1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef MEDIA_BASE_SERIAL_RUNNER_H_
6#define MEDIA_BASE_SERIAL_RUNNER_H_
7
8#include <queue>
9
10#include "base/callback.h"
11#include "base/memory/ref_counted.h"
12#include "base/memory/scoped_ptr.h"
13#include "base/memory/weak_ptr.h"
14#include "media/base/media_export.h"
15#include "media/base/pipeline_status.h"
16
17namespace base {
18class MessageLoopProxy;
19}
20
21namespace media {
22
23// Runs a series of bound functions accepting Closures or PipelineStatusCB.
24// SerialRunner doesn't use regular Closure/PipelineStatusCBs as it late binds
25// the completion callback as the series progresses.
26class MEDIA_EXPORT SerialRunner {
27 public:
28  typedef base::Callback<void(const base::Closure&)> BoundClosure;
29  typedef base::Callback<void(const PipelineStatusCB&)> BoundPipelineStatusCB;
30
31  // Serial queue of bound functions to run.
32  class MEDIA_EXPORT Queue {
33   public:
34    Queue();
35    ~Queue();
36
37    void Push(const BoundClosure& bound_fn);
38    void Push(const BoundPipelineStatusCB& bound_fn);
39
40   private:
41    friend class SerialRunner;
42
43    BoundPipelineStatusCB Pop();
44    bool empty();
45
46    std::queue<BoundPipelineStatusCB> bound_fns_;
47  };
48
49  // Executes the bound functions in series, executing |done_cb| when finished.
50  //
51  // All bound functions are executed on the thread that Run() is called on,
52  // including |done_cb|.
53  //
54  // To eliminate an unnecessary posted task, the first function is executed
55  // immediately on the caller's stack. It is *strongly advised* to ensure
56  // the calling code does no more work after the call to Run().
57  //
58  // In all cases, |done_cb| is guaranteed to execute on a separate calling
59  // stack.
60  //
61  // Deleting the object will prevent execution of any unstarted bound
62  // functions, including |done_cb|.
63  static scoped_ptr<SerialRunner> Run(
64      const Queue& bound_fns, const PipelineStatusCB& done_cb);
65
66 private:
67  friend struct base::DefaultDeleter<SerialRunner>;
68
69  SerialRunner(const Queue& bound_fns, const PipelineStatusCB& done_cb);
70  ~SerialRunner();
71
72  void RunNextInSeries(PipelineStatus last_status);
73
74  base::WeakPtrFactory<SerialRunner> weak_this_;
75  scoped_refptr<base::MessageLoopProxy> message_loop_;
76  Queue bound_fns_;
77  PipelineStatusCB done_cb_;
78
79  DISALLOW_COPY_AND_ASSIGN(SerialRunner);
80};
81
82}  // namespace media
83
84#endif  // MEDIA_BASE_SERIAL_RUNNER_H_
85