cc/base/delayed_unique_notifier.cc

   1 // Copyright 2014 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 "cc/base/delayed_unique_notifier.h"
   6
   7 #include "base/bind.h"
   8 #include "base/bind_helpers.h"
   9 #include "base/location.h"
  10 #include "base/sequenced_task_runner.h"
  11
  12 namespace cc {
  13
  14 DelayedUniqueNotifier::DelayedUniqueNotifier(
  15     base::SequencedTaskRunner* task_runner,
  16     const base::Closure& closure,
  17     const base::TimeDelta& delay)
  18     : task_runner_(task_runner),
  19       closure_(closure),
  20       delay_(delay),
  21       notification_pending_(false),
  22       weak_ptr_factory_(this) {
  23 }
  24
  25 DelayedUniqueNotifier::~DelayedUniqueNotifier() {
  26 }
  27
  28 void DelayedUniqueNotifier::Schedule() {
  29   if (notification_pending_) {
  30     next_notification_time_ = Now() + delay_;
  31     return;
  32   }
  33
  34   next_notification_time_ = Now() + delay_;
  35   task_runner_->PostDelayedTask(FROM_HERE,
  36                                 base::Bind(&DelayedUniqueNotifier::NotifyIfTime,
  37                                            weak_ptr_factory_.GetWeakPtr()),
  38                                 delay_);
  39   notification_pending_ = true;
  40 }
  41
  42 void DelayedUniqueNotifier::Cancel() {
  43   next_notification_time_ = base::TimeTicks();
  44 }
  45
  46 void DelayedUniqueNotifier::Shutdown() {
  47   // This function must destroy any weak ptrs since after being cancelled, this
  48   // class may be destroyed on another thread during compositor shutdown.
  49   weak_ptr_factory_.InvalidateWeakPtrs();
  50   // Deliberately leaves notification_pending_ = true forever so new tasks with
  51   // weak ptrs can not be created.
  52   notification_pending_ = true;
  53 }
  54
  55 bool DelayedUniqueNotifier::HasPendingNotification() const {
  56   return notification_pending_ && !next_notification_time_.is_null();
  57 }
  58
  59 base::TimeTicks DelayedUniqueNotifier::Now() const {
  60   return base::TimeTicks::Now();
  61 }
  62
  63 void DelayedUniqueNotifier::NotifyIfTime() {
  64   // If next notifiaction time is not valid, then this schedule was canceled.
  65   if (next_notification_time_.is_null()) {
  66     notification_pending_ = false;
  67     return;
  68   }
  69
  70   // If the notification was rescheduled or arrived too early for any other
  71   // reason, then post another task instead of running the callback.
  72   base::TimeTicks now = Now();
  73   if (next_notification_time_ > now) {
  74     task_runner_->PostDelayedTask(
  75         FROM_HERE,
  76         base::Bind(&DelayedUniqueNotifier::NotifyIfTime,
  77                    weak_ptr_factory_.GetWeakPtr()),
  78         next_notification_time_ - now);
  79     return;
  80   }
  81
  82   // Note the order here is important since closure might schedule another run.
  83   notification_pending_ = false;
  84   closure_.Run();
  85 }
  86
  87 }  // namespace cc