xpcom/threads/DelayedRunnable.cpp

   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 #include "DelayedRunnable.h"
   8
   9 #include "mozilla/ProfilerRunnable.h"
  10
  11 namespace mozilla {
  12
  13 DelayedRunnable::DelayedRunnable(already_AddRefed<nsISerialEventTarget> aTarget,
  14                                  already_AddRefed<nsIRunnable> aRunnable,
  15                                  uint32_t aDelay)
  16     : mozilla::Runnable("DelayedRunnable"),
  17       mTarget(aTarget),
  18       mDelayedFrom(TimeStamp::NowLoRes()),
  19       mDelay(aDelay),
  20       mWrappedRunnable(aRunnable) {}
  21
  22 nsresult DelayedRunnable::Init() {
  23   MutexAutoLock lock(mMutex);
  24   if (!mWrappedRunnable) {
  25     MOZ_ASSERT_UNREACHABLE();
  26     return NS_ERROR_INVALID_ARG;
  27   }
  28
  29   nsresult rv = mTarget->RegisterShutdownTask(this);
  30   if (NS_FAILED(rv)) {
  31     MOZ_DIAGNOSTIC_ASSERT(
  32         rv == NS_ERROR_UNEXPECTED,
  33         "DelayedRunnable target must support RegisterShutdownTask");
  34     NS_WARNING("DelayedRunnable init after target is shutdown");
  35     return rv;
  36   }
  37
  38   rv = NS_NewTimerWithCallback(getter_AddRefs(mTimer), this, mDelay,
  39                                nsITimer::TYPE_ONE_SHOT, mTarget);
  40   if (NS_WARN_IF(NS_FAILED(rv))) {
  41     mTarget->UnregisterShutdownTask(this);
  42   }
  43   return rv;
  44 }
  45
  46 NS_IMETHODIMP DelayedRunnable::Run() {
  47   MOZ_ASSERT(mTarget->IsOnCurrentThread());
  48
  49   nsCOMPtr<nsIRunnable> runnable;
  50   {
  51     MutexAutoLock lock(mMutex);
  52     MOZ_ASSERT(mTimer, "Init() must have been called");
  53
  54     // Already ran?
  55     if (!mWrappedRunnable) {
  56       return NS_OK;
  57     }
  58
  59     // Are we too early?
  60     if ((mozilla::TimeStamp::NowLoRes() - mDelayedFrom).ToMilliseconds() <
  61         mDelay) {
  62       return NS_OK;  // Let the nsITimer run us.
  63     }
  64
  65     mTimer->Cancel();
  66     mTarget->UnregisterShutdownTask(this);
  67     runnable = mWrappedRunnable.forget();
  68   }
  69
  70   AUTO_PROFILE_FOLLOWING_RUNNABLE(runnable);
  71   return runnable->Run();
  72 }
  73
  74 NS_IMETHODIMP DelayedRunnable::Notify(nsITimer* aTimer) {
  75   MOZ_ASSERT(mTarget->IsOnCurrentThread());
  76
  77   nsCOMPtr<nsIRunnable> runnable;
  78   {
  79     MutexAutoLock lock(mMutex);
  80     MOZ_ASSERT(mTimer, "Init() must have been called");
  81
  82     // We may have already run due to races
  83     if (!mWrappedRunnable) {
  84       return NS_OK;
  85     }
  86
  87     mTarget->UnregisterShutdownTask(this);
  88     runnable = mWrappedRunnable.forget();
  89   }
  90
  91   AUTO_PROFILE_FOLLOWING_RUNNABLE(runnable);
  92   return runnable->Run();
  93 }
  94
  95 void DelayedRunnable::TargetShutdown() {
  96   MOZ_ASSERT(mTarget->IsOnCurrentThread());
  97
  98   // Called at shutdown
  99   MutexAutoLock lock(mMutex);
 100   if (!mWrappedRunnable) {
 101     return;
 102   }
 103   mWrappedRunnable = nullptr;
 104
 105   if (mTimer) {
 106     mTimer->Cancel();
 107   }
 108 }
 109
 110 NS_IMPL_ISUPPORTS_INHERITED(DelayedRunnable, Runnable, nsITimerCallback,
 111                             nsITargetShutdownTask)
 112
 113 }  // namespace mozilla