tima Vaisburd, 2015/06/05 04:17:46]

Done.

+  DataChunkQueue chunks_;
+
+  // The chunk that contains the current access unit.
+  DataChunkQueue::iterator current_chunk_;
+
+  // Index of the current access unit within the current chunk.
+  size_t index_in_chunk_;
+
+  // Indicates that a unit with End Of Stream flag has been appended.
+  bool has_eos_;
+
+  // The queue works on two threads.

[watk, 2015/06/04 20:56:43]

I suggest saying instead what the lock protects.

[Tima Vaisburd, 2015/06/05 04:17:46]

Wrote "The lock protects all fields together".

+  mutable base::Lock lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(AccessUnitQueue);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_ANDROID_ACCESS_UNIT_QUEUE_H_