storage/browser/fileapi/timed_task_helper.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 "storage/browser/fileapi/timed_task_helper.h"
   6
   7 #include "base/bind.h"
   8 #include "base/logging.h"
   9 #include "base/sequenced_task_runner.h"
  10
  11 namespace storage {
  12
  13 struct TimedTaskHelper::Tracker {
  14   explicit Tracker(TimedTaskHelper* timer) : timer(timer) {}
  15
  16   ~Tracker() {
  17     if (timer)
  18       timer->tracker_ = NULL;
  19   }
  20
  21   TimedTaskHelper* timer;
  22 };
  23
  24 TimedTaskHelper::TimedTaskHelper(base::SequencedTaskRunner* task_runner)
  25     : task_runner_(task_runner),
  26       tracker_(NULL) {
  27 }
  28
  29 TimedTaskHelper::~TimedTaskHelper() {
  30   if (tracker_)
  31     tracker_->timer = NULL;
  32 }
  33
  34 bool TimedTaskHelper::IsRunning() const {
  35   DCHECK(task_runner_->RunsTasksOnCurrentThread());
  36   return tracker_ != NULL;
  37 }
  38
  39 void TimedTaskHelper::Start(
  40     const tracked_objects::Location& posted_from,
  41     base::TimeDelta delay,
  42     const base::Closure& user_task) {
  43   posted_from_ = posted_from;
  44   delay_ = delay;
  45   user_task_ = user_task;
  46   Reset();
  47 }
  48
  49 void TimedTaskHelper::Reset() {
  50   DCHECK(task_runner_->RunsTasksOnCurrentThread());
  51   DCHECK(!user_task_.is_null());
  52   desired_run_time_ = base::TimeTicks::Now() + delay_;
  53
  54   if (tracker_)
  55     return;
  56
  57   // Initialize the tracker for the first time.
  58   tracker_ = new Tracker(this);
  59   PostDelayedTask(make_scoped_ptr(tracker_), delay_);
  60 }
  61
  62 // static
  63 void TimedTaskHelper::Fired(scoped_ptr<Tracker> tracker) {
  64   if (!tracker->timer)
  65     return;
  66   TimedTaskHelper* timer = tracker->timer;
  67   timer->OnFired(tracker.Pass());
  68 }
  69
  70 void TimedTaskHelper::OnFired(scoped_ptr<Tracker> tracker) {
  71   DCHECK(task_runner_->RunsTasksOnCurrentThread());
  72   base::TimeTicks now = base::TimeTicks::Now();
  73   if (desired_run_time_ > now) {
  74     PostDelayedTask(tracker.Pass(), desired_run_time_ - now);
  75     return;
  76   }
  77   tracker.reset();
  78   base::Closure task = user_task_;
  79   user_task_.Reset();
  80   task.Run();
  81 }
  82
  83 void TimedTaskHelper::PostDelayedTask(scoped_ptr<Tracker> tracker,
  84                                       base::TimeDelta delay) {
  85   task_runner_->PostDelayedTask(
  86       posted_from_,
  87       base::Bind(&TimedTaskHelper::Fired, base::Passed(&tracker)),
  88       delay);
  89 }
  90
  91 }  // namespace storage