cc/base/delayed_unique_notifier.h

   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 #ifndef CC_BASE_DELAYED_UNIQUE_NOTIFIER_H_
   6 #define CC_BASE_DELAYED_UNIQUE_NOTIFIER_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/weak_ptr.h"
  10 #include "cc/base/cc_export.h"
  11
  12 namespace base {
  13 class SequencedTaskRunner;
  14 }  // namespace base
  15
  16 namespace cc {
  17
  18 class CC_EXPORT DelayedUniqueNotifier {
  19  public:
  20   // Configure this notifier to issue the |closure| notification in |delay| time
  21   // from Schedule() call.
  22   DelayedUniqueNotifier(base::SequencedTaskRunner* task_runner,
  23                         const base::Closure& closure,
  24                         const base::TimeDelta& delay);
  25
  26   // Destroying the notifier will ensure that no further notifications will
  27   // happen from this class.
  28   virtual ~DelayedUniqueNotifier();
  29
  30   // Schedule a notification to be run. If another notification is already
  31   // pending, then it will happen in (at least) given delay from now. That is,
  32   // if delay is 16ms and a notification has been scheduled 10ms ago (ie, it
  33   // should trigger in no less than 6ms), then calling schedule will ensure that
  34   // the only notification that arrives will happen in (at least) 16ms from now.
  35   void Schedule();
  36
  37   // Cancel any previously scheduled runs.
  38   void Cancel();
  39
  40   // Cancel previously scheduled runs and prevent any new runs from starting.
  41   // After calling this the DelayedUniqueNotifier will have no outstanding
  42   // WeakPtrs.
  43   void Shutdown();
  44
  45   // Returns true if a notification is currently scheduled to run.
  46   bool HasPendingNotification() const;
  47
  48  protected:
  49   // Virtual for testing.
  50   virtual base::TimeTicks Now() const;
  51
  52  private:
  53   void NotifyIfTime();
  54
  55   base::SequencedTaskRunner* task_runner_;
  56   base::Closure closure_;
  57   base::TimeDelta delay_;
  58   base::TimeTicks next_notification_time_;
  59   bool notification_pending_;
  60
  61   base::WeakPtrFactory<DelayedUniqueNotifier> weak_ptr_factory_;
  62
  63   DISALLOW_COPY_AND_ASSIGN(DelayedUniqueNotifier);
  64 };
  65
  66 }  // namespace cc
  67
  68 #endif  // CC_BASE_DELAYED_UNIQUE_NOTIFIER_H_