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gecko-dev/xpcom/threads/TimerThread.cpp

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/* -*- 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;
}
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