1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
3 /* This Source Code Form is subject to the terms of the Mozilla Public
4  * License, v. 2.0. If a copy of the MPL was not distributed with this
5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 
7 #ifndef mozilla_dom_timeoutexecutor_h
8 #define mozilla_dom_timeoutexecutor_h
9 
10 #include "mozilla/TimeStamp.h"
11 #include "nsCOMPtr.h"
12 #include "nsIRunnable.h"
13 #include "nsITimer.h"
14 #include "nsINamed.h"
15 
16 namespace mozilla {
17 namespace dom {
18 
19 class TimeoutManager;
20 
21 class TimeoutExecutor final : public nsIRunnable,
22                               public nsITimerCallback,
23                               public nsINamed {
24   TimeoutManager* mOwner;
25   bool mIsIdleQueue;
26   nsCOMPtr<nsITimer> mTimer;
27   TimeStamp mDeadline;
28   uint32_t mMaxIdleDeferMS;
29 
30   // Limits how far we allow timers to fire into the future from their
31   // deadline.  Starts off at zero, but is then adjusted when we start
32   // using nsITimer.  The nsITimer implementation may sometimes fire
33   // early and we should allow that to minimize additional wakeups.
34   TimeDuration mAllowedEarlyFiringTime;
35 
36   // The TimeoutExecutor is repeatedly scheduled by the TimeoutManager
37   // to fire for the next soonest Timeout.  Since the executor is re-used
38   // it needs to handle switching between a few states.
39   enum class Mode {
40     // None indicates the executor is idle.  It may be scheduled or shutdown.
41     None,
42     // Immediate means the executor is scheduled to run a Timeout with a
43     // deadline that has already expired.
44     Immediate,
45     // Delayed means the executor is scheduled to run a Timeout with a
46     // deadline in the future.
47     Delayed,
48     // Shutdown means the TimeoutManager has been destroyed.  Once this
49     // state is reached the executor cannot be scheduled again.  If the
50     // executor is already dispatched as a runnable or held by a timer then
51     // we may still get a Run()/Notify() call which will be ignored.
52     Shutdown
53   };
54 
55   Mode mMode;
56 
57   ~TimeoutExecutor();
58 
59   nsresult ScheduleImmediate(const TimeStamp& aDeadline, const TimeStamp& aNow);
60 
61   nsresult ScheduleDelayed(const TimeStamp& aDeadline, const TimeStamp& aNow,
62                            const TimeDuration& aMinDelay);
63 
64   nsresult Schedule(const TimeStamp& aDeadline, const TimeDuration& aMinDelay);
65 
66   nsresult MaybeReschedule(const TimeStamp& aDeadline,
67                            const TimeDuration& aMinDelay);
68 
69   MOZ_CAN_RUN_SCRIPT void MaybeExecute();
70 
71  public:
72   TimeoutExecutor(TimeoutManager* aOwner, bool aIsIdleQueue,
73                   uint32_t aMaxIdleDeferMS);
74 
75   void Shutdown();
76 
77   nsresult MaybeSchedule(const TimeStamp& aDeadline,
78                          const TimeDuration& aMinDelay);
79 
80   void Cancel();
81 
82   NS_DECL_ISUPPORTS
83   NS_DECL_NSIRUNNABLE
84   NS_DECL_NSITIMERCALLBACK
85   NS_DECL_NSINAMED
86 };
87 
88 }  // namespace dom
89 }  // namespace mozilla
90 
91 #endif  // mozilla_dom_timeoutexecutor_h
92