xpcom/threads/nsTimerImpl.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 "nsTimerImpl.h"
   8
   9 #include <utility>
  10
  11 #include "TimerThread.h"
  12 #include "mozilla/Atomics.h"
  13 #include "mozilla/IntegerPrintfMacros.h"
  14 #include "mozilla/Logging.h"
  15 #include "mozilla/Mutex.h"
  16 #include "mozilla/ProfilerLabels.h"
  17 #include "mozilla/ResultExtensions.h"
  18 #include "mozilla/Sprintf.h"
  19 #include "mozilla/StaticMutex.h"
  20 #include "mozilla/Try.h"
  21 #include "nsThreadManager.h"
  22 #include "nsThreadUtils.h"
  23 #include "pratom.h"
  24
  25 #ifdef XP_WIN
  26 #  include <process.h>
  27 #  ifndef getpid
  28 #    define getpid _getpid
  29 #  endif
  30 #else
  31 #  include <unistd.h>
  32 #endif
  33
  34 using mozilla::Atomic;
  35 using mozilla::LogLevel;
  36 using mozilla::MakeRefPtr;
  37 using mozilla::MutexAutoLock;
  38 using mozilla::TimeDuration;
  39 using mozilla::TimeStamp;
  40
  41 // Holds the timer thread and manages all interactions with it
  42 // under a locked mutex. This wrapper is not destroyed until after
  43 // nsThreadManager shutdown to ensure we don't UAF during an offthread access to
  44 // the timer thread.
  45 class TimerThreadWrapper {
  46  public:
  47   constexpr TimerThreadWrapper() : mThread(nullptr) {};
  48   ~TimerThreadWrapper() = default;
  49
  50   nsresult Init();
  51   void Shutdown();
  52
  53   nsresult AddTimer(nsTimerImpl* aTimer, const MutexAutoLock& aProofOfLock)
  54       MOZ_REQUIRES(aTimer->mMutex);
  55   nsresult RemoveTimer(nsTimerImpl* aTimer, const MutexAutoLock& aProofOfLock)
  56       MOZ_REQUIRES(aTimer->mMutex);
  57   TimeStamp FindNextFireTimeForCurrentThread(TimeStamp aDefault,
  58                                              uint32_t aSearchBound);
  59   uint32_t AllowedEarlyFiringMicroseconds();
  60   nsresult GetTimers(nsTArray<RefPtr<nsITimer>>& aRetVal);
  61
  62  private:
  63   static mozilla::StaticMutex sMutex;
  64   TimerThread* mThread MOZ_GUARDED_BY(sMutex);
  65 };
  66
  67 mozilla::StaticMutex TimerThreadWrapper::sMutex;
  68
  69 nsresult TimerThreadWrapper::Init() {
  70   mozilla::StaticMutexAutoLock lock(sMutex);
  71   mThread = new TimerThread();
  72
  73   NS_ADDREF(mThread);
  74
  75   return NS_OK;
  76 }
  77
  78 void TimerThreadWrapper::Shutdown() {
  79   RefPtr<TimerThread> thread;
  80
  81   {
  82     mozilla::StaticMutexAutoLock lock(sMutex);
  83     if (!mThread) {
  84       return;
  85     }
  86     thread = mThread;
  87   }
  88   // Shutdown calls |nsTimerImpl::Cancel| which needs to make a call into
  89   // |RemoveTimer|. This can't be done under the lock.
  90   thread->Shutdown();
  91
  92   {
  93     mozilla::StaticMutexAutoLock lock(sMutex);
  94     NS_RELEASE(mThread);
  95   }
  96 }
  97
  98 nsresult TimerThreadWrapper::AddTimer(nsTimerImpl* aTimer,
  99                                       const MutexAutoLock& aProofOfLock) {
 100   mozilla::StaticMutexAutoLock lock(sMutex);
 101   if (mThread) {
 102     return mThread->AddTimer(aTimer, aProofOfLock);
 103   }
 104   return NS_ERROR_NOT_AVAILABLE;
 105 }
 106
 107 nsresult TimerThreadWrapper::RemoveTimer(nsTimerImpl* aTimer,
 108                                          const MutexAutoLock& aProofOfLock) {
 109   mozilla::StaticMutexAutoLock lock(sMutex);
 110   if (mThread) {
 111     return mThread->RemoveTimer(aTimer, aProofOfLock);
 112   }
 113   return NS_ERROR_NOT_AVAILABLE;
 114 }
 115
 116 TimeStamp TimerThreadWrapper::FindNextFireTimeForCurrentThread(
 117     TimeStamp aDefault, uint32_t aSearchBound) {
 118   mozilla::StaticMutexAutoLock lock(sMutex);
 119   return mThread
 120              ? mThread->FindNextFireTimeForCurrentThread(aDefault, aSearchBound)
 121              : TimeStamp();
 122 }
 123
 124 uint32_t TimerThreadWrapper::AllowedEarlyFiringMicroseconds() {
 125   mozilla::StaticMutexAutoLock lock(sMutex);
 126   return mThread ? mThread->AllowedEarlyFiringMicroseconds() : 0;
 127 }
 128
 129 nsresult TimerThreadWrapper::GetTimers(nsTArray<RefPtr<nsITimer>>& aRetVal) {
 130   RefPtr<TimerThread> thread;
 131   {
 132     mozilla::StaticMutexAutoLock lock(sMutex);
 133     if (!mThread) {
 134       return NS_ERROR_NOT_AVAILABLE;
 135     }
 136     thread = mThread;
 137   }
 138   return thread->GetTimers(aRetVal);
 139 }
 140
 141 static TimerThreadWrapper gThreadWrapper;
 142
 143 // This module prints info about the precision of timers.
 144 static mozilla::LazyLogModule sTimerLog("nsTimerImpl");
 145
 146 mozilla::LogModule* GetTimerLog() { return sTimerLog; }
 147
 148 TimeStamp NS_GetTimerDeadlineHintOnCurrentThread(TimeStamp aDefault,
 149                                                  uint32_t aSearchBound) {
 150   return gThreadWrapper.FindNextFireTimeForCurrentThread(aDefault,
 151                                                          aSearchBound);
 152 }
 153
 154 already_AddRefed<nsITimer> NS_NewTimer() { return NS_NewTimer(nullptr); }
 155
 156 already_AddRefed<nsITimer> NS_NewTimer(nsIEventTarget* aTarget) {
 157   return nsTimer::WithEventTarget(aTarget).forget();
 158 }
 159
 160 mozilla::Result<nsCOMPtr<nsITimer>, nsresult> NS_NewTimerWithObserver(
 161     nsIObserver* aObserver, uint32_t aDelay, uint32_t aType,
 162     nsIEventTarget* aTarget) {
 163   nsCOMPtr<nsITimer> timer;
 164   MOZ_TRY(NS_NewTimerWithObserver(getter_AddRefs(timer), aObserver, aDelay,
 165                                   aType, aTarget));
 166   return std::move(timer);
 167 }
 168 nsresult NS_NewTimerWithObserver(nsITimer** aTimer, nsIObserver* aObserver,
 169                                  uint32_t aDelay, uint32_t aType,
 170                                  nsIEventTarget* aTarget) {
 171   auto timer = nsTimer::WithEventTarget(aTarget);
 172
 173   MOZ_TRY(timer->Init(aObserver, aDelay, aType));
 174   timer.forget(aTimer);
 175   return NS_OK;
 176 }
 177
 178 mozilla::Result<nsCOMPtr<nsITimer>, nsresult> NS_NewTimerWithCallback(
 179     nsITimerCallback* aCallback, uint32_t aDelay, uint32_t aType,
 180     nsIEventTarget* aTarget) {
 181   nsCOMPtr<nsITimer> timer;
 182   MOZ_TRY(NS_NewTimerWithCallback(getter_AddRefs(timer), aCallback, aDelay,
 183                                   aType, aTarget));
 184   return std::move(timer);
 185 }
 186 nsresult NS_NewTimerWithCallback(nsITimer** aTimer, nsITimerCallback* aCallback,
 187                                  uint32_t aDelay, uint32_t aType,
 188                                  nsIEventTarget* aTarget) {
 189   auto timer = nsTimer::WithEventTarget(aTarget);
 190
 191   MOZ_TRY(timer->InitWithCallback(aCallback, aDelay, aType));
 192   timer.forget(aTimer);
 193   return NS_OK;
 194 }
 195
 196 mozilla::Result<nsCOMPtr<nsITimer>, nsresult> NS_NewTimerWithCallback(
 197     nsITimerCallback* aCallback, const TimeDuration& aDelay, uint32_t aType,
 198     nsIEventTarget* aTarget) {
 199   nsCOMPtr<nsITimer> timer;
 200   MOZ_TRY(NS_NewTimerWithCallback(getter_AddRefs(timer), aCallback, aDelay,
 201                                   aType, aTarget));
 202   return std::move(timer);
 203 }
 204 nsresult NS_NewTimerWithCallback(nsITimer** aTimer, nsITimerCallback* aCallback,
 205                                  const TimeDuration& aDelay, uint32_t aType,
 206                                  nsIEventTarget* aTarget) {
 207   auto timer = nsTimer::WithEventTarget(aTarget);
 208
 209   MOZ_TRY(timer->InitHighResolutionWithCallback(aCallback, aDelay, aType));
 210   timer.forget(aTimer);
 211   return NS_OK;
 212 }
 213
 214 mozilla::Result<nsCOMPtr<nsITimer>, nsresult> NS_NewTimerWithCallback(
 215     std::function<void(nsITimer*)>&& aCallback, uint32_t aDelay, uint32_t aType,
 216     const char* aNameString, nsIEventTarget* aTarget) {
 217   nsCOMPtr<nsITimer> timer;
 218   MOZ_TRY(NS_NewTimerWithCallback(getter_AddRefs(timer), std::move(aCallback),
 219                                   aDelay, aType, aNameString, aTarget));
 220   return timer;
 221 }
 222 nsresult NS_NewTimerWithCallback(nsITimer** aTimer,
 223                                  std::function<void(nsITimer*)>&& aCallback,
 224                                  uint32_t aDelay, uint32_t aType,
 225                                  const char* aNameString,
 226                                  nsIEventTarget* aTarget) {
 227   return NS_NewTimerWithCallback(aTimer, std::move(aCallback),
 228                                  TimeDuration::FromMilliseconds(aDelay), aType,
 229                                  aNameString, aTarget);
 230 }
 231
 232 mozilla::Result<nsCOMPtr<nsITimer>, nsresult> NS_NewTimerWithCallback(
 233     std::function<void(nsITimer*)>&& aCallback, const TimeDuration& aDelay,
 234     uint32_t aType, const char* aNameString, nsIEventTarget* aTarget) {
 235   nsCOMPtr<nsITimer> timer;
 236   MOZ_TRY(NS_NewTimerWithCallback(getter_AddRefs(timer), std::move(aCallback),
 237                                   aDelay, aType, aNameString, aTarget));
 238   return timer;
 239 }
 240 nsresult NS_NewTimerWithCallback(nsITimer** aTimer,
 241                                  std::function<void(nsITimer*)>&& aCallback,
 242                                  const TimeDuration& aDelay, uint32_t aType,
 243                                  const char* aNameString,
 244                                  nsIEventTarget* aTarget) {
 245   RefPtr<nsTimer> timer = nsTimer::WithEventTarget(aTarget);
 246
 247   MOZ_TRY(timer->InitWithClosureCallback(std::move(aCallback), aDelay, aType,
 248                                          aNameString));
 249   timer.forget(aTimer);
 250   return NS_OK;
 251 }
 252
 253 mozilla::Result<nsCOMPtr<nsITimer>, nsresult> NS_NewTimerWithFuncCallback(
 254     nsTimerCallbackFunc aCallback, void* aClosure, uint32_t aDelay,
 255     uint32_t aType, const char* aNameString, nsIEventTarget* aTarget) {
 256   nsCOMPtr<nsITimer> timer;
 257   MOZ_TRY(NS_NewTimerWithFuncCallback(getter_AddRefs(timer), aCallback,
 258                                       aClosure, aDelay, aType, aNameString,
 259                                       aTarget));
 260   return std::move(timer);
 261 }
 262 nsresult NS_NewTimerWithFuncCallback(nsITimer** aTimer,
 263                                      nsTimerCallbackFunc aCallback,
 264                                      void* aClosure, uint32_t aDelay,
 265                                      uint32_t aType, const char* aNameString,
 266                                      nsIEventTarget* aTarget) {
 267   auto timer = nsTimer::WithEventTarget(aTarget);
 268
 269   MOZ_TRY(timer->InitWithNamedFuncCallback(aCallback, aClosure, aDelay, aType,
 270                                            aNameString));
 271   timer.forget(aTimer);
 272   return NS_OK;
 273 }
 274
 275 mozilla::Result<nsCOMPtr<nsITimer>, nsresult> NS_NewTimerWithFuncCallback(
 276     nsTimerCallbackFunc aCallback, void* aClosure, const TimeDuration& aDelay,
 277     uint32_t aType, const char* aNameString, nsIEventTarget* aTarget) {
 278   nsCOMPtr<nsITimer> timer;
 279   MOZ_TRY(NS_NewTimerWithFuncCallback(getter_AddRefs(timer), aCallback,
 280                                       aClosure, aDelay, aType, aNameString,
 281                                       aTarget));
 282   return std::move(timer);
 283 }
 284 nsresult NS_NewTimerWithFuncCallback(nsITimer** aTimer,
 285                                      nsTimerCallbackFunc aCallback,
 286                                      void* aClosure, const TimeDuration& aDelay,
 287                                      uint32_t aType, const char* aNameString,
 288                                      nsIEventTarget* aTarget) {
 289   auto timer = nsTimer::WithEventTarget(aTarget);
 290
 291   MOZ_TRY(timer->InitHighResolutionWithNamedFuncCallback(
 292       aCallback, aClosure, aDelay, aType, aNameString));
 293   timer.forget(aTimer);
 294   return NS_OK;
 295 }
 296
 297 // This module prints info about which timers are firing, which is useful for
 298 // wakeups for the purposes of power profiling. Set the following environment
 299 // variable before starting the browser.
 300 //
 301 //   MOZ_LOG=TimerFirings:4
 302 //
 303 // Then a line will be printed for every timer that fires.
 304 //
 305 // If you redirect this output to a file called "out", you can then
 306 // post-process it with a command something like the following.
 307 //
 308 //   cat out | grep timer | sort | uniq -c | sort -r -n
 309 //
 310 // This will show how often each unique line appears, with the most common ones
 311 // first.
 312 //
 313 // More detailed docs are here:
 314 // https://developer.mozilla.org/en-US/docs/Mozilla/Performance/TimerFirings_logging
 315 //
 316 static mozilla::LazyLogModule sTimerFiringsLog("TimerFirings");
 317
 318 static mozilla::LogModule* GetTimerFiringsLog() { return sTimerFiringsLog; }
 319
 320 #include <math.h>
 321
 322 /* static */
 323 mozilla::StaticMutex nsTimerImpl::sDeltaMutex;
 324 /* static */
 325 double nsTimerImpl::sDeltaSumSquared MOZ_GUARDED_BY(nsTimerImpl::sDeltaMutex) =
 326     0;
 327 /* static */
 328 double nsTimerImpl::sDeltaSum MOZ_GUARDED_BY(nsTimerImpl::sDeltaMutex) = 0;
 329 /* static */
 330 double nsTimerImpl::sDeltaNum MOZ_GUARDED_BY(nsTimerImpl::sDeltaMutex) = 0;
 331
 332 static void myNS_MeanAndStdDev(double n, double sumOfValues,
 333                                double sumOfSquaredValues, double* meanResult,
 334                                double* stdDevResult) {
 335   double mean = 0.0, var = 0.0, stdDev = 0.0;
 336   if (n > 0.0 && sumOfValues >= 0) {
 337     mean = sumOfValues / n;
 338     double temp = (n * sumOfSquaredValues) - (sumOfValues * sumOfValues);
 339     if (temp < 0.0 || n <= 1) {
 340       var = 0.0;
 341     } else {
 342       var = temp / (n * (n - 1));
 343     }
 344     // for some reason, Windows says sqrt(0.0) is "-1.#J" (?!) so do this:
 345     stdDev = var != 0.0 ? sqrt(var) : 0.0;
 346   }
 347   *meanResult = mean;
 348   *stdDevResult = stdDev;
 349 }
 350
 351 NS_IMPL_QUERY_INTERFACE(nsTimer, nsITimer)
 352 NS_IMPL_ADDREF(nsTimer)
 353
 354 NS_IMPL_ISUPPORTS(nsTimerManager, nsITimerManager)
 355
 356 NS_IMETHODIMP nsTimerManager::GetTimers(nsTArray<RefPtr<nsITimer>>& aRetVal) {
 357   return gThreadWrapper.GetTimers(aRetVal);
 358 }
 359
 360 NS_IMETHODIMP_(MozExternalRefCountType)
 361 nsTimer::Release(void) {
 362   nsrefcnt count = --mRefCnt;
 363   NS_LOG_RELEASE(this, count, "nsTimer");
 364
 365   if (count == 1) {
 366     // Last ref, in nsTimerImpl::mITimer. Make sure the cycle is broken.
 367     mImpl->CancelImpl(true);
 368   } else if (count == 0) {
 369     delete this;
 370   }
 371
 372   return count;
 373 }
 374
 375 nsTimerImpl::nsTimerImpl(nsITimer* aTimer, nsIEventTarget* aTarget)
 376     : mEventTarget(aTarget),
 377       mIsInTimerThread(false),
 378       mType(0),
 379       mGeneration(0),
 380       mITimer(aTimer),
 381       mMutex("nsTimerImpl::mMutex"),
 382       mCallback(UnknownCallback{}),
 383       mFiring(0) {
 384   // XXX some code creates timers during xpcom shutdown, when threads are no
 385   // longer available, so we cannot turn this on yet.
 386   // MOZ_ASSERT(mEventTarget);
 387 }
 388
 389 // static
 390 nsresult nsTimerImpl::Startup() { return gThreadWrapper.Init(); }
 391
 392 void nsTimerImpl::Shutdown() {
 393   if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
 394     mozilla::StaticMutexAutoLock lock(sDeltaMutex);
 395     double mean = 0, stddev = 0;
 396     myNS_MeanAndStdDev(sDeltaNum, sDeltaSum, sDeltaSumSquared, &mean, &stddev);
 397
 398     MOZ_LOG(GetTimerLog(), LogLevel::Debug,
 399             ("sDeltaNum = %f, sDeltaSum = %f, sDeltaSumSquared = %f\n",
 400              sDeltaNum, sDeltaSum, sDeltaSumSquared));
 401     MOZ_LOG(GetTimerLog(), LogLevel::Debug,
 402             ("mean: %fms, stddev: %fms\n", mean, stddev));
 403   }
 404
 405   gThreadWrapper.Shutdown();
 406 }
 407
 408 nsresult nsTimerImpl::InitCommon(const TimeDuration& aDelay, uint32_t aType,
 409                                  Callback&& newCallback,
 410                                  const MutexAutoLock& aProofOfLock) {
 411   if (!mEventTarget) {
 412     return NS_ERROR_NOT_INITIALIZED;
 413   }
 414
 415   gThreadWrapper.RemoveTimer(this, aProofOfLock);
 416
 417   // If we have an existing callback, using `swap` ensures it's destroyed after
 418   // the mutex is unlocked in our caller.
 419   std::swap(mCallback, newCallback);
 420   ++mGeneration;
 421
 422   mType = (uint8_t)aType;
 423   mDelay = aDelay;
 424   mTimeout = TimeStamp::Now() + mDelay;
 425
 426   return gThreadWrapper.AddTimer(this, aProofOfLock);
 427 }
 428
 429 nsresult nsTimerImpl::InitWithNamedFuncCallback(nsTimerCallbackFunc aFunc,
 430                                                 void* aClosure, uint32_t aDelay,
 431                                                 uint32_t aType,
 432                                                 const char* aName) {
 433   return InitHighResolutionWithNamedFuncCallback(
 434       aFunc, aClosure, TimeDuration::FromMilliseconds(aDelay), aType, aName);
 435 }
 436
 437 nsresult nsTimerImpl::InitHighResolutionWithNamedFuncCallback(
 438     nsTimerCallbackFunc aFunc, void* aClosure, const TimeDuration& aDelay,
 439     uint32_t aType, const char* aName) {
 440   if (NS_WARN_IF(!aFunc)) {
 441     return NS_ERROR_INVALID_ARG;
 442   }
 443
 444   Callback cb{FuncCallback{aFunc, aClosure, aName}};
 445
 446   MutexAutoLock lock(mMutex);
 447   return InitCommon(aDelay, aType, std::move(cb), lock);
 448 }
 449
 450 nsresult nsTimerImpl::InitWithCallback(nsITimerCallback* aCallback,
 451                                        uint32_t aDelayInMs, uint32_t aType) {
 452   return InitHighResolutionWithCallback(
 453       aCallback, TimeDuration::FromMilliseconds(aDelayInMs), aType);
 454 }
 455
 456 nsresult nsTimerImpl::InitHighResolutionWithCallback(
 457     nsITimerCallback* aCallback, const TimeDuration& aDelay, uint32_t aType) {
 458   if (NS_WARN_IF(!aCallback)) {
 459     return NS_ERROR_INVALID_ARG;
 460   }
 461
 462   // Goes out of scope after the unlock, prevents deadlock
 463   Callback cb{nsCOMPtr{aCallback}};
 464
 465   MutexAutoLock lock(mMutex);
 466   return InitCommon(aDelay, aType, std::move(cb), lock);
 467 }
 468
 469 nsresult nsTimerImpl::Init(nsIObserver* aObserver, uint32_t aDelayInMs,
 470                            uint32_t aType) {
 471   if (NS_WARN_IF(!aObserver)) {
 472     return NS_ERROR_INVALID_ARG;
 473   }
 474
 475   Callback cb{nsCOMPtr{aObserver}};
 476
 477   MutexAutoLock lock(mMutex);
 478   return InitCommon(TimeDuration::FromMilliseconds(aDelayInMs), aType,
 479                     std::move(cb), lock);
 480 }
 481
 482 nsresult nsTimerImpl::InitWithClosureCallback(
 483     std::function<void(nsITimer*)>&& aCallback, const TimeDuration& aDelay,
 484     uint32_t aType, const char* aNameString) {
 485   if (NS_WARN_IF(!aCallback)) {
 486     return NS_ERROR_INVALID_ARG;
 487   }
 488
 489   Callback cb{ClosureCallback{std::move(aCallback), aNameString}};
 490
 491   MutexAutoLock lock(mMutex);
 492   return InitCommon(aDelay, aType, std::move(cb), lock);
 493 }
 494
 495 nsresult nsTimerImpl::Cancel() {
 496   CancelImpl(false);
 497   return NS_OK;
 498 }
 499
 500 void nsTimerImpl::CancelImpl(bool aClearITimer) {
 501   Callback cbTrash{UnknownCallback{}};
 502   RefPtr<nsITimer> timerTrash;
 503
 504   {
 505     MutexAutoLock lock(mMutex);
 506     gThreadWrapper.RemoveTimer(this, lock);
 507
 508     // The swap ensures our callback isn't dropped until after the mutex is
 509     // unlocked.
 510     std::swap(cbTrash, mCallback);
 511     ++mGeneration;
 512
 513     // Don't clear this if we're firing; once Fire returns, we'll get this call
 514     // again.
 515     if (aClearITimer && !mFiring) {
 516       MOZ_RELEASE_ASSERT(
 517           mITimer,
 518           "mITimer was nulled already! "
 519           "This indicates that someone has messed up the refcount on nsTimer!");
 520       timerTrash.swap(mITimer);
 521     }
 522   }
 523 }
 524
 525 nsresult nsTimerImpl::SetDelay(uint32_t aDelay) {
 526   MutexAutoLock lock(mMutex);
 527   if (GetCallback().is<UnknownCallback>() && !IsRepeating()) {
 528     // This may happen if someone tries to re-use a one-shot timer
 529     // by re-setting delay instead of reinitializing the timer.
 530     NS_ERROR(
 531         "nsITimer->SetDelay() called when the "
 532         "one-shot timer is not set up.");
 533     return NS_ERROR_NOT_INITIALIZED;
 534   }
 535
 536   bool reAdd = false;
 537   reAdd = NS_SUCCEEDED(gThreadWrapper.RemoveTimer(this, lock));
 538
 539   mDelay = TimeDuration::FromMilliseconds(aDelay);
 540   mTimeout = TimeStamp::Now() + mDelay;
 541
 542   if (reAdd) {
 543     gThreadWrapper.AddTimer(this, lock);
 544   }
 545
 546   return NS_OK;
 547 }
 548
 549 nsresult nsTimerImpl::GetDelay(uint32_t* aDelay) {
 550   MutexAutoLock lock(mMutex);
 551   *aDelay = mDelay.ToMilliseconds();
 552   return NS_OK;
 553 }
 554
 555 nsresult nsTimerImpl::SetType(uint32_t aType) {
 556   MutexAutoLock lock(mMutex);
 557   mType = (uint8_t)aType;
 558   // XXX if this is called, we should change the actual type.. this could effect
 559   // repeating timers.  we need to ensure in Fire() that if mType has changed
 560   // during the callback that we don't end up with the timer in the queue twice.
 561   return NS_OK;
 562 }
 563
 564 nsresult nsTimerImpl::GetType(uint32_t* aType) {
 565   MutexAutoLock lock(mMutex);
 566   *aType = mType;
 567   return NS_OK;
 568 }
 569
 570 nsresult nsTimerImpl::GetClosure(void** aClosure) {
 571   MutexAutoLock lock(mMutex);
 572   if (GetCallback().is<FuncCallback>()) {
 573     *aClosure = GetCallback().as<FuncCallback>().mClosure;
 574   } else {
 575     *aClosure = nullptr;
 576   }
 577   return NS_OK;
 578 }
 579
 580 nsresult nsTimerImpl::GetCallback(nsITimerCallback** aCallback) {
 581   MutexAutoLock lock(mMutex);
 582   if (GetCallback().is<InterfaceCallback>()) {
 583     NS_IF_ADDREF(*aCallback = GetCallback().as<InterfaceCallback>());
 584   } else {
 585     *aCallback = nullptr;
 586   }
 587   return NS_OK;
 588 }
 589
 590 nsresult nsTimerImpl::GetTarget(nsIEventTarget** aTarget) {
 591   MutexAutoLock lock(mMutex);
 592   NS_IF_ADDREF(*aTarget = mEventTarget);
 593   return NS_OK;
 594 }
 595
 596 nsresult nsTimerImpl::SetTarget(nsIEventTarget* aTarget) {
 597   MutexAutoLock lock(mMutex);
 598   if (NS_WARN_IF(!mCallback.is<UnknownCallback>())) {
 599     return NS_ERROR_ALREADY_INITIALIZED;
 600   }
 601
 602   if (aTarget) {
 603     mEventTarget = aTarget;
 604   } else {
 605     mEventTarget = mozilla::GetCurrentSerialEventTarget();
 606   }
 607   return NS_OK;
 608 }
 609
 610 nsresult nsTimerImpl::GetAllowedEarlyFiringMicroseconds(uint32_t* aValueOut) {
 611   *aValueOut = gThreadWrapper.AllowedEarlyFiringMicroseconds();
 612   return NS_OK;
 613 }
 614
 615 void nsTimerImpl::Fire(int32_t aGeneration) {
 616   uint8_t oldType;
 617   uint32_t oldDelay;
 618   TimeStamp oldTimeout;
 619   Callback callbackDuringFire{UnknownCallback{}};
 620   nsCOMPtr<nsITimer> timer;
 621
 622   {
 623     // Don't fire callbacks or fiddle with refcounts when the mutex is locked.
 624     // If some other thread Cancels/Inits after this, they're just too late.
 625     MutexAutoLock lock(mMutex);
 626     if (aGeneration != mGeneration) {
 627       // This timer got rescheduled or cancelled before we fired, so ignore this
 628       // firing
 629       return;
 630     }
 631
 632     // We modify mTimeout, so we must not be in the current TimerThread's
 633     // mTimers list.
 634     MOZ_ASSERT(!mIsInTimerThread);
 635
 636     ++mFiring;
 637     callbackDuringFire = mCallback;
 638     oldType = mType;
 639     oldDelay = mDelay.ToMilliseconds();
 640     oldTimeout = mTimeout;
 641     // Ensure that the nsITimer does not unhook from the nsTimerImpl during
 642     // Fire; this will cause null pointer crashes if the user of the timer drops
 643     // its reference, and then uses the nsITimer* passed in the callback.
 644     timer = mITimer;
 645   }
 646
 647   AUTO_PROFILER_LABEL("nsTimerImpl::Fire", OTHER);
 648
 649   TimeStamp fireTime;
 650   if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
 651     fireTime = TimeStamp::Now();
 652     TimeDuration delta = fireTime - oldTimeout;
 653     int32_t d = delta.ToMilliseconds();  // delta in ms
 654     {
 655       mozilla::StaticMutexAutoLock lock(sDeltaMutex);
 656       sDeltaSum += abs(d);
 657       sDeltaSumSquared += double(d) * double(d);
 658       sDeltaNum++;
 659     }
 660
 661     MOZ_LOG(GetTimerLog(), LogLevel::Debug,
 662             ("[this=%p] expected delay time %4ums\n", this, oldDelay));
 663     MOZ_LOG(GetTimerLog(), LogLevel::Debug,
 664             ("[this=%p] actual delay time   %4dms\n", this, oldDelay + d));
 665     MOZ_LOG(GetTimerLog(), LogLevel::Debug,
 666             ("[this=%p] (mType is %d)       -------\n", this, oldType));
 667     MOZ_LOG(GetTimerLog(), LogLevel::Debug,
 668             ("[this=%p]     delta           %4dms\n", this, d));
 669   }
 670
 671   if (MOZ_LOG_TEST(GetTimerFiringsLog(), LogLevel::Debug)) {
 672     LogFiring(callbackDuringFire, oldType, oldDelay);
 673   }
 674
 675   callbackDuringFire.match(
 676       [](const UnknownCallback&) {},
 677       [&](const InterfaceCallback& i) { i->Notify(timer); },
 678       [&](const ObserverCallback& o) {
 679         o->Observe(timer, NS_TIMER_CALLBACK_TOPIC, nullptr);
 680       },
 681       [&](const FuncCallback& f) { f.mFunc(timer, f.mClosure); },
 682       [&](const ClosureCallback& c) { c.mFunc(timer); });
 683
 684   TimeStamp now = TimeStamp::Now();
 685
 686   MutexAutoLock lock(mMutex);
 687   if (aGeneration == mGeneration) {
 688     if (IsRepeating()) {
 689       // Repeating timer has not been re-init or canceled; reschedule
 690       if (IsSlack()) {
 691         mTimeout = now + mDelay;
 692       } else {
 693         if (mDelay) {
 694           // If we are late enough finishing the callback that we have missed
 695           // some firings, do not attempt to play catchup, just get back on the
 696           // cadence we're supposed to maintain.
 697           unsigned missedFirings =
 698               static_cast<unsigned>((now - mTimeout) / mDelay);
 699           mTimeout += mDelay * (missedFirings + 1);
 700         } else {
 701           // Can we stop allowing repeating timers with delay 0?
 702           mTimeout = now;
 703         }
 704       }
 705       gThreadWrapper.AddTimer(this, lock);
 706     } else {
 707       // Non-repeating timer that has not been re-scheduled. Clear.
 708       // XXX(nika): Other callsites seem to go to some effort to avoid
 709       // destroying mCallback when it's held. Why not this one?
 710       mCallback = mozilla::AsVariant(UnknownCallback{});
 711     }
 712   }
 713
 714   --mFiring;
 715
 716   MOZ_LOG(GetTimerLog(), LogLevel::Debug,
 717           ("[this=%p] Took %fms to fire timer callback\n", this,
 718            (now - fireTime).ToMilliseconds()));
 719 }
 720
 721 // See the big comment above GetTimerFiringsLog() to understand this code.
 722 void nsTimerImpl::LogFiring(const Callback& aCallback, uint8_t aType,
 723                             uint32_t aDelay) {
 724   const char* typeStr;
 725   switch (aType) {
 726     case nsITimer::TYPE_ONE_SHOT:
 727       typeStr = "ONE_SHOT  ";
 728       break;
 729     case nsITimer::TYPE_ONE_SHOT_LOW_PRIORITY:
 730       typeStr = "ONE_LOW   ";
 731       break;
 732     case nsITimer::TYPE_REPEATING_SLACK:
 733       typeStr = "SLACK     ";
 734       break;
 735     case nsITimer::TYPE_REPEATING_SLACK_LOW_PRIORITY:
 736       typeStr = "SLACK_LOW ";
 737       break;
 738     case nsITimer::TYPE_REPEATING_PRECISE: /* fall through */
 739     case nsITimer::TYPE_REPEATING_PRECISE_CAN_SKIP:
 740       typeStr = "PRECISE   ";
 741       break;
 742     default:
 743       MOZ_CRASH("bad type");
 744   }
 745
 746   aCallback.match(
 747       [&](const UnknownCallback&) {
 748         MOZ_LOG(
 749             GetTimerFiringsLog(), LogLevel::Debug,
 750             ("[%d]     ??? timer (%s, %5d ms)\n", getpid(), typeStr, aDelay));
 751       },
 752       [&](const InterfaceCallback& i) {
 753         MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
 754                 ("[%d]   iface timer (%s %5d ms): %p\n", getpid(), typeStr,
 755                  aDelay, i.get()));
 756       },
 757       [&](const ObserverCallback& o) {
 758         MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
 759                 ("[%d]     obs timer (%s %5d ms): %p\n", getpid(), typeStr,
 760                  aDelay, o.get()));
 761       },
 762       [&](const FuncCallback& f) {
 763         MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
 764                 ("[%d]      fn timer (%s %5d ms): %s\n", getpid(), typeStr,
 765                  aDelay, f.mName));
 766       },
 767       [&](const ClosureCallback& c) {
 768         MOZ_LOG(GetTimerFiringsLog(), LogLevel::Debug,
 769                 ("[%d] closure timer (%s %5d ms): %s\n", getpid(), typeStr,
 770                  aDelay, c.mName));
 771       });
 772 }
 773
 774 void nsTimerImpl::GetName(nsACString& aName,
 775                           const MutexAutoLock& aProofOfLock) {
 776   GetCallback().match(
 777       [&](const UnknownCallback&) { aName.AssignLiteral("Canceled_timer"); },
 778       [&](const InterfaceCallback& i) {
 779         if (nsCOMPtr<nsINamed> named = do_QueryInterface(i)) {
 780           named->GetName(aName);
 781         } else {
 782           aName.AssignLiteral("Anonymous_interface_timer");
 783         }
 784       },
 785       [&](const ObserverCallback& o) {
 786         if (nsCOMPtr<nsINamed> named = do_QueryInterface(o)) {
 787           named->GetName(aName);
 788         } else {
 789           aName.AssignLiteral("Anonymous_observer_timer");
 790         }
 791       },
 792       [&](const FuncCallback& f) { aName.Assign(f.mName); },
 793       [&](const ClosureCallback& c) { aName.Assign(c.mName); });
 794 }
 795
 796 nsresult nsTimerImpl::GetName(nsACString& aName) {
 797   MutexAutoLock lock(mMutex);
 798   GetName(aName, lock);
 799   return NS_OK;
 800 }
 801
 802 nsTimer::~nsTimer() = default;
 803
 804 size_t nsTimer::SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) {
 805   return aMallocSizeOf(this);
 806 }
 807
 808 /* static */
 809 RefPtr<nsTimer> nsTimer::WithEventTarget(nsIEventTarget* aTarget) {
 810   if (!aTarget) {
 811     aTarget = mozilla::GetCurrentSerialEventTarget();
 812   }
 813   return do_AddRef(new nsTimer(aTarget));
 814 }
 815
 816 /* static */
 817 nsresult nsTimer::XPCOMConstructor(REFNSIID aIID, void** aResult) {
 818   *aResult = nullptr;
 819   auto timer = WithEventTarget(nullptr);
 820
 821   return timer->QueryInterface(aIID, aResult);
 822 }