The Tor Browser: xpcom/threads/nsTimerImpl.cpp@6474c204b198 (annotated)

xpcom/threads/nsTimerImpl.cpp@6474c204b198 (annotated)

xpcom/threads/nsTimerImpl.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "nsTimerImpl.h"
 #include "TimerThread.h"
 #include "nsAutoPtr.h"
 #include "nsThreadManager.h"
 #include "nsThreadUtils.h"
 #include "plarena.h"
 #include "pratom.h"
 #include "GeckoProfiler.h"
 #include "mozilla/Atomics.h"
 using mozilla::Atomic;
 using mozilla::TimeDuration;
 using mozilla::TimeStamp;
 static Atomic<int32_t>  gGenerator;
 static TimerThread*     gThread = nullptr;
 #ifdef DEBUG_TIMERS
 PRLogModuleInfo*
 GetTimerLog()
 {
   static PRLogModuleInfo *sLog;
   if (!sLog)
     sLog = PR_NewLogModule("nsTimerImpl");
   return sLog;
 }
 #include <math.h>
 double nsTimerImpl::sDeltaSumSquared = 0;
 double nsTimerImpl::sDeltaSum = 0;
 double nsTimerImpl::sDeltaNum = 0;
 static void
 myNS_MeanAndStdDev(double n, double sumOfValues, double sumOfSquaredValues,
                    double *meanResult, double *stdDevResult)
 {
   double mean = 0.0, var = 0.0, stdDev = 0.0;
   if (n > 0.0 && sumOfValues >= 0) {
     mean = sumOfValues / n;
     double temp = (n * sumOfSquaredValues) - (sumOfValues * sumOfValues);
     if (temp < 0.0 || n <= 1)
       var = 0.0;
     else
       var = temp / (n * (n - 1));
     // for some reason, Windows says sqrt(0.0) is "-1.#J" (?!) so do this:
     stdDev = var != 0.0 ? sqrt(var) : 0.0;
   }
   *meanResult = mean;
   *stdDevResult = stdDev;
 }
 #endif
 namespace {
 // TimerEventAllocator is a thread-safe allocator used only for nsTimerEvents.
 // It's needed to avoid contention over the default allocator lock when
 // firing timer events (see bug 733277).  The thread-safety is required because
 // nsTimerEvent objects are allocated on the timer thread, and freed on another
 // thread.  Because TimerEventAllocator has its own lock, contention over that
 // lock is limited to the allocation and deallocation of nsTimerEvent objects.
 //
 // Because this allocator is layered over PLArenaPool, it never shrinks -- even
 // "freed" nsTimerEvents aren't truly freed, they're just put onto a free-list
 // for later recycling.  So the amount of memory consumed will always be equal
 // to the high-water mark consumption.  But nsTimerEvents are small and it's
 // unusual to have more than a few hundred of them, so this shouldn't be a
 // problem in practice.
 class TimerEventAllocator
 {
 private:
   struct FreeEntry {
     FreeEntry* mNext;
   };
   PLArenaPool mPool;
   FreeEntry* mFirstFree;
   mozilla::Monitor mMonitor;
 public:
   TimerEventAllocator()
     : mFirstFree(nullptr),
       mMonitor("TimerEventAllocator")
   {
     PL_InitArenaPool(&mPool, "TimerEventPool", 4096, /* align = */ 0);
   }
   ~TimerEventAllocator()
   {
     PL_FinishArenaPool(&mPool);
   }
   void* Alloc(size_t aSize);
   void Free(void* aPtr);
 };
 } // anonymous namespace
 class nsTimerEvent : public nsRunnable {
 public:
   NS_IMETHOD Run();
   nsTimerEvent()
     : mTimer()
     , mGeneration(0)
    {
     MOZ_COUNT_CTOR(nsTimerEvent);
     MOZ_ASSERT(gThread->IsOnTimerThread(),
                "nsTimer must always be allocated on the timer thread");
     sAllocatorUsers++;
   }
 #ifdef DEBUG_TIMERS
   TimeStamp mInitTime;
 #endif
   static void Init();
   static void Shutdown();
   static void DeleteAllocatorIfNeeded();
   static void* operator new(size_t size) CPP_THROW_NEW {
     return sAllocator->Alloc(size);
   }
   void operator delete(void* p) {
     sAllocator->Free(p);
     DeleteAllocatorIfNeeded();
   }
   already_AddRefed<nsTimerImpl> ForgetTimer()
   {
     return mTimer.forget();
   }
   void SetTimer(already_AddRefed<nsTimerImpl> aTimer)
   {
     mTimer = aTimer;
     mGeneration = mTimer->GetGeneration();
   }
 private:
   ~nsTimerEvent() {
     MOZ_COUNT_DTOR(nsTimerEvent);
     MOZ_ASSERT(!sCanDeleteAllocator || sAllocatorUsers > 0,
                "This will result in us attempting to deallocate the nsTimerEvent allocator twice");
     sAllocatorUsers--;
   }
   nsRefPtr<nsTimerImpl> mTimer;
   int32_t      mGeneration;
   static TimerEventAllocator* sAllocator;
   static Atomic<int32_t> sAllocatorUsers;
   static bool sCanDeleteAllocator;
 };
 TimerEventAllocator* nsTimerEvent::sAllocator = nullptr;
 Atomic<int32_t> nsTimerEvent::sAllocatorUsers;
 bool nsTimerEvent::sCanDeleteAllocator = false;
 namespace {
 void* TimerEventAllocator::Alloc(size_t aSize)
 {
   MOZ_ASSERT(aSize == sizeof(nsTimerEvent));
   mozilla::MonitorAutoLock lock(mMonitor);
   void* p;
   if (mFirstFree) {
     p = mFirstFree;
     mFirstFree = mFirstFree->mNext;
   }
   else {
     PL_ARENA_ALLOCATE(p, &mPool, aSize);
     if (!p)
       return nullptr;
   }
   return p;
 }
 void TimerEventAllocator::Free(void* aPtr)
 {
   mozilla::MonitorAutoLock lock(mMonitor);
   FreeEntry* entry = reinterpret_cast<FreeEntry*>(aPtr);
   entry->mNext = mFirstFree;
   mFirstFree = entry;
 }
 } // anonymous namespace
 NS_IMPL_QUERY_INTERFACE(nsTimerImpl, nsITimer)
 NS_IMPL_ADDREF(nsTimerImpl)
 NS_IMETHODIMP_(MozExternalRefCountType) nsTimerImpl::Release(void)
 {
   nsrefcnt count;
   MOZ_ASSERT(int32_t(mRefCnt) > 0, "dup release");
   count = --mRefCnt;
   NS_LOG_RELEASE(this, count, "nsTimerImpl");
   if (count == 0) {
     mRefCnt = 1; /* stabilize */
     /* enable this to find non-threadsafe destructors: */
     /* NS_ASSERT_OWNINGTHREAD(nsTimerImpl); */
     delete this;
     return 0;
   }
   // If only one reference remains, and mArmed is set, then the ref must be
   // from the TimerThread::mTimers array, so we Cancel this timer to remove
   // the mTimers element, and return 0 if Cancel in fact disarmed the timer.
   //
   // We use an inlined version of nsTimerImpl::Cancel here to check for the
   // NS_ERROR_NOT_AVAILABLE code returned by gThread->RemoveTimer when this
   // timer is not found in the mTimers array -- i.e., when the timer was not
   // in fact armed once we acquired TimerThread::mLock, in spite of mArmed
   // being true here.  That can happen if the armed timer is being fired by
   // TimerThread::Run as we race and test mArmed just before it is cleared by
   // the timer thread.  If the RemoveTimer call below doesn't find this timer
   // in the mTimers array, then the last ref to this timer is held manually
   // and temporarily by the TimerThread, so we should fall through to the
   // final return and return 1, not 0.
   //
   // The original version of this thread-based timer code kept weak refs from
   // TimerThread::mTimers, removing this timer's weak ref in the destructor,
   // but that leads to double-destructions in the race described above, and
   // adding mArmed doesn't help, because destructors can't be deferred, once
   // begun.  But by combining reference-counting and a specialized Release
   // method with "is this timer still in the mTimers array once we acquire
   // the TimerThread's lock" testing, we defer destruction until we're sure
   // that only one thread has its hot little hands on this timer.
   //
   // Note that both approaches preclude a timer creator, and everyone else
   // except the TimerThread who might have a strong ref, from dropping all
   // their strong refs without implicitly canceling the timer.  Timers need
   // non-mTimers-element strong refs to stay alive.
   if (count == 1 && mArmed) {
     mCanceled = true;
     MOZ_ASSERT(gThread, "Armed timer exists after the thread timer stopped.");
     if (NS_SUCCEEDED(gThread->RemoveTimer(this)))
       return 0;
   }
   return count;
 }
 nsTimerImpl::nsTimerImpl() :
   mClosure(nullptr),
   mCallbackType(CALLBACK_TYPE_UNKNOWN),
   mFiring(false),
   mArmed(false),
   mCanceled(false),
   mGeneration(0),
   mDelay(0)
 {
   // XXXbsmedberg: shouldn't this be in Init()?
   mEventTarget = static_cast<nsIEventTarget*>(NS_GetCurrentThread());
   mCallback.c = nullptr;
 }
 nsTimerImpl::~nsTimerImpl()
 {
   ReleaseCallback();
 }
 //static
 nsresult
 nsTimerImpl::Startup()
 {
   nsresult rv;
   nsTimerEvent::Init();
   gThread = new TimerThread();
   if (!gThread) return NS_ERROR_OUT_OF_MEMORY;
   NS_ADDREF(gThread);
   rv = gThread->InitLocks();
   if (NS_FAILED(rv)) {
     NS_RELEASE(gThread);
   }
   return rv;
 }
 void nsTimerImpl::Shutdown()
 {
 #ifdef DEBUG_TIMERS
   if (PR_LOG_TEST(GetTimerLog(), PR_LOG_DEBUG)) {
     double mean = 0, stddev = 0;
     myNS_MeanAndStdDev(sDeltaNum, sDeltaSum, sDeltaSumSquared, &mean, &stddev);
     PR_LOG(GetTimerLog(), PR_LOG_DEBUG, ("sDeltaNum = %f, sDeltaSum = %f, sDeltaSumSquared = %f\n", sDeltaNum, sDeltaSum, sDeltaSumSquared));
     PR_LOG(GetTimerLog(), PR_LOG_DEBUG, ("mean: %fms, stddev: %fms\n", mean, stddev));
   }
 #endif
   if (!gThread)
     return;
   gThread->Shutdown();
   NS_RELEASE(gThread);
   nsTimerEvent::Shutdown();
 }
 nsresult nsTimerImpl::InitCommon(uint32_t aType, uint32_t aDelay)
 {
   nsresult rv;
   if (NS_WARN_IF(!gThread))
     return NS_ERROR_NOT_INITIALIZED;
   if (!mEventTarget) {
     NS_ERROR("mEventTarget is NULL");
     return NS_ERROR_NOT_INITIALIZED;
   }
   rv = gThread->Init();
   if (NS_WARN_IF(NS_FAILED(rv)))
     return rv;
   /**
    * In case of re-Init, both with and without a preceding Cancel, clear the
    * mCanceled flag and assign a new mGeneration.  But first, remove any armed
    * timer from the timer thread's list.
    *
    * If we are racing with the timer thread to remove this timer and we lose,
    * the RemoveTimer call made here will fail to find this timer in the timer
    * thread's list, and will return false harmlessly.  We test mArmed here to
    * avoid the small overhead in RemoveTimer of locking the timer thread and
    * checking its list for this timer.  It's safe to test mArmed even though
    * it might be cleared on another thread in the next cycle (or even already
    * be cleared by another CPU whose store hasn't reached our CPU's cache),
    * because RemoveTimer is idempotent.
    */
   if (mArmed)
     gThread->RemoveTimer(this);
   mCanceled = false;
   mTimeout = TimeStamp();
   mGeneration = gGenerator++;
   mType = (uint8_t)aType;
   SetDelayInternal(aDelay);
   return gThread->AddTimer(this);
 }
 NS_IMETHODIMP nsTimerImpl::InitWithFuncCallback(nsTimerCallbackFunc aFunc,
                                                 void *aClosure,
                                                 uint32_t aDelay,
                                                 uint32_t aType)
 {
   if (NS_WARN_IF(!aFunc))
     return NS_ERROR_INVALID_ARG;
   ReleaseCallback();
   mCallbackType = CALLBACK_TYPE_FUNC;
   mCallback.c = aFunc;
   mClosure = aClosure;
   return InitCommon(aType, aDelay);
 }
 NS_IMETHODIMP nsTimerImpl::InitWithCallback(nsITimerCallback *aCallback,
                                             uint32_t aDelay,
                                             uint32_t aType)
 {
   if (NS_WARN_IF(!aCallback))
     return NS_ERROR_INVALID_ARG;
   ReleaseCallback();
   mCallbackType = CALLBACK_TYPE_INTERFACE;
   mCallback.i = aCallback;
   NS_ADDREF(mCallback.i);
   return InitCommon(aType, aDelay);
 }
 NS_IMETHODIMP nsTimerImpl::Init(nsIObserver *aObserver,
                                 uint32_t aDelay,
                                 uint32_t aType)
 {
   if (NS_WARN_IF(!aObserver))
     return NS_ERROR_INVALID_ARG;
   ReleaseCallback();
   mCallbackType = CALLBACK_TYPE_OBSERVER;
   mCallback.o = aObserver;
   NS_ADDREF(mCallback.o);
   return InitCommon(aType, aDelay);
 }
 NS_IMETHODIMP nsTimerImpl::Cancel()
 {
   mCanceled = true;
   if (gThread)
     gThread->RemoveTimer(this);
   ReleaseCallback();
   return NS_OK;
 }
 NS_IMETHODIMP nsTimerImpl::SetDelay(uint32_t aDelay)
 {
   if (mCallbackType == CALLBACK_TYPE_UNKNOWN && mType == TYPE_ONE_SHOT) {
     // This may happen if someone tries to re-use a one-shot timer
     // by re-setting delay instead of reinitializing the timer.
     NS_ERROR("nsITimer->SetDelay() called when the "
              "one-shot timer is not set up.");
     return NS_ERROR_NOT_INITIALIZED;
   }
   // If we're already repeating precisely, update mTimeout now so that the
   // new delay takes effect in the future.
   if (!mTimeout.IsNull() && mType == TYPE_REPEATING_PRECISE)
     mTimeout = TimeStamp::Now();
   SetDelayInternal(aDelay);
   if (!mFiring && gThread)
     gThread->TimerDelayChanged(this);
   return NS_OK;
 }
 NS_IMETHODIMP nsTimerImpl::GetDelay(uint32_t* aDelay)
 {
   *aDelay = mDelay;
   return NS_OK;
 }
 NS_IMETHODIMP nsTimerImpl::SetType(uint32_t aType)
 {
   mType = (uint8_t)aType;
   // XXX if this is called, we should change the actual type.. this could effect
   // repeating timers.  we need to ensure in Fire() that if mType has changed
   // during the callback that we don't end up with the timer in the queue twice.
   return NS_OK;
 }
 NS_IMETHODIMP nsTimerImpl::GetType(uint32_t* aType)
 {
   *aType = mType;
   return NS_OK;
 }
 NS_IMETHODIMP nsTimerImpl::GetClosure(void** aClosure)
 {
   *aClosure = mClosure;
   return NS_OK;
 }
 NS_IMETHODIMP nsTimerImpl::GetCallback(nsITimerCallback **aCallback)
 {
   if (mCallbackType == CALLBACK_TYPE_INTERFACE)
     NS_IF_ADDREF(*aCallback = mCallback.i);
   else if (mTimerCallbackWhileFiring)
     NS_ADDREF(*aCallback = mTimerCallbackWhileFiring);
   else
     *aCallback = nullptr;
   return NS_OK;
 }
 NS_IMETHODIMP nsTimerImpl::GetTarget(nsIEventTarget** aTarget)
 {
   NS_IF_ADDREF(*aTarget = mEventTarget);
   return NS_OK;
 }
 NS_IMETHODIMP nsTimerImpl::SetTarget(nsIEventTarget* aTarget)
 {
   if (NS_WARN_IF(mCallbackType != CALLBACK_TYPE_UNKNOWN))
     return NS_ERROR_ALREADY_INITIALIZED;
   if (aTarget)
     mEventTarget = aTarget;
   else
     mEventTarget = static_cast<nsIEventTarget*>(NS_GetCurrentThread());
   return NS_OK;
 }
 void nsTimerImpl::Fire()
 {
   if (mCanceled)
     return;
   PROFILER_LABEL("Timer", "Fire");
 #ifdef MOZ_TASK_TRACER
   mozilla::tasktracer::AutoRunFakeTracedTask runTracedTask(mTracedTask);
 #endif
 #ifdef DEBUG_TIMERS
   TimeStamp now = TimeStamp::Now();
   if (PR_LOG_TEST(GetTimerLog(), PR_LOG_DEBUG)) {
     TimeDuration   a = now - mStart; // actual delay in intervals
     TimeDuration   b = TimeDuration::FromMilliseconds(mDelay); // expected delay in intervals
     TimeDuration   delta = (a > b) ? a - b : b - a;
     uint32_t       d = delta.ToMilliseconds(); // delta in ms
     sDeltaSum += d;
     sDeltaSumSquared += double(d) * double(d);
     sDeltaNum++;
     PR_LOG(GetTimerLog(), PR_LOG_DEBUG, ("[this=%p] expected delay time %4ums\n", this, mDelay));
     PR_LOG(GetTimerLog(), PR_LOG_DEBUG, ("[this=%p] actual delay time   %fms\n", this, a.ToMilliseconds()));
     PR_LOG(GetTimerLog(), PR_LOG_DEBUG, ("[this=%p] (mType is %d)       -------\n", this, mType));
     PR_LOG(GetTimerLog(), PR_LOG_DEBUG, ("[this=%p]     delta           %4dms\n", this, (a > b) ? (int32_t)d : -(int32_t)d));
     mStart = mStart2;
     mStart2 = TimeStamp();
   }
 #endif
   TimeStamp timeout = mTimeout;
   if (IsRepeatingPrecisely()) {
     // Precise repeating timers advance mTimeout by mDelay without fail before
     // calling Fire().
     timeout -= TimeDuration::FromMilliseconds(mDelay);
   }
   if (mCallbackType == CALLBACK_TYPE_INTERFACE)
     mTimerCallbackWhileFiring = mCallback.i;
   mFiring = true;
   // Handle callbacks that re-init the timer, but avoid leaking.
   // See bug 330128.
   CallbackUnion callback = mCallback;
   unsigned callbackType = mCallbackType;
   if (callbackType == CALLBACK_TYPE_INTERFACE)
     NS_ADDREF(callback.i);
   else if (callbackType == CALLBACK_TYPE_OBSERVER)
     NS_ADDREF(callback.o);
   ReleaseCallback();
   switch (callbackType) {
     case CALLBACK_TYPE_FUNC:
       callback.c(this, mClosure);
       break;
     case CALLBACK_TYPE_INTERFACE:
       callback.i->Notify(this);
       break;
     case CALLBACK_TYPE_OBSERVER:
       callback.o->Observe(static_cast<nsITimer*>(this),
                           NS_TIMER_CALLBACK_TOPIC,
                           nullptr);
       break;
     default:;
   }
   // If the callback didn't re-init the timer, and it's not a one-shot timer,
   // restore the callback state.
   if (mCallbackType == CALLBACK_TYPE_UNKNOWN &&
       mType != TYPE_ONE_SHOT && !mCanceled) {
     mCallback = callback;
     mCallbackType = callbackType;
   } else {
     // The timer was a one-shot, or the callback was reinitialized.
     if (callbackType == CALLBACK_TYPE_INTERFACE)
       NS_RELEASE(callback.i);
     else if (callbackType == CALLBACK_TYPE_OBSERVER)
       NS_RELEASE(callback.o);
   }
   mFiring = false;
   mTimerCallbackWhileFiring = nullptr;
 #ifdef DEBUG_TIMERS
   if (PR_LOG_TEST(GetTimerLog(), PR_LOG_DEBUG)) {
     PR_LOG(GetTimerLog(), PR_LOG_DEBUG,
            ("[this=%p] Took %fms to fire timer callback\n",
             this, (TimeStamp::Now() - now).ToMilliseconds()));
   }
 #endif
   // Reschedule repeating timers, except REPEATING_PRECISE which already did
   // that in PostTimerEvent, but make sure that we aren't armed already (which
   // can happen if the callback reinitialized the timer).
   if (IsRepeating() && mType != TYPE_REPEATING_PRECISE && !mArmed) {
     if (mType == TYPE_REPEATING_SLACK)
       SetDelayInternal(mDelay); // force mTimeout to be recomputed.  For
                                 // REPEATING_PRECISE_CAN_SKIP timers this has
                                 // already happened.
     if (gThread)
       gThread->AddTimer(this);
   }
 }
 void nsTimerEvent::Init()
 {
   sAllocator = new TimerEventAllocator();
 }
 void nsTimerEvent::Shutdown()
 {
   sCanDeleteAllocator = true;
   DeleteAllocatorIfNeeded();
 }
 void nsTimerEvent::DeleteAllocatorIfNeeded()
 {
   if (sCanDeleteAllocator && sAllocatorUsers == 0) {
     delete sAllocator;
     sAllocator = nullptr;
   }
 }
 NS_IMETHODIMP nsTimerEvent::Run()
 {
   if (mGeneration != mTimer->GetGeneration())
     return NS_OK;
 #ifdef DEBUG_TIMERS
   if (PR_LOG_TEST(GetTimerLog(), PR_LOG_DEBUG)) {
     TimeStamp now = TimeStamp::Now();
     PR_LOG(GetTimerLog(), PR_LOG_DEBUG,
            ("[this=%p] time between PostTimerEvent() and Fire(): %fms\n",
             this, (now - mInitTime).ToMilliseconds()));
   }
 #endif
   mTimer->Fire();
   // Since nsTimerImpl is not thread-safe, we should release |mTimer|
   // here in the target thread to avoid race condition. Otherwise,
   // ~nsTimerEvent() which calls nsTimerImpl::Release() could run in the
   // timer thread and result in race condition.
   mTimer = nullptr;
   return NS_OK;
 }
 already_AddRefed<nsTimerImpl>
 nsTimerImpl::PostTimerEvent(already_AddRefed<nsTimerImpl> aTimerRef)
 {
   nsRefPtr<nsTimerImpl> timer(aTimerRef);
   if (!timer->mEventTarget) {
     NS_ERROR("Attempt to post timer event to NULL event target");
     return timer.forget();
   }
   // XXX we may want to reuse this nsTimerEvent in the case of repeating timers.
   // Since TimerThread addref'd 'timer' for us, we don't need to addref here.
   // We will release either in ~nsTimerEvent(), or pass the reference back to
   // the caller. We need to copy the generation number from this timer into the
   // event, so we can avoid firing a timer that was re-initialized after being
   // canceled.
   // Note: We override operator new for this class, and the override is
   // fallible!
   nsRefPtr<nsTimerEvent> event = new nsTimerEvent;
   if (!event)
     return timer.forget();
 #ifdef DEBUG_TIMERS
   if (PR_LOG_TEST(GetTimerLog(), PR_LOG_DEBUG)) {
     event->mInitTime = TimeStamp::Now();
   }
 #endif
   // If this is a repeating precise timer, we need to calculate the time for
   // the next timer to fire before we make the callback.
   if (timer->IsRepeatingPrecisely()) {
     timer->SetDelayInternal(timer->mDelay);
     // But only re-arm REPEATING_PRECISE timers.
     if (gThread && timer->mType == TYPE_REPEATING_PRECISE) {
       nsresult rv = gThread->AddTimer(timer);
       if (NS_FAILED(rv)) {
         return timer.forget();
       }
     }
   }
   nsIEventTarget* target = timer->mEventTarget;
   event->SetTimer(timer.forget());
   nsresult rv = target->Dispatch(event, NS_DISPATCH_NORMAL);
   if (NS_FAILED(rv)) {
     timer = event->ForgetTimer();
     if (gThread) {
       gThread->RemoveTimer(timer);
     }
     return timer.forget();
   }
   return nullptr;
 }
 void nsTimerImpl::SetDelayInternal(uint32_t aDelay)
 {
   TimeDuration delayInterval = TimeDuration::FromMilliseconds(aDelay);
   mDelay = aDelay;
   TimeStamp now = TimeStamp::Now();
   if (mTimeout.IsNull() || mType != TYPE_REPEATING_PRECISE)
     mTimeout = now;
   mTimeout += delayInterval;
 #ifdef DEBUG_TIMERS
   if (PR_LOG_TEST(GetTimerLog(), PR_LOG_DEBUG)) {
     if (mStart.IsNull())
       mStart = now;
     else
       mStart2 = now;
   }
 #endif
 }
 // NOT FOR PUBLIC CONSUMPTION!
 nsresult
 NS_NewTimer(nsITimer* *aResult, nsTimerCallbackFunc aCallback, void *aClosure,
             uint32_t aDelay, uint32_t aType)
 {
     nsTimerImpl* timer = new nsTimerImpl();
     if (timer == nullptr)
         return NS_ERROR_OUT_OF_MEMORY;
     NS_ADDREF(timer);
     nsresult rv = timer->InitWithFuncCallback(aCallback, aClosure,
                                               aDelay, aType);
     if (NS_FAILED(rv)) {
         NS_RELEASE(timer);
         return rv;
     }
     *aResult = timer;
     return NS_OK;
 }

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xpcom/threads/nsTimerImpl.cpp@6474c204b198 (annotated)

xpcom/threads/nsTimerImpl.cpp