extensions/common/one_shot_event.cc

   1 // Copyright 2013 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 "extensions/common/one_shot_event.h"
   6
   7 #include "base/callback.h"
   8 #include "base/lazy_instance.h"
   9 #include "base/location.h"
  10 #include "base/single_thread_task_runner.h"
  11 #include "base/task_runner.h"
  12 #include "base/thread_task_runner_handle.h"
  13 #include "base/time/time.h"
  14
  15 using base::SingleThreadTaskRunner;
  16
  17 namespace extensions {
  18
  19 struct OneShotEvent::TaskInfo {
  20   TaskInfo() {}
  21   TaskInfo(const tracked_objects::Location& from_here,
  22            const scoped_refptr<SingleThreadTaskRunner>& runner,
  23            const base::Closure& task,
  24            const base::TimeDelta& delay)
  25       : from_here(from_here), runner(runner), task(task), delay(delay) {
  26     CHECK(runner.get());  // Detect mistakes with a decent stack frame.
  27   }
  28   tracked_objects::Location from_here;
  29   scoped_refptr<SingleThreadTaskRunner> runner;
  30   base::Closure task;
  31   base::TimeDelta delay;
  32 };
  33
  34 OneShotEvent::OneShotEvent() : signaled_(false) {
  35   // It's acceptable to construct the OneShotEvent on one thread, but
  36   // immediately move it to another thread.
  37   thread_checker_.DetachFromThread();
  38 }
  39 OneShotEvent::OneShotEvent(bool signaled) : signaled_(signaled) {
  40   thread_checker_.DetachFromThread();
  41 }
  42 OneShotEvent::~OneShotEvent() {}
  43
  44 void OneShotEvent::Post(const tracked_objects::Location& from_here,
  45                         const base::Closure& task) const {
  46   PostImpl(from_here, task, base::ThreadTaskRunnerHandle::Get(),
  47            base::TimeDelta());
  48 }
  49
  50 void OneShotEvent::Post(
  51     const tracked_objects::Location& from_here,
  52     const base::Closure& task,
  53     const scoped_refptr<SingleThreadTaskRunner>& runner) const {
  54   PostImpl(from_here, task, runner, base::TimeDelta());
  55 }
  56
  57 void OneShotEvent::PostDelayed(const tracked_objects::Location& from_here,
  58                                const base::Closure& task,
  59                                const base::TimeDelta& delay) const {
  60   PostImpl(from_here, task, base::ThreadTaskRunnerHandle::Get(), delay);
  61 }
  62
  63 void OneShotEvent::Signal() {
  64   DCHECK(thread_checker_.CalledOnValidThread());
  65
  66   CHECK(!signaled_) << "Only call Signal once.";
  67
  68   signaled_ = true;
  69   // After this point, a call to Post() from one of the queued tasks
  70   // could proceed immediately, but the fact that this object is
  71   // single-threaded prevents that from being relevant.
  72
  73   // We could randomize tasks_ in debug mode in order to check that
  74   // the order doesn't matter...
  75   for (size_t i = 0; i < tasks_.size(); ++i) {
  76     const TaskInfo& task = tasks_[i];
  77     if (task.delay != base::TimeDelta())
  78       task.runner->PostDelayedTask(task.from_here, task.task, task.delay);
  79     else
  80       task.runner->PostTask(task.from_here, task.task);
  81   }
  82 }
  83
  84 void OneShotEvent::PostImpl(const tracked_objects::Location& from_here,
  85                             const base::Closure& task,
  86                             const scoped_refptr<SingleThreadTaskRunner>& runner,
  87                             const base::TimeDelta& delay) const {
  88   DCHECK(thread_checker_.CalledOnValidThread());
  89
  90   if (is_signaled()) {
  91     if (delay != base::TimeDelta())
  92       runner->PostDelayedTask(from_here, task, delay);
  93     else
  94       runner->PostTask(from_here, task);
  95   } else {
  96     tasks_.push_back(TaskInfo(from_here, runner, task, delay));
  97   }
  98 }
  99
 100 }  // namespace extensions