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#include "media/base/serial_runner.h"
6
7#include "base/bind.h"
8#include "base/callback_helpers.h"
9#include "base/location.h"
10#include "base/message_loop/message_loop_proxy.h"
11#include "base/single_thread_task_runner.h"
12
13namespace media {
14
15// Converts a Closure into a bound function accepting a PipelineStatusCB.
16static void RunClosure(
17    const base::Closure& closure,
18    const PipelineStatusCB& status_cb) {
19  closure.Run();
20  status_cb.Run(PIPELINE_OK);
21}
22
23// Converts a bound function accepting a Closure into a bound function
24// accepting a PipelineStatusCB. Since closures have no way of reporting a
25// status |status_cb| is executed with PIPELINE_OK.
26static void RunBoundClosure(
27    const SerialRunner::BoundClosure& bound_closure,
28    const PipelineStatusCB& status_cb) {
29  bound_closure.Run(base::Bind(status_cb, PIPELINE_OK));
30}
31
32// Runs |status_cb| with |last_status| on |task_runner|.
33static void RunOnTaskRunner(
34    const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
35    const PipelineStatusCB& status_cb,
36    PipelineStatus last_status) {
37  // Force post to permit cancellation of a series in the scenario where all
38  // bound functions run on the same thread.
39  task_runner->PostTask(FROM_HERE, base::Bind(status_cb, last_status));
40}
41
42SerialRunner::Queue::Queue() {}
43SerialRunner::Queue::~Queue() {}
44
45void SerialRunner::Queue::Push(const base::Closure& closure) {
46  bound_fns_.push(base::Bind(&RunClosure, closure));
47}
48
49void SerialRunner::Queue::Push(
50    const BoundClosure& bound_closure) {
51  bound_fns_.push(base::Bind(&RunBoundClosure, bound_closure));
52}
53
54void SerialRunner::Queue::Push(
55    const BoundPipelineStatusCB& bound_status_cb) {
56  bound_fns_.push(bound_status_cb);
57}
58
59SerialRunner::BoundPipelineStatusCB SerialRunner::Queue::Pop() {
60  BoundPipelineStatusCB bound_fn = bound_fns_.front();
61  bound_fns_.pop();
62  return bound_fn;
63}
64
65bool SerialRunner::Queue::empty() {
66  return bound_fns_.empty();
67}
68
69SerialRunner::SerialRunner(const Queue& bound_fns,
70                           const PipelineStatusCB& done_cb)
71    : task_runner_(base::MessageLoopProxy::current()),
72      bound_fns_(bound_fns),
73      done_cb_(done_cb),
74      weak_factory_(this) {
75  // Respect both cancellation and calling stack guarantees for |done_cb|
76  // when empty.
77  if (bound_fns_.empty()) {
78    task_runner_->PostTask(FROM_HERE,
79                           base::Bind(&SerialRunner::RunNextInSeries,
80                                      weak_factory_.GetWeakPtr(),
81                                      PIPELINE_OK));
82    return;
83  }
84
85  RunNextInSeries(PIPELINE_OK);
86}
87
88SerialRunner::~SerialRunner() {}
89
90scoped_ptr<SerialRunner> SerialRunner::Run(
91    const Queue& bound_fns, const PipelineStatusCB& done_cb) {
92  scoped_ptr<SerialRunner> callback_series(
93      new SerialRunner(bound_fns, done_cb));
94  return callback_series.Pass();
95}
96
97void SerialRunner::RunNextInSeries(PipelineStatus last_status) {
98  DCHECK(task_runner_->BelongsToCurrentThread());
99  DCHECK(!done_cb_.is_null());
100
101  if (bound_fns_.empty() || last_status != PIPELINE_OK) {
102    base::ResetAndReturn(&done_cb_).Run(last_status);
103    return;
104  }
105
106  BoundPipelineStatusCB bound_fn = bound_fns_.Pop();
107  bound_fn.Run(base::Bind(
108      &RunOnTaskRunner,
109      task_runner_,
110      base::Bind(&SerialRunner::RunNextInSeries, weak_factory_.GetWeakPtr())));
111}
112
113}  // namespace media
114