xpcom/threads/TimerThread.h

   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 TimerThread_h___
   8 #define TimerThread_h___
   9
  10 #include "nsIObserver.h"
  11 #include "nsIRunnable.h"
  12 #include "nsIThread.h"
  13
  14 #include "nsTimerImpl.h"
  15 #include "nsThreadUtils.h"
  16
  17 #include "nsTArray.h"
  18
  19 #include "mozilla/Atomics.h"
  20 #include "mozilla/Attributes.h"
  21 #include "mozilla/Monitor.h"
  22 #include "mozilla/ProfilerUtils.h"
  23 #include "mozilla/UniquePtr.h"
  24
  25 #include <algorithm>
  26
  27 namespace mozilla {
  28 class TimeStamp;
  29 }  // namespace mozilla
  30
  31 class TimerThread final : public mozilla::Runnable, public nsIObserver {
  32  public:
  33   typedef mozilla::Monitor Monitor;
  34   typedef mozilla::MutexAutoLock MutexAutoLock;
  35   typedef mozilla::TimeStamp TimeStamp;
  36   typedef mozilla::TimeDuration TimeDuration;
  37
  38   TimerThread();
  39   nsresult InitLocks();
  40
  41   NS_DECL_ISUPPORTS_INHERITED
  42   NS_DECL_NSIRUNNABLE
  43   NS_DECL_NSIOBSERVER
  44
  45   nsresult Shutdown();
  46
  47   nsresult AddTimer(nsTimerImpl* aTimer, const MutexAutoLock& aProofOfLock);
  48   nsresult RemoveTimer(nsTimerImpl* aTimer, const MutexAutoLock& aProofOfLock);
  49   TimeStamp FindNextFireTimeForCurrentThread(TimeStamp aDefault,
  50                                              uint32_t aSearchBound);
  51
  52   void DoBeforeSleep();
  53   void DoAfterSleep();
  54
  55   bool IsOnTimerThread() const {
  56     return mThread->SerialEventTarget()->IsOnCurrentThread();
  57   }
  58
  59   uint32_t AllowedEarlyFiringMicroseconds();
  60
  61  private:
  62   ~TimerThread();
  63
  64   bool mInitialized;
  65
  66   // These internal helper methods must be called while mMonitor is held.
  67   // AddTimerInternal returns false if the insertion failed.
  68   bool AddTimerInternal(nsTimerImpl* aTimer);
  69   bool RemoveTimerInternal(nsTimerImpl* aTimer);
  70   void RemoveLeadingCanceledTimersInternal();
  71   void RemoveFirstTimerInternal();
  72   nsresult Init();
  73
  74   void PostTimerEvent(already_AddRefed<nsTimerImpl> aTimerRef);
  75
  76   nsCOMPtr<nsIThread> mThread;
  77   // Lock ordering requirements:
  78   // (optional) ThreadWrapper::sMutex ->
  79   // (optional) nsTimerImpl::mMutex   ->
  80   // TimerThread::mMonitor
  81   Monitor mMonitor;
  82
  83   bool mShutdown;
  84   bool mWaiting;
  85   bool mNotified;
  86   bool mSleeping;
  87
  88   class Entry final : public nsTimerImplHolder {
  89     const TimeStamp mTimeout;
  90
  91    public:
  92     // Entries are created with the TimerImpl's mutex held.
  93     // nsTimerImplHolder() will call SetHolder()
  94     Entry(const TimeStamp& aMinTimeout, const TimeStamp& aTimeout,
  95           nsTimerImpl* aTimerImpl)
  96         : nsTimerImplHolder(aTimerImpl),
  97           mTimeout(std::max(aMinTimeout, aTimeout)) {}
  98
  99     nsTimerImpl* Value() const { return mTimerImpl; }
 100
 101     // Called with the Monitor held, but not the TimerImpl's mutex
 102     already_AddRefed<nsTimerImpl> Take() {
 103       if (mTimerImpl) {
 104         MOZ_ASSERT(mTimerImpl->mHolder == this);
 105         mTimerImpl->SetHolder(nullptr);
 106       }
 107       return mTimerImpl.forget();
 108     }
 109
 110     static bool UniquePtrLessThan(mozilla::UniquePtr<Entry>& aLeft,
 111                                   mozilla::UniquePtr<Entry>& aRight) {
 112       // This is reversed because std::push_heap() sorts the "largest" to
 113       // the front of the heap.  We want that to be the earliest timer.
 114       return aRight->mTimeout < aLeft->mTimeout;
 115     }
 116
 117     TimeStamp Timeout() const { return mTimeout; }
 118   };
 119
 120   nsTArray<mozilla::UniquePtr<Entry>> mTimers;
 121   // Set only at the start of the thread's Run():
 122   uint32_t mAllowedEarlyFiringMicroseconds;
 123   ProfilerThreadId mProfilerThreadId;
 124 };
 125
 126 #endif /* TimerThread_h___ */