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-rw-r--r--xpcom/threads/TimerThread.cpp1565
1 files changed, 1565 insertions, 0 deletions
diff --git a/xpcom/threads/TimerThread.cpp b/xpcom/threads/TimerThread.cpp
new file mode 100644
index 0000000000..d0ff778f20
--- /dev/null
+++ b/xpcom/threads/TimerThread.cpp
@@ -0,0 +1,1565 @@
+/* -*- 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 "GeckoProfiler.h"
+#include "nsThreadUtils.h"
+
+#include "nsIObserverService.h"
+#include "nsIPropertyBag2.h"
+#include "mozilla/Services.h"
+#include "mozilla/ChaosMode.h"
+#include "mozilla/ArenaAllocator.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/OperatorNewExtensions.h"
+#include "mozilla/StaticPrefs_timer.h"
+
+#include "mozilla/glean/GleanMetrics.h"
+
+#include <math.h>
+
+using namespace mozilla;
+
+#ifdef XP_WIN
+// Include Windows header required for enabling high-precision timers.
+# include <windows.h>
+# include <mmsystem.h>
+
+static constexpr UINT kTimerPeriodHiRes = 1;
+static constexpr UINT kTimerPeriodLowRes = 16;
+
+// Helper functions to determine what Windows timer resolution to target.
+static constexpr UINT GetDesiredTimerPeriod(const bool aOnBatteryPower,
+ const bool aLowProcessPriority) {
+ const bool useLowResTimer = aOnBatteryPower || aLowProcessPriority;
+ return useLowResTimer ? kTimerPeriodLowRes : kTimerPeriodHiRes;
+}
+
+static_assert(GetDesiredTimerPeriod(true, false) == kTimerPeriodLowRes);
+static_assert(GetDesiredTimerPeriod(false, true) == kTimerPeriodLowRes);
+static_assert(GetDesiredTimerPeriod(true, true) == kTimerPeriodLowRes);
+static_assert(GetDesiredTimerPeriod(false, false) == kTimerPeriodHiRes);
+
+UINT TimerThread::ComputeDesiredTimerPeriod() const {
+ const bool lowPriorityProcess =
+ mCachedPriority.load(std::memory_order_relaxed) <
+ hal::PROCESS_PRIORITY_FOREGROUND;
+
+ // NOTE: Using short-circuiting here to avoid call to GetSystemPowerStatus()
+ // when we know that that result will not affect the final result. (As
+ // confirmed by the static_assert's above, onBatteryPower does not affect the
+ // result when the lowPriorityProcess is true.)
+ SYSTEM_POWER_STATUS status;
+ const bool onBatteryPower = !lowPriorityProcess &&
+ GetSystemPowerStatus(&status) &&
+ (status.ACLineStatus == 0);
+
+ return GetDesiredTimerPeriod(onBatteryPower, lowPriorityProcess);
+}
+#endif
+
+// Uncomment the following line to enable runtime stats during development.
+// #define TIMERS_RUNTIME_STATS
+
+#ifdef TIMERS_RUNTIME_STATS
+// This class gathers durations and displays some basic stats when destroyed.
+// It is intended to be used as a static variable (see `AUTO_TIMERS_STATS`
+// below), to display stats at the end of the program.
+class StaticTimersStats {
+ public:
+ explicit StaticTimersStats(const char* aName) : mName(aName) {}
+
+ ~StaticTimersStats() {
+ // Using unsigned long long for computations and printfs.
+ using ULL = unsigned long long;
+ ULL n = static_cast<ULL>(mCount);
+ if (n == 0) {
+ printf("[%d] Timers stats `%s`: (nothing)\n",
+ int(profiler_current_process_id().ToNumber()), mName);
+ } else if (ULL sumNs = static_cast<ULL>(mSumDurationsNs); sumNs == 0) {
+ printf("[%d] Timers stats `%s`: %llu\n",
+ int(profiler_current_process_id().ToNumber()), mName, n);
+ } else {
+ printf("[%d] Timers stats `%s`: %llu ns / %llu = %llu ns, max %llu ns\n",
+ int(profiler_current_process_id().ToNumber()), mName, sumNs, n,
+ sumNs / n, static_cast<ULL>(mLongestDurationNs));
+ }
+ }
+
+ void AddDurationFrom(TimeStamp aStart) {
+ // Duration between aStart and now, rounded to the nearest nanosecond.
+ DurationNs duration = static_cast<DurationNs>(
+ (TimeStamp::Now() - aStart).ToMicroseconds() * 1000 + 0.5);
+ mSumDurationsNs += duration;
+ ++mCount;
+ // Update mLongestDurationNs if this one is longer.
+ for (;;) {
+ DurationNs longest = mLongestDurationNs;
+ if (MOZ_LIKELY(longest >= duration)) {
+ // This duration is not the longest, nothing to do.
+ break;
+ }
+ if (MOZ_LIKELY(mLongestDurationNs.compareExchange(longest, duration))) {
+ // Successfully updated `mLongestDurationNs` with the new value.
+ break;
+ }
+ // Otherwise someone else just updated `mLongestDurationNs`, we need to
+ // try again by looping.
+ }
+ }
+
+ void AddCount() {
+ MOZ_ASSERT(mSumDurationsNs == 0, "Don't mix counts and durations");
+ ++mCount;
+ }
+
+ private:
+ using DurationNs = uint64_t;
+ using Count = uint32_t;
+
+ Atomic<DurationNs> mSumDurationsNs{0};
+ Atomic<DurationNs> mLongestDurationNs{0};
+ Atomic<Count> mCount{0};
+ const char* mName;
+};
+
+// RAII object that measures its scoped lifetime duration and reports it to a
+// `StaticTimersStats`.
+class MOZ_RAII AutoTimersStats {
+ public:
+ explicit AutoTimersStats(StaticTimersStats& aStats)
+ : mStats(aStats), mStart(TimeStamp::Now()) {}
+
+ ~AutoTimersStats() { mStats.AddDurationFrom(mStart); }
+
+ private:
+ StaticTimersStats& mStats;
+ TimeStamp mStart;
+};
+
+// Macro that should be used to collect basic statistics from measurements of
+// block durations, from where this macro is, until the end of its enclosing
+// scope. The name is used in the static variable name and when displaying stats
+// at the end of the program; Another location could use the same name but their
+// stats will not be combined, so use different name if these locations should
+// be distinguished.
+# define AUTO_TIMERS_STATS(name) \
+ static ::StaticTimersStats sStat##name(#name); \
+ ::AutoTimersStats autoStat##name(sStat##name);
+
+// This macro only counts the number of times it's used, not durations.
+// Don't mix with AUTO_TIMERS_STATS!
+# define COUNT_TIMERS_STATS(name) \
+ static ::StaticTimersStats sStat##name(#name); \
+ sStat##name.AddCount();
+
+#else // TIMERS_RUNTIME_STATS
+
+# define AUTO_TIMERS_STATS(name)
+# define COUNT_TIMERS_STATS(name)
+
+#endif // TIMERS_RUNTIME_STATS else
+
+NS_IMPL_ISUPPORTS_INHERITED(TimerThread, Runnable, nsIObserver)
+
+TimerThread::TimerThread()
+ : Runnable("TimerThread"),
+ mInitialized(false),
+ mMonitor("TimerThread.mMonitor"),
+ mShutdown(false),
+ mWaiting(false),
+ mNotified(false),
+ mSleeping(false),
+ mAllowedEarlyFiringMicroseconds(0) {}
+
+TimerThread::~TimerThread() {
+ mThread = nullptr;
+
+ NS_ASSERTION(mTimers.IsEmpty(), "Timers remain in TimerThread::~TimerThread");
+
+#if TIMER_THREAD_STATISTICS
+ {
+ MonitorAutoLock lock(mMonitor);
+ PrintStatistics();
+ }
+#endif
+}
+
+namespace {
+
+class TimerObserverRunnable : public Runnable {
+ public:
+ explicit TimerObserverRunnable(nsIObserver* aObserver)
+ : mozilla::Runnable("TimerObserverRunnable"), mObserver(aObserver) {}
+
+ NS_DECL_NSIRUNNABLE
+
+ private:
+ nsCOMPtr<nsIObserver> mObserver;
+};
+
+NS_IMETHODIMP
+TimerObserverRunnable::Run() {
+ nsCOMPtr<nsIObserverService> observerService =
+ mozilla::services::GetObserverService();
+ if (observerService) {
+ observerService->AddObserver(mObserver, "sleep_notification", false);
+ observerService->AddObserver(mObserver, "wake_notification", false);
+ observerService->AddObserver(mObserver, "suspend_process_notification",
+ false);
+ observerService->AddObserver(mObserver, "resume_process_notification",
+ false);
+ observerService->AddObserver(mObserver, "ipc:process-priority-changed",
+ false);
+ }
+ return NS_OK;
+}
+
+} // namespace
+
+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 is layered over ArenaAllocator, 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;
+ };
+
+ ArenaAllocator<4096> mPool MOZ_GUARDED_BY(mMonitor);
+ FreeEntry* mFirstFree MOZ_GUARDED_BY(mMonitor);
+ mozilla::Monitor mMonitor;
+
+ public:
+ TimerEventAllocator()
+ : mFirstFree(nullptr), mMonitor("TimerEventAllocator") {}
+
+ ~TimerEventAllocator() = default;
+
+ void* Alloc(size_t aSize);
+ void Free(void* aPtr);
+};
+
+} // namespace
+
+// This is a nsICancelableRunnable because we can dispatch it to Workers and
+// those can be shut down at any time, and in these cases, Cancel() is called
+// instead of Run().
+class nsTimerEvent final : public CancelableRunnable {
+ public:
+ NS_IMETHOD Run() override;
+
+ nsresult Cancel() override {
+ mTimer->Cancel();
+ return NS_OK;
+ }
+
+#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
+ NS_IMETHOD GetName(nsACString& aName) override;
+#endif
+
+ explicit nsTimerEvent(already_AddRefed<nsTimerImpl> aTimer,
+ ProfilerThreadId aTimerThreadId)
+ : mozilla::CancelableRunnable("nsTimerEvent"),
+ mTimer(aTimer),
+ mGeneration(mTimer->GetGeneration()),
+ mTimerThreadId(aTimerThreadId) {
+ // Note: We override operator new for this class, and the override is
+ // fallible!
+ sAllocatorUsers++;
+
+ if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug) ||
+ profiler_thread_is_being_profiled_for_markers(mTimerThreadId)) {
+ mInitTime = TimeStamp::Now();
+ }
+ }
+
+ static void Init();
+ static void Shutdown();
+ static void DeleteAllocatorIfNeeded();
+
+ static void* operator new(size_t aSize) noexcept(true) {
+ return sAllocator->Alloc(aSize);
+ }
+ void operator delete(void* aPtr) {
+ sAllocator->Free(aPtr);
+ sAllocatorUsers--;
+ DeleteAllocatorIfNeeded();
+ }
+
+ already_AddRefed<nsTimerImpl> ForgetTimer() { return mTimer.forget(); }
+
+ private:
+ nsTimerEvent(const nsTimerEvent&) = delete;
+ nsTimerEvent& operator=(const nsTimerEvent&) = delete;
+ nsTimerEvent& operator=(const nsTimerEvent&&) = delete;
+
+ ~nsTimerEvent() {
+ MOZ_ASSERT(!sCanDeleteAllocator || sAllocatorUsers > 0,
+ "This will result in us attempting to deallocate the "
+ "nsTimerEvent allocator twice");
+ }
+
+ TimeStamp mInitTime;
+ RefPtr<nsTimerImpl> mTimer;
+ const int32_t mGeneration;
+ ProfilerThreadId mTimerThreadId;
+
+ static TimerEventAllocator* sAllocator;
+
+ static Atomic<int32_t, SequentiallyConsistent> sAllocatorUsers;
+ static Atomic<bool, SequentiallyConsistent> sCanDeleteAllocator;
+};
+
+TimerEventAllocator* nsTimerEvent::sAllocator = nullptr;
+Atomic<int32_t, SequentiallyConsistent> nsTimerEvent::sAllocatorUsers;
+Atomic<bool, SequentiallyConsistent> nsTimerEvent::sCanDeleteAllocator;
+
+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 {
+ p = mPool.Allocate(aSize, fallible);
+ }
+
+ return p;
+}
+
+void TimerEventAllocator::Free(void* aPtr) {
+ mozilla::MonitorAutoLock lock(mMonitor);
+
+ FreeEntry* entry = reinterpret_cast<FreeEntry*>(aPtr);
+
+ entry->mNext = mFirstFree;
+ mFirstFree = entry;
+}
+
+} // namespace
+
+struct TimerMarker {
+ static constexpr Span<const char> MarkerTypeName() {
+ return MakeStringSpan("Timer");
+ }
+ static void StreamJSONMarkerData(baseprofiler::SpliceableJSONWriter& aWriter,
+ uint32_t aDelay, uint8_t aType,
+ MarkerThreadId aThreadId, bool aCanceled) {
+ aWriter.IntProperty("delay", aDelay);
+ if (!aThreadId.IsUnspecified()) {
+ // Tech note: If `ToNumber()` returns a uint64_t, the conversion to
+ // int64_t is "implementation-defined" before C++20. This is
+ // acceptable here, because this is a one-way conversion to a unique
+ // identifier that's used to visually separate data by thread on the
+ // front-end.
+ aWriter.IntProperty(
+ "threadId", static_cast<int64_t>(aThreadId.ThreadId().ToNumber()));
+ }
+ if (aCanceled) {
+ aWriter.BoolProperty("canceled", true);
+ // Show a red 'X' as a prefix on the marker chart for canceled timers.
+ aWriter.StringProperty("prefix", "❌");
+ }
+
+ // The string property for the timer type is not written when the type is
+ // one shot, as that's the type used almost all the time, and that would
+ // consume space in the profiler buffer and then in the profile JSON,
+ // getting in the way of capturing long power profiles.
+ // Bug 1815677 might make this cheap to capture.
+ if (aType != nsITimer::TYPE_ONE_SHOT) {
+ if (aType == nsITimer::TYPE_REPEATING_SLACK) {
+ aWriter.StringProperty("ttype", "repeating slack");
+ } else if (aType == nsITimer::TYPE_REPEATING_PRECISE) {
+ aWriter.StringProperty("ttype", "repeating precise");
+ } else if (aType == nsITimer::TYPE_REPEATING_PRECISE_CAN_SKIP) {
+ aWriter.StringProperty("ttype", "repeating precise can skip");
+ } else if (aType == nsITimer::TYPE_REPEATING_SLACK_LOW_PRIORITY) {
+ aWriter.StringProperty("ttype", "repeating slack low priority");
+ } else if (aType == nsITimer::TYPE_ONE_SHOT_LOW_PRIORITY) {
+ aWriter.StringProperty("ttype", "low priority");
+ }
+ }
+ }
+ static MarkerSchema MarkerTypeDisplay() {
+ using MS = MarkerSchema;
+ MS schema{MS::Location::MarkerChart, MS::Location::MarkerTable};
+ schema.AddKeyLabelFormat("delay", "Delay", MS::Format::Milliseconds);
+ schema.AddKeyLabelFormat("ttype", "Timer Type", MS::Format::String);
+ schema.AddKeyLabelFormat("canceled", "Canceled", MS::Format::String);
+ schema.SetChartLabel("{marker.data.prefix} {marker.data.delay}");
+ schema.SetTableLabel(
+ "{marker.name} - {marker.data.prefix} {marker.data.delay}");
+ return schema;
+ }
+};
+
+struct AddRemoveTimerMarker {
+ static constexpr Span<const char> MarkerTypeName() {
+ return MakeStringSpan("AddRemoveTimer");
+ }
+ static void StreamJSONMarkerData(baseprofiler::SpliceableJSONWriter& aWriter,
+ const ProfilerString8View& aTimerName,
+ uint32_t aDelay, MarkerThreadId aThreadId) {
+ aWriter.StringProperty("name", aTimerName);
+ aWriter.IntProperty("delay", aDelay);
+ if (!aThreadId.IsUnspecified()) {
+ // Tech note: If `ToNumber()` returns a uint64_t, the conversion to
+ // int64_t is "implementation-defined" before C++20. This is
+ // acceptable here, because this is a one-way conversion to a unique
+ // identifier that's used to visually separate data by thread on the
+ // front-end.
+ aWriter.IntProperty(
+ "threadId", static_cast<int64_t>(aThreadId.ThreadId().ToNumber()));
+ }
+ }
+ static MarkerSchema MarkerTypeDisplay() {
+ using MS = MarkerSchema;
+ MS schema{MS::Location::MarkerChart, MS::Location::MarkerTable};
+ schema.AddKeyLabelFormatSearchable("name", "Name", MS::Format::String,
+ MS::Searchable::Searchable);
+ schema.AddKeyLabelFormat("delay", "Delay", MS::Format::Milliseconds);
+ schema.SetTableLabel(
+ "{marker.name} - {marker.data.name} - {marker.data.delay}");
+ return schema;
+ }
+};
+
+void nsTimerEvent::Init() { sAllocator = new TimerEventAllocator(); }
+
+void nsTimerEvent::Shutdown() {
+ sCanDeleteAllocator = true;
+ DeleteAllocatorIfNeeded();
+}
+
+void nsTimerEvent::DeleteAllocatorIfNeeded() {
+ if (sCanDeleteAllocator && sAllocatorUsers == 0) {
+ delete sAllocator;
+ sAllocator = nullptr;
+ }
+}
+
+#ifdef MOZ_COLLECTING_RUNNABLE_TELEMETRY
+NS_IMETHODIMP
+nsTimerEvent::GetName(nsACString& aName) {
+ bool current;
+ MOZ_RELEASE_ASSERT(
+ NS_SUCCEEDED(mTimer->mEventTarget->IsOnCurrentThread(&current)) &&
+ current);
+
+ mTimer->GetName(aName);
+ return NS_OK;
+}
+#endif
+
+NS_IMETHODIMP
+nsTimerEvent::Run() {
+ if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
+ TimeStamp now = TimeStamp::Now();
+ MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+ ("[this=%p] time between PostTimerEvent() and Fire(): %fms\n", this,
+ (now - mInitTime).ToMilliseconds()));
+ }
+
+ if (profiler_thread_is_being_profiled_for_markers(mTimerThreadId)) {
+ MutexAutoLock lock(mTimer->mMutex);
+ nsAutoCString name;
+ mTimer->GetName(name, lock);
+ // This adds a marker with the timer name as the marker name, to make it
+ // obvious which timers are being used. This marker will be useful to
+ // understand which timers might be added and firing excessively often.
+ profiler_add_marker(
+ name, geckoprofiler::category::TIMER,
+ MarkerOptions(MOZ_LIKELY(mInitTime)
+ ? MarkerTiming::Interval(
+ mTimer->mTimeout - mTimer->mDelay, mInitTime)
+ : MarkerTiming::IntervalUntilNowFrom(
+ mTimer->mTimeout - mTimer->mDelay),
+ MarkerThreadId(mTimerThreadId)),
+ TimerMarker{}, mTimer->mDelay.ToMilliseconds(), mTimer->mType,
+ MarkerThreadId::CurrentThread(), false);
+ // This marker is meant to help understand the behavior of the timer thread.
+ profiler_add_marker(
+ "PostTimerEvent", geckoprofiler::category::OTHER,
+ MarkerOptions(MOZ_LIKELY(mInitTime)
+ ? MarkerTiming::IntervalUntilNowFrom(mInitTime)
+ : MarkerTiming::InstantNow(),
+ MarkerThreadId(mTimerThreadId)),
+ AddRemoveTimerMarker{}, name, mTimer->mDelay.ToMilliseconds(),
+ MarkerThreadId::CurrentThread());
+ }
+
+ mTimer->Fire(mGeneration);
+
+ return NS_OK;
+}
+
+nsresult TimerThread::Init() {
+ mMonitor.AssertCurrentThreadOwns();
+ MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+ ("TimerThread::Init [%d]\n", mInitialized));
+
+ if (!mInitialized) {
+ nsTimerEvent::Init();
+
+ // We hold on to mThread to keep the thread alive.
+ nsresult rv =
+ NS_NewNamedThread("Timer", getter_AddRefs(mThread), this,
+ {.stackSize = nsIThreadManager::DEFAULT_STACK_SIZE,
+ .blockDispatch = true});
+ if (NS_FAILED(rv)) {
+ mThread = nullptr;
+ } else {
+ RefPtr<TimerObserverRunnable> r = new TimerObserverRunnable(this);
+ if (NS_IsMainThread()) {
+ r->Run();
+ } else {
+ NS_DispatchToMainThread(r);
+ }
+ }
+
+ mInitialized = true;
+ }
+
+ if (!mThread) {
+ return NS_ERROR_FAILURE;
+ }
+
+ return NS_OK;
+}
+
+nsresult TimerThread::Shutdown() {
+ MOZ_LOG(GetTimerLog(), LogLevel::Debug, ("TimerThread::Shutdown begin\n"));
+
+ if (!mThread) {
+ return NS_ERROR_NOT_INITIALIZED;
+ }
+
+ nsTArray<RefPtr<nsTimerImpl>> timers;
+ {
+ // lock scope
+ MonitorAutoLock lock(mMonitor);
+
+ mShutdown = true;
+
+ // notify the cond var so that Run() can return
+ if (mWaiting) {
+ mNotified = true;
+ mMonitor.Notify();
+ }
+
+ // Need to copy content of mTimers array to a local array
+ // because call to timers' Cancel() (and release its self)
+ // must not be done under the lock. Destructor of a callback
+ // might potentially call some code reentering the same lock
+ // that leads to unexpected behavior or deadlock.
+ // See bug 422472.
+ timers.SetCapacity(mTimers.Length());
+ for (Entry& entry : mTimers) {
+ if (entry.Value()) {
+ timers.AppendElement(entry.Take());
+ }
+ }
+
+ mTimers.Clear();
+ }
+
+ for (const RefPtr<nsTimerImpl>& timer : timers) {
+ MOZ_ASSERT(timer);
+ timer->Cancel();
+ }
+
+ mThread->Shutdown(); // wait for the thread to die
+
+ nsTimerEvent::Shutdown();
+
+ MOZ_LOG(GetTimerLog(), LogLevel::Debug, ("TimerThread::Shutdown end\n"));
+ return NS_OK;
+}
+
+namespace {
+
+struct MicrosecondsToInterval {
+ PRIntervalTime operator[](size_t aMs) const {
+ return PR_MicrosecondsToInterval(aMs);
+ }
+};
+
+struct IntervalComparator {
+ int operator()(PRIntervalTime aInterval) const {
+ return (0 < aInterval) ? -1 : 1;
+ }
+};
+
+} // namespace
+
+#ifdef DEBUG
+void TimerThread::VerifyTimerListConsistency() const {
+ mMonitor.AssertCurrentThreadOwns();
+
+ // Find the first non-canceled timer (and check its cached timeout if we find
+ // it).
+ const size_t timerCount = mTimers.Length();
+ size_t lastNonCanceledTimerIndex = 0;
+ while (lastNonCanceledTimerIndex < timerCount &&
+ !mTimers[lastNonCanceledTimerIndex].Value()) {
+ ++lastNonCanceledTimerIndex;
+ }
+ MOZ_ASSERT(lastNonCanceledTimerIndex == timerCount ||
+ mTimers[lastNonCanceledTimerIndex].Value());
+ MOZ_ASSERT(lastNonCanceledTimerIndex == timerCount ||
+ mTimers[lastNonCanceledTimerIndex].Value()->mTimeout ==
+ mTimers[lastNonCanceledTimerIndex].Timeout());
+
+ // Verify that mTimers is sorted and the cached timeouts are consistent.
+ for (size_t timerIndex = lastNonCanceledTimerIndex + 1;
+ timerIndex < timerCount; ++timerIndex) {
+ if (mTimers[timerIndex].Value()) {
+ MOZ_ASSERT(mTimers[timerIndex].Timeout() ==
+ mTimers[timerIndex].Value()->mTimeout);
+ MOZ_ASSERT(mTimers[timerIndex].Timeout() >=
+ mTimers[lastNonCanceledTimerIndex].Timeout());
+ lastNonCanceledTimerIndex = timerIndex;
+ }
+ }
+}
+#endif
+
+size_t TimerThread::ComputeTimerInsertionIndex(const TimeStamp& timeout) const {
+ mMonitor.AssertCurrentThreadOwns();
+
+ const size_t timerCount = mTimers.Length();
+
+ size_t firstGtIndex = 0;
+ while (firstGtIndex < timerCount &&
+ (!mTimers[firstGtIndex].Value() ||
+ mTimers[firstGtIndex].Timeout() <= timeout)) {
+ ++firstGtIndex;
+ }
+
+ return firstGtIndex;
+}
+
+TimeStamp TimerThread::ComputeWakeupTimeFromTimers() const {
+ mMonitor.AssertCurrentThreadOwns();
+
+ // Timer list should be non-empty and first timer should always be
+ // non-canceled at this point and we rely on that here.
+ MOZ_ASSERT(!mTimers.IsEmpty());
+ MOZ_ASSERT(mTimers[0].Value());
+
+ // Overview: Find the last timer in the list that can be "bundled" together in
+ // the same wake-up with mTimers[0] and use its timeout as our target wake-up
+ // time.
+
+ // bundleWakeup is when we should wake up in order to be able to fire all of
+ // the timers in our selected bundle. It will always be the timeout of the
+ // last timer in the bundle.
+ TimeStamp bundleWakeup = mTimers[0].Timeout();
+
+ // cutoffTime is the latest that we can wake up for the timers currently
+ // accepted into the bundle. These needs to be updated as we go through the
+ // list because later timers may have more strict delay tolerances.
+ const TimeDuration minTimerDelay = TimeDuration::FromMilliseconds(
+ StaticPrefs::timer_minimum_firing_delay_tolerance_ms());
+ const TimeDuration maxTimerDelay = TimeDuration::FromMilliseconds(
+ StaticPrefs::timer_maximum_firing_delay_tolerance_ms());
+ TimeStamp cutoffTime =
+ bundleWakeup + ComputeAcceptableFiringDelay(mTimers[0].Delay(),
+ minTimerDelay, maxTimerDelay);
+
+ const size_t timerCount = mTimers.Length();
+ for (size_t entryIndex = 1; entryIndex < timerCount; ++entryIndex) {
+ const Entry& curEntry = mTimers[entryIndex];
+ const nsTimerImpl* curTimer = curEntry.Value();
+ if (!curTimer) {
+ // Canceled timer - skip it
+ continue;
+ }
+
+ const TimeStamp curTimerDue = curEntry.Timeout();
+ if (curTimerDue > cutoffTime) {
+ // Can't include this timer in the bundle - it fires too late.
+ break;
+ }
+
+ // This timer can be included in the bundle. Update bundleWakeup and
+ // cutoffTime.
+ bundleWakeup = curTimerDue;
+ cutoffTime = std::min(
+ curTimerDue + ComputeAcceptableFiringDelay(
+ curEntry.Delay(), minTimerDelay, maxTimerDelay),
+ cutoffTime);
+ MOZ_ASSERT(bundleWakeup <= cutoffTime);
+ }
+
+#if !defined(XP_WIN)
+ // Due to the fact that, on Windows, each TimeStamp object holds two distinct
+ // "values", this assert is not valid there. See bug 1829983 for the details.
+ MOZ_ASSERT(bundleWakeup - mTimers[0].Timeout() <=
+ ComputeAcceptableFiringDelay(mTimers[0].Delay(), minTimerDelay,
+ maxTimerDelay));
+#endif
+
+ return bundleWakeup;
+}
+
+TimeDuration TimerThread::ComputeAcceptableFiringDelay(
+ TimeDuration timerDuration, TimeDuration minDelay,
+ TimeDuration maxDelay) const {
+ // Use the timer's duration divided by this value as a base for how much
+ // firing delay a timer can accept. 8 was chosen specifically because it is a
+ // power of two which means that this division turns nicely into a shift.
+ constexpr int64_t timerDurationDivider = 8;
+ static_assert(IsPowerOfTwo(static_cast<uint64_t>(timerDurationDivider)));
+ const TimeDuration tmp = timerDuration / timerDurationDivider;
+ return std::min(std::max(minDelay, tmp), maxDelay);
+}
+
+NS_IMETHODIMP
+TimerThread::Run() {
+ MonitorAutoLock lock(mMonitor);
+
+ mProfilerThreadId = profiler_current_thread_id();
+
+ // TODO: Make mAllowedEarlyFiringMicroseconds const and initialize it in the
+ // constructor.
+ mAllowedEarlyFiringMicroseconds = 250;
+ const TimeDuration allowedEarlyFiring =
+ TimeDuration::FromMicroseconds(mAllowedEarlyFiringMicroseconds);
+
+ bool forceRunNextTimer = false;
+
+ // Queue for tracking of how many timers are fired on each wake-up. We need to
+ // buffer these locally and only send off to glean occasionally to avoid
+ // performance hit.
+ static constexpr size_t kMaxQueuedTimerFired = 128;
+ size_t queuedTimerFiredCount = 0;
+ AutoTArray<uint64_t, kMaxQueuedTimerFired> queuedTimersFiredPerWakeup;
+ queuedTimersFiredPerWakeup.SetLengthAndRetainStorage(kMaxQueuedTimerFired);
+
+#ifdef XP_WIN
+ // kTimerPeriodEvalIntervalSec is the minimum amount of time that must pass
+ // before we will consider changing the timer period again.
+ static constexpr float kTimerPeriodEvalIntervalSec = 2.0f;
+ const TimeDuration timerPeriodEvalInterval =
+ TimeDuration::FromSeconds(kTimerPeriodEvalIntervalSec);
+ TimeStamp nextTimerPeriodEval = TimeStamp::Now() + timerPeriodEvalInterval;
+
+ // If this is false, we will perform all of the logic but will stop short of
+ // actually changing the timer period.
+ const bool adjustTimerPeriod =
+ StaticPrefs::timer_auto_increase_timer_resolution();
+ UINT lastTimePeriodSet = ComputeDesiredTimerPeriod();
+
+ if (adjustTimerPeriod) {
+ timeBeginPeriod(lastTimePeriodSet);
+ }
+#endif
+
+ uint64_t timersFiredThisWakeup = 0;
+ while (!mShutdown) {
+ // Have to use PRIntervalTime here, since PR_WaitCondVar takes it
+ TimeDuration waitFor;
+ bool forceRunThisTimer = forceRunNextTimer;
+ forceRunNextTimer = false;
+
+#ifdef DEBUG
+ VerifyTimerListConsistency();
+#endif
+
+ if (mSleeping) {
+ // Sleep for 0.1 seconds while not firing timers.
+ uint32_t milliseconds = 100;
+ if (ChaosMode::isActive(ChaosFeature::TimerScheduling)) {
+ milliseconds = ChaosMode::randomUint32LessThan(200);
+ }
+ waitFor = TimeDuration::FromMilliseconds(milliseconds);
+ } else {
+ waitFor = TimeDuration::Forever();
+ TimeStamp now = TimeStamp::Now();
+
+#ifdef XP_WIN
+ if (now >= nextTimerPeriodEval) {
+ const UINT newTimePeriod = ComputeDesiredTimerPeriod();
+ if (newTimePeriod != lastTimePeriodSet) {
+ if (adjustTimerPeriod) {
+ timeEndPeriod(lastTimePeriodSet);
+ timeBeginPeriod(newTimePeriod);
+ }
+ lastTimePeriodSet = newTimePeriod;
+ }
+ nextTimerPeriodEval = now + timerPeriodEvalInterval;
+ }
+#endif
+
+#if TIMER_THREAD_STATISTICS
+ if (!mNotified && !mIntendedWakeupTime.IsNull() &&
+ now < mIntendedWakeupTime) {
+ ++mEarlyWakeups;
+ const double earlinessms = (mIntendedWakeupTime - now).ToMilliseconds();
+ mTotalEarlyWakeupTime += earlinessms;
+ }
+#endif
+
+ RemoveLeadingCanceledTimersInternal();
+
+ if (!mTimers.IsEmpty()) {
+ if (now + allowedEarlyFiring >= mTimers[0].Value()->mTimeout ||
+ forceRunThisTimer) {
+ next:
+ // NB: AddRef before the Release under RemoveTimerInternal to avoid
+ // mRefCnt passing through zero, in case all other refs than the one
+ // from mTimers have gone away (the last non-mTimers[i]-ref's Release
+ // must be racing with us, blocked in gThread->RemoveTimer waiting
+ // for TimerThread::mMonitor, under nsTimerImpl::Release.
+
+ RefPtr<nsTimerImpl> timerRef(mTimers[0].Take());
+ RemoveFirstTimerInternal();
+ MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+ ("Timer thread woke up %fms from when it was supposed to\n",
+ fabs((now - timerRef->mTimeout).ToMilliseconds())));
+
+ // We are going to let the call to PostTimerEvent here handle the
+ // release of the timer so that we don't end up releasing the timer
+ // on the TimerThread instead of on the thread it targets.
+ {
+ ++timersFiredThisWakeup;
+ LogTimerEvent::Run run(timerRef.get());
+ PostTimerEvent(timerRef.forget());
+ }
+
+ if (mShutdown) {
+ break;
+ }
+
+ // Update now, as PostTimerEvent plus the locking may have taken a
+ // tick or two, and we may goto next below.
+ now = TimeStamp::Now();
+ }
+ }
+
+ RemoveLeadingCanceledTimersInternal();
+
+ if (!mTimers.IsEmpty()) {
+ TimeStamp timeout = mTimers[0].Value()->mTimeout;
+
+ // Don't wait at all (even for PR_INTERVAL_NO_WAIT) if the next timer
+ // is due now or overdue.
+ //
+ // Note that we can only sleep for integer values of a certain
+ // resolution. We use mAllowedEarlyFiringMicroseconds, calculated
+ // before, to do the optimal rounding (i.e., of how to decide what
+ // interval is so small we should not wait at all).
+ double microseconds = (timeout - now).ToMicroseconds();
+
+ // The mean value of sFractions must be 1 to ensure that the average of
+ // a long sequence of timeouts converges to the actual sum of their
+ // times.
+ static constexpr double sChaosFractions[] = {0.0, 0.25, 0.5, 0.75,
+ 1.0, 1.75, 2.75};
+ if (ChaosMode::isActive(ChaosFeature::TimerScheduling)) {
+ microseconds *= sChaosFractions[ChaosMode::randomUint32LessThan(
+ ArrayLength(sChaosFractions))];
+ forceRunNextTimer = true;
+ }
+
+ if (microseconds < mAllowedEarlyFiringMicroseconds) {
+ forceRunNextTimer = false;
+ goto next; // round down; execute event now
+ }
+
+ // TECHNICAL NOTE: Determining waitFor (by subtracting |now| from our
+ // desired wake-up time) at this point is not ideal. For one thing, the
+ // |now| that we have at this point is somewhat old. Secondly, there is
+ // quite a bit of code between here and where we actually use waitFor to
+ // request sleep. If I am thinking about this correctly, both of these
+ // will contribute to us requesting more sleep than is actually needed
+ // to wake up at our desired time. We could avoid this problem by only
+ // determining our desired wake-up time here and then calculating the
+ // wait time when we're actually about to sleep.
+ const TimeStamp wakeupTime = ComputeWakeupTimeFromTimers();
+ waitFor = wakeupTime - now;
+
+ // If this were to fail that would mean that we had more timers that we
+ // should have fired.
+ MOZ_ASSERT(!waitFor.IsZero());
+
+ if (ChaosMode::isActive(ChaosFeature::TimerScheduling)) {
+ // If chaos mode is active then mess with the amount of time that we
+ // request to sleep (without changing what we record as our expected
+ // wake-up time). This will simulate unintended early/late wake-ups.
+ const double waitInMs = waitFor.ToMilliseconds();
+ const double chaosWaitInMs =
+ waitInMs * sChaosFractions[ChaosMode::randomUint32LessThan(
+ ArrayLength(sChaosFractions))];
+ waitFor = TimeDuration::FromMilliseconds(chaosWaitInMs);
+ }
+
+ mIntendedWakeupTime = wakeupTime;
+ } else {
+ mIntendedWakeupTime = TimeStamp{};
+ }
+
+ if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
+ if (waitFor == TimeDuration::Forever())
+ MOZ_LOG(GetTimerLog(), LogLevel::Debug, ("waiting forever\n"));
+ else
+ MOZ_LOG(GetTimerLog(), LogLevel::Debug,
+ ("waiting for %f\n", waitFor.ToMilliseconds()));
+ }
+ }
+
+ {
+ // About to sleep - let's make note of how many timers we processed and
+ // see if we should send out a new batch of telemetry.
+ queuedTimersFiredPerWakeup[queuedTimerFiredCount] = timersFiredThisWakeup;
+ ++queuedTimerFiredCount;
+ if (queuedTimerFiredCount == kMaxQueuedTimerFired) {
+ glean::timer_thread::timers_fired_per_wakeup.AccumulateSamples(
+ queuedTimersFiredPerWakeup);
+ queuedTimerFiredCount = 0;
+ }
+ }
+
+#if TIMER_THREAD_STATISTICS
+ {
+ size_t bucketIndex = 0;
+ while (bucketIndex < sTimersFiredPerWakeupBucketCount - 1 &&
+ timersFiredThisWakeup >
+ sTimersFiredPerWakeupThresholds[bucketIndex]) {
+ ++bucketIndex;
+ }
+ MOZ_ASSERT(bucketIndex < sTimersFiredPerWakeupBucketCount);
+ ++mTimersFiredPerWakeup[bucketIndex];
+
+ ++mTotalWakeupCount;
+ if (mNotified) {
+ ++mTimersFiredPerNotifiedWakeup[bucketIndex];
+ ++mTotalNotifiedWakeupCount;
+ } else {
+ ++mTimersFiredPerUnnotifiedWakeup[bucketIndex];
+ ++mTotalUnnotifiedWakeupCount;
+ }
+ }
+#endif
+
+ timersFiredThisWakeup = 0;
+
+ mWaiting = true;
+ mNotified = false;
+
+ {
+ AUTO_PROFILER_TRACING_MARKER("TimerThread", "Wait", OTHER);
+ mMonitor.Wait(waitFor);
+ }
+ if (mNotified) {
+ forceRunNextTimer = false;
+ }
+ mWaiting = false;
+ }
+
+ // About to shut down - let's send out the final batch of timers fired counts.
+ if (queuedTimerFiredCount != 0) {
+ queuedTimersFiredPerWakeup.SetLengthAndRetainStorage(queuedTimerFiredCount);
+ glean::timer_thread::timers_fired_per_wakeup.AccumulateSamples(
+ queuedTimersFiredPerWakeup);
+ }
+
+#ifdef XP_WIN
+ // About to shut down - let's finish off the last time period that we set.
+ if (adjustTimerPeriod) {
+ timeEndPeriod(lastTimePeriodSet);
+ }
+#endif
+
+ return NS_OK;
+}
+
+nsresult TimerThread::AddTimer(nsTimerImpl* aTimer,
+ const MutexAutoLock& aProofOfLock) {
+ MonitorAutoLock lock(mMonitor);
+ AUTO_TIMERS_STATS(TimerThread_AddTimer);
+
+ if (!aTimer->mEventTarget) {
+ return NS_ERROR_NOT_INITIALIZED;
+ }
+
+ nsresult rv = Init();
+ if (NS_FAILED(rv)) {
+ return rv;
+ }
+
+ // Awaken the timer thread if:
+ // - This timer needs to fire *before* the Timer Thread is scheduled to wake
+ // up.
+ // AND/OR
+ // - The delay is 0, which is usually meant to be run as soon as possible.
+ // Note: Even if the thread is scheduled to wake up now/soon, on some
+ // systems there could be a significant delay compared to notifying, which
+ // is almost immediate; and some users of 0-delay depend on it being this
+ // fast!
+ const TimeDuration minTimerDelay = TimeDuration::FromMilliseconds(
+ StaticPrefs::timer_minimum_firing_delay_tolerance_ms());
+ const TimeDuration maxTimerDelay = TimeDuration::FromMilliseconds(
+ StaticPrefs::timer_maximum_firing_delay_tolerance_ms());
+ const TimeDuration firingDelay = ComputeAcceptableFiringDelay(
+ aTimer->mDelay, minTimerDelay, maxTimerDelay);
+ const bool firingBeforeNextWakeup =
+ mIntendedWakeupTime.IsNull() ||
+ (aTimer->mTimeout + firingDelay < mIntendedWakeupTime);
+ const bool wakeUpTimerThread =
+ mWaiting && (firingBeforeNextWakeup || aTimer->mDelay.IsZero());
+
+#if TIMER_THREAD_STATISTICS
+ if (mTotalTimersAdded == 0) {
+ mFirstTimerAdded = TimeStamp::Now();
+ }
+ ++mTotalTimersAdded;
+#endif
+
+ // Add the timer to our list.
+ if (!AddTimerInternal(*aTimer)) {
+ return NS_ERROR_OUT_OF_MEMORY;
+ }
+
+ if (wakeUpTimerThread) {
+ mNotified = true;
+ mMonitor.Notify();
+ }
+
+ if (profiler_thread_is_being_profiled_for_markers(mProfilerThreadId)) {
+ nsAutoCString name;
+ aTimer->GetName(name, aProofOfLock);
+
+ nsLiteralCString prefix("Anonymous_");
+ profiler_add_marker(
+ "AddTimer", geckoprofiler::category::OTHER,
+ MarkerOptions(MarkerThreadId(mProfilerThreadId),
+ MarkerStack::MaybeCapture(
+ name.Equals("nonfunction:JS") ||
+ StringHead(name, prefix.Length()) == prefix)),
+ AddRemoveTimerMarker{}, name, aTimer->mDelay.ToMilliseconds(),
+ MarkerThreadId::CurrentThread());
+ }
+
+ return NS_OK;
+}
+
+nsresult TimerThread::RemoveTimer(nsTimerImpl* aTimer,
+ const MutexAutoLock& aProofOfLock) {
+ MonitorAutoLock lock(mMonitor);
+ AUTO_TIMERS_STATS(TimerThread_RemoveTimer);
+
+ // Remove the timer from our array. Tell callers that aTimer was not found
+ // by returning NS_ERROR_NOT_AVAILABLE.
+
+ if (!RemoveTimerInternal(*aTimer)) {
+ return NS_ERROR_NOT_AVAILABLE;
+ }
+
+#if TIMER_THREAD_STATISTICS
+ ++mTotalTimersRemoved;
+#endif
+
+ // Note: The timer thread is *not* awoken.
+ // The removed-timer entry is just left null, and will be reused (by a new or
+ // re-set timer) or discarded (when the timer thread logic handles non-null
+ // timers around it).
+ // If this was the front timer, and in the unlikely case that its entry is not
+ // soon reused by a re-set timer, the timer thread will wake up at the
+ // previously-scheduled time, but will quickly notice that there is no actual
+ // pending timer, and will restart its wait until the following real timeout.
+
+ if (profiler_thread_is_being_profiled_for_markers(mProfilerThreadId)) {
+ nsAutoCString name;
+ aTimer->GetName(name, aProofOfLock);
+
+ nsLiteralCString prefix("Anonymous_");
+ // This marker is meant to help understand the behavior of the timer thread.
+ profiler_add_marker(
+ "RemoveTimer", geckoprofiler::category::OTHER,
+ MarkerOptions(MarkerThreadId(mProfilerThreadId),
+ MarkerStack::MaybeCapture(
+ name.Equals("nonfunction:JS") ||
+ StringHead(name, prefix.Length()) == prefix)),
+ AddRemoveTimerMarker{}, name, aTimer->mDelay.ToMilliseconds(),
+ MarkerThreadId::CurrentThread());
+ // This adds a marker with the timer name as the marker name, to make it
+ // obvious which timers are being used. This marker will be useful to
+ // understand which timers might be added and removed excessively often.
+ profiler_add_marker(name, geckoprofiler::category::TIMER,
+ MarkerOptions(MarkerTiming::IntervalUntilNowFrom(
+ aTimer->mTimeout - aTimer->mDelay),
+ MarkerThreadId(mProfilerThreadId)),
+ TimerMarker{}, aTimer->mDelay.ToMilliseconds(),
+ aTimer->mType, MarkerThreadId::CurrentThread(), true);
+ }
+
+ return NS_OK;
+}
+
+TimeStamp TimerThread::FindNextFireTimeForCurrentThread(TimeStamp aDefault,
+ uint32_t aSearchBound) {
+ MonitorAutoLock lock(mMonitor);
+ AUTO_TIMERS_STATS(TimerThread_FindNextFireTimeForCurrentThread);
+
+ for (const Entry& entry : mTimers) {
+ const nsTimerImpl* timer = entry.Value();
+ if (timer) {
+ if (entry.Timeout() > aDefault) {
+ return aDefault;
+ }
+
+ // Don't yield to timers created with the *_LOW_PRIORITY type.
+ if (!timer->IsLowPriority()) {
+ bool isOnCurrentThread = false;
+ nsresult rv =
+ timer->mEventTarget->IsOnCurrentThread(&isOnCurrentThread);
+ if (NS_SUCCEEDED(rv) && isOnCurrentThread) {
+ return entry.Timeout();
+ }
+ }
+
+ if (aSearchBound == 0) {
+ // Couldn't find any non-low priority timers for the current thread.
+ // Return a compromise between a very short and a long idle time.
+ TimeStamp fallbackDeadline =
+ TimeStamp::Now() + TimeDuration::FromMilliseconds(16);
+ return fallbackDeadline < aDefault ? fallbackDeadline : aDefault;
+ }
+
+ --aSearchBound;
+ }
+ }
+
+ // No timers for this thread, return the default.
+ return aDefault;
+}
+
+// This function must be called from within a lock
+// Also: we hold the mutex for the nsTimerImpl.
+bool TimerThread::AddTimerInternal(nsTimerImpl& aTimer) {
+ mMonitor.AssertCurrentThreadOwns();
+ aTimer.mMutex.AssertCurrentThreadOwns();
+ AUTO_TIMERS_STATS(TimerThread_AddTimerInternal);
+ if (mShutdown) {
+ return false;
+ }
+
+ LogTimerEvent::LogDispatch(&aTimer);
+
+ const TimeStamp& timeout = aTimer.mTimeout;
+ const size_t insertionIndex = ComputeTimerInsertionIndex(timeout);
+
+ if (insertionIndex != 0 && !mTimers[insertionIndex - 1].Value()) {
+ // Very common scenario in practice: The timer just before the insertion
+ // point is canceled, overwrite it.
+ AUTO_TIMERS_STATS(TimerThread_AddTimerInternal_overwrite_before);
+ mTimers[insertionIndex - 1] = Entry{aTimer};
+ return true;
+ }
+
+ const size_t length = mTimers.Length();
+ if (insertionIndex == length) {
+ // We're at the end (including it's the very first insertion), add new timer
+ // at the end.
+ AUTO_TIMERS_STATS(TimerThread_AddTimerInternal_append);
+ return mTimers.AppendElement(Entry{aTimer}, mozilla::fallible);
+ }
+
+ if (!mTimers[insertionIndex].Value()) {
+ // The timer at the insertion point is canceled, overwrite it.
+ AUTO_TIMERS_STATS(TimerThread_AddTimerInternal_overwrite);
+ mTimers[insertionIndex] = Entry{aTimer};
+ return true;
+ }
+
+ // The new timer has to be inserted.
+ AUTO_TIMERS_STATS(TimerThread_AddTimerInternal_insert);
+ // The capacity should be checked first, because if it needs to be increased
+ // and the memory allocation fails, only the new timer should be lost.
+ if (length == mTimers.Capacity() && mTimers[length - 1].Value()) {
+ // We have reached capacity, and the last entry is not canceled, so we
+ // really want to increase the capacity in case the extra slot is required.
+ // To force-expand the array, append a canceled-timer entry with a timestamp
+ // far in the future.
+ // This empty Entry may be used below to receive the moved-from previous
+ // entry. If not, it may be used in a later call if we need to append a new
+ // timer at the end.
+ AUTO_TIMERS_STATS(TimerThread_AddTimerInternal_insert_expand);
+ if (!mTimers.AppendElement(
+ Entry{mTimers[length - 1].Timeout() +
+ TimeDuration::FromSeconds(365.0 * 24.0 * 60.0 * 60.0)},
+ mozilla::fallible)) {
+ return false;
+ }
+ }
+
+ // Extract the timer at the insertion point, and put the new timer in its
+ // place.
+ Entry extractedEntry = std::exchange(mTimers[insertionIndex], Entry{aTimer});
+ // Following entries can be pushed until we hit a canceled timer or the end.
+ for (size_t i = insertionIndex + 1; i < length; ++i) {
+ Entry& entryRef = mTimers[i];
+ if (!entryRef.Value()) {
+ // Canceled entry, overwrite it with the extracted entry from before.
+ COUNT_TIMERS_STATS(TimerThread_AddTimerInternal_insert_overwrite);
+ entryRef = std::move(extractedEntry);
+ return true;
+ }
+ // Write extracted entry from before, and extract current entry.
+ COUNT_TIMERS_STATS(TimerThread_AddTimerInternal_insert_shifts);
+ std::swap(entryRef, extractedEntry);
+ }
+ // We've reached the end of the list, with still one extracted entry to
+ // re-insert. We've checked the capacity above, this cannot fail.
+ COUNT_TIMERS_STATS(TimerThread_AddTimerInternal_insert_append);
+ mTimers.AppendElement(std::move(extractedEntry));
+ return true;
+}
+
+// This function must be called from within a lock
+// Also: we hold the mutex for the nsTimerImpl.
+bool TimerThread::RemoveTimerInternal(nsTimerImpl& aTimer) {
+ mMonitor.AssertCurrentThreadOwns();
+ aTimer.mMutex.AssertCurrentThreadOwns();
+ AUTO_TIMERS_STATS(TimerThread_RemoveTimerInternal);
+ if (!aTimer.IsInTimerThread()) {
+ COUNT_TIMERS_STATS(TimerThread_RemoveTimerInternal_not_in_list);
+ return false;
+ }
+ AUTO_TIMERS_STATS(TimerThread_RemoveTimerInternal_in_list);
+ for (auto& entry : mTimers) {
+ if (entry.Value() == &aTimer) {
+ entry.Forget();
+ return true;
+ }
+ }
+ MOZ_ASSERT(!aTimer.IsInTimerThread(),
+ "Not found in the list but it should be!?");
+ return false;
+}
+
+void TimerThread::RemoveLeadingCanceledTimersInternal() {
+ mMonitor.AssertCurrentThreadOwns();
+ AUTO_TIMERS_STATS(TimerThread_RemoveLeadingCanceledTimersInternal);
+
+ size_t toRemove = 0;
+ while (toRemove < mTimers.Length() && !mTimers[toRemove].Value()) {
+ ++toRemove;
+ }
+ mTimers.RemoveElementsAt(0, toRemove);
+}
+
+void TimerThread::RemoveFirstTimerInternal() {
+ mMonitor.AssertCurrentThreadOwns();
+ AUTO_TIMERS_STATS(TimerThread_RemoveFirstTimerInternal);
+ MOZ_ASSERT(!mTimers.IsEmpty());
+ mTimers.RemoveElementAt(0);
+}
+
+void TimerThread::PostTimerEvent(already_AddRefed<nsTimerImpl> aTimerRef) {
+ mMonitor.AssertCurrentThreadOwns();
+ AUTO_TIMERS_STATS(TimerThread_PostTimerEvent);
+
+ RefPtr<nsTimerImpl> timer(aTimerRef);
+
+#if TIMER_THREAD_STATISTICS
+ const double actualFiringDelay =
+ std::max((TimeStamp::Now() - timer->mTimeout).ToMilliseconds(), 0.0);
+ if (mNotified) {
+ ++mTotalTimersFiredNotified;
+ mTotalActualTimerFiringDelayNotified += actualFiringDelay;
+ } else {
+ ++mTotalTimersFiredUnnotified;
+ mTotalActualTimerFiringDelayUnnotified += actualFiringDelay;
+ }
+#endif
+
+ if (!timer->mEventTarget) {
+ NS_ERROR("Attempt to post timer event to NULL event target");
+ return;
+ }
+
+ // XXX we may want to reuse this nsTimerEvent in the case of repeating timers.
+
+ // Since we already addref'd 'timer', 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.
+
+ nsCOMPtr<nsIEventTarget> target = timer->mEventTarget;
+
+ void* p = nsTimerEvent::operator new(sizeof(nsTimerEvent));
+ if (!p) {
+ return;
+ }
+ RefPtr<nsTimerEvent> event =
+ ::new (KnownNotNull, p) nsTimerEvent(timer.forget(), mProfilerThreadId);
+
+ nsresult rv;
+ {
+ // We release mMonitor around the Dispatch because if the Dispatch interacts
+ // with the timer API we'll deadlock.
+ MonitorAutoUnlock unlock(mMonitor);
+ rv = target->Dispatch(event, NS_DISPATCH_NORMAL);
+ if (NS_FAILED(rv)) {
+ timer = event->ForgetTimer();
+ // We do this to avoid possible deadlock by taking the two locks in a
+ // different order than is used in RemoveTimer(). RemoveTimer() has
+ // aTimer->mMutex first. We use timer.get() to keep static analysis
+ // happy
+ // NOTE: I'm not sure that any of the below is actually necessary. It
+ // seems to me that the timer that we're trying to fire will have already
+ // been removed prior to this.
+ MutexAutoLock lock1(timer.get()->mMutex);
+ MonitorAutoLock lock2(mMonitor);
+ RemoveTimerInternal(*timer);
+ }
+ }
+}
+
+void TimerThread::DoBeforeSleep() {
+ // Mainthread
+ MonitorAutoLock lock(mMonitor);
+ mSleeping = true;
+}
+
+// Note: wake may be notified without preceding sleep notification
+void TimerThread::DoAfterSleep() {
+ // Mainthread
+ MonitorAutoLock lock(mMonitor);
+ mSleeping = false;
+
+ // Wake up the timer thread to re-process the array to ensure the sleep delay
+ // is correct, and fire any expired timers (perhaps quite a few)
+ mNotified = true;
+ PROFILER_MARKER_UNTYPED("AfterSleep", OTHER,
+ MarkerThreadId(mProfilerThreadId));
+ mMonitor.Notify();
+}
+
+NS_IMETHODIMP
+TimerThread::Observe(nsISupports* aSubject, const char* aTopic,
+ const char16_t* aData) {
+ if (strcmp(aTopic, "ipc:process-priority-changed") == 0) {
+ nsCOMPtr<nsIPropertyBag2> props = do_QueryInterface(aSubject);
+ MOZ_ASSERT(props != nullptr);
+
+ int32_t priority = static_cast<int32_t>(hal::PROCESS_PRIORITY_UNKNOWN);
+ props->GetPropertyAsInt32(u"priority"_ns, &priority);
+ mCachedPriority.store(static_cast<hal::ProcessPriority>(priority),
+ std::memory_order_relaxed);
+ }
+
+ if (StaticPrefs::timer_ignore_sleep_wake_notifications()) {
+ return NS_OK;
+ }
+
+ if (strcmp(aTopic, "sleep_notification") == 0 ||
+ strcmp(aTopic, "suspend_process_notification") == 0) {
+ DoBeforeSleep();
+ } else if (strcmp(aTopic, "wake_notification") == 0 ||
+ strcmp(aTopic, "resume_process_notification") == 0) {
+ DoAfterSleep();
+ }
+
+ return NS_OK;
+}
+
+uint32_t TimerThread::AllowedEarlyFiringMicroseconds() {
+ MonitorAutoLock lock(mMonitor);
+ return mAllowedEarlyFiringMicroseconds;
+}
+
+#if TIMER_THREAD_STATISTICS
+void TimerThread::PrintStatistics() const {
+ mMonitor.AssertCurrentThreadOwns();
+
+ const TimeStamp freshNow = TimeStamp::Now();
+ const double timeElapsed = mFirstTimerAdded.IsNull()
+ ? 0.0
+ : (freshNow - mFirstTimerAdded).ToSeconds();
+ printf_stderr("TimerThread Stats (Total time %8.2fs)\n", timeElapsed);
+
+ printf_stderr("Added: %6llu Removed: %6llu Fired: %6llu\n", mTotalTimersAdded,
+ mTotalTimersRemoved,
+ mTotalTimersFiredNotified + mTotalTimersFiredUnnotified);
+
+ auto PrintTimersFiredBucket =
+ [](const AutoTArray<size_t, sTimersFiredPerWakeupBucketCount>& buckets,
+ const size_t wakeupCount, const size_t timersFiredCount,
+ const double totalTimerDelay, const char* label) {
+ printf_stderr("%s : [", label);
+ for (size_t bucketVal : buckets) {
+ printf_stderr(" %5llu", bucketVal);
+ }
+ printf_stderr(
+ " ] Wake-ups/timer %6llu / %6llu (%7.4f) Avg Timer Delay %7.4f\n",
+ wakeupCount, timersFiredCount,
+ static_cast<double>(wakeupCount) / timersFiredCount,
+ totalTimerDelay / timersFiredCount);
+ };
+
+ printf_stderr("Wake-ups:\n");
+ PrintTimersFiredBucket(
+ mTimersFiredPerWakeup, mTotalWakeupCount,
+ mTotalTimersFiredNotified + mTotalTimersFiredUnnotified,
+ mTotalActualTimerFiringDelayNotified +
+ mTotalActualTimerFiringDelayUnnotified,
+ "Total ");
+ PrintTimersFiredBucket(mTimersFiredPerNotifiedWakeup,
+ mTotalNotifiedWakeupCount, mTotalTimersFiredNotified,
+ mTotalActualTimerFiringDelayNotified, "Notified ");
+ PrintTimersFiredBucket(mTimersFiredPerUnnotifiedWakeup,
+ mTotalUnnotifiedWakeupCount,
+ mTotalTimersFiredUnnotified,
+ mTotalActualTimerFiringDelayUnnotified, "Unnotified ");
+
+ printf_stderr("Early Wake-ups: %6llu Avg: %7.4fms\n", mEarlyWakeups,
+ mTotalEarlyWakeupTime / mEarlyWakeups);
+}
+#endif
+
+/* This nsReadOnlyTimer class is used for the values returned by the
+ * TimerThread::GetTimers method.
+ * It is not possible to return a strong reference to the nsTimerImpl
+ * instance (that could extend the lifetime of the timer and cause it to fire
+ * a callback pointing to already freed memory) or a weak reference
+ * (nsSupportsWeakReference doesn't support freeing the referee on a thread
+ * that isn't the thread that owns the weak reference), so instead the timer
+ * name, delay and type are copied to a new object. */
+class nsReadOnlyTimer final : public nsITimer {
+ public:
+ explicit nsReadOnlyTimer(const nsACString& aName, uint32_t aDelay,
+ uint32_t aType)
+ : mName(aName), mDelay(aDelay), mType(aType) {}
+ NS_DECL_ISUPPORTS
+
+ NS_IMETHOD Init(nsIObserver* aObserver, uint32_t aDelayInMs,
+ uint32_t aType) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ NS_IMETHOD InitWithCallback(nsITimerCallback* aCallback, uint32_t aDelayInMs,
+ uint32_t aType) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ NS_IMETHOD InitHighResolutionWithCallback(nsITimerCallback* aCallback,
+ const mozilla::TimeDuration& aDelay,
+ uint32_t aType) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ NS_IMETHOD Cancel(void) override { return NS_ERROR_NOT_IMPLEMENTED; }
+ NS_IMETHOD InitWithNamedFuncCallback(nsTimerCallbackFunc aCallback,
+ void* aClosure, uint32_t aDelay,
+ uint32_t aType,
+ const char* aName) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ NS_IMETHOD InitHighResolutionWithNamedFuncCallback(
+ nsTimerCallbackFunc aCallback, void* aClosure,
+ const mozilla::TimeDuration& aDelay, uint32_t aType,
+ const char* aName) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+
+ NS_IMETHOD GetName(nsACString& aName) override {
+ aName = mName;
+ return NS_OK;
+ }
+ NS_IMETHOD GetDelay(uint32_t* aDelay) override {
+ *aDelay = mDelay;
+ return NS_OK;
+ }
+ NS_IMETHOD SetDelay(uint32_t aDelay) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ NS_IMETHOD GetType(uint32_t* aType) override {
+ *aType = mType;
+ return NS_OK;
+ }
+ NS_IMETHOD SetType(uint32_t aType) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ NS_IMETHOD GetClosure(void** aClosure) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ NS_IMETHOD GetCallback(nsITimerCallback** aCallback) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ NS_IMETHOD GetTarget(nsIEventTarget** aTarget) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ NS_IMETHOD SetTarget(nsIEventTarget* aTarget) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ NS_IMETHOD GetAllowedEarlyFiringMicroseconds(
+ uint32_t* aAllowedEarlyFiringMicroseconds) override {
+ return NS_ERROR_NOT_IMPLEMENTED;
+ }
+ size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) override {
+ return sizeof(*this);
+ }
+
+ private:
+ nsCString mName;
+ uint32_t mDelay;
+ uint32_t mType;
+ ~nsReadOnlyTimer() = default;
+};
+
+NS_IMPL_ISUPPORTS(nsReadOnlyTimer, nsITimer)
+
+nsresult TimerThread::GetTimers(nsTArray<RefPtr<nsITimer>>& aRetVal) {
+ nsTArray<RefPtr<nsTimerImpl>> timers;
+ {
+ MonitorAutoLock lock(mMonitor);
+ for (const auto& entry : mTimers) {
+ nsTimerImpl* timer = entry.Value();
+ if (!timer) {
+ continue;
+ }
+ timers.AppendElement(timer);
+ }
+ }
+
+ for (nsTimerImpl* timer : timers) {
+ nsAutoCString name;
+ timer->GetName(name);
+
+ uint32_t delay;
+ timer->GetDelay(&delay);
+
+ uint32_t type;
+ timer->GetType(&type);
+
+ aRetVal.AppendElement(new nsReadOnlyTimer(name, delay, type));
+ }
+
+ return NS_OK;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-28 05:20:38 +0000