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[Win] Improvements to run loop timer resolution #42936

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Merged
merged 1 commit into from
Mar 28, 2025
Merged

[Win] Improvements to run loop timer resolution #42936

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4 changes: 3 additions & 1 deletion Source/WTF/wtf/RunLoop.h
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Original file line number Diff line number Diff line change
Expand Up @@ -263,8 +263,10 @@ class WTF_CAPABILITY("is current") RunLoop final : public GuaranteedSerialFuncti
#if USE(WINDOWS_EVENT_LOOP)
static LRESULT CALLBACK RunLoopWndProc(HWND, UINT, WPARAM, LPARAM);
LRESULT wndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
DWORD msTillNextTimer();
void fireTimers();
HWND m_runLoopMessageWindow;
UncheckedKeyHashSet<UINT_PTR> m_liveTimers;
Deque<TimerBase*> m_timers;

Lock m_loopLock;
#elif USE(COCOA_EVENT_LOOP)
Expand Down
100 changes: 77 additions & 23 deletions Source/WTF/wtf/win/RunLoopWin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ namespace WTF {

static const UINT PerformWorkMessage = WM_USER + 1;
static const UINT SetTimerMessage = WM_USER + 2;
static const UINT KillTimerMessage = WM_USER + 3;
static const UINT FireTimerMessage = WM_USER + 3;
static const LPCWSTR kRunLoopMessageWindowClassName = L"RunLoopMessageWindow";

LRESULT CALLBACK RunLoop::RunLoopWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
Expand All @@ -58,18 +58,10 @@ LRESULT RunLoop::wndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
performWork();
return 0;
case SetTimerMessage:
::SetTimer(hWnd, wParam, lParam, nullptr);
return 0;
case KillTimerMessage:
::KillTimer(hWnd, wParam);
return 0;
case WM_TIMER:
case FireTimerMessage:
RunLoop::TimerBase* timer = nullptr;
{
Locker locker { m_loopLock };
if (m_liveTimers.contains(wParam))
timer = std::bit_cast<RunLoop::TimerBase*>(wParam);
}
timer = std::bit_cast<RunLoop::TimerBase*>(wParam);
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@fujii fujii Mar 29, 2025

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timer can be already destroyed here. I fixed it in #43244

if (timer != nullptr)
timer->timerFired();
return 0;
Expand All @@ -80,12 +72,55 @@ LRESULT RunLoop::wndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)

void RunLoop::run()
{
MSG message;
while (BOOL result = ::GetMessage(&message, nullptr, 0, 0)) {
if (result == -1)
break;
::TranslateMessage(&message);
::DispatchMessage(&message);
while (true) {
RunLoop::currentSingleton().fireTimers();
MSG message;
while (BOOL result = ::PeekMessage(&message, nullptr, 0, 0, PM_REMOVE)) {
if (result == -1)
break;
if (message.message == WM_QUIT)
return;
::TranslateMessage(&message);
::DispatchMessage(&message);
}

DWORD timeout = RunLoop::currentSingleton().msTillNextTimer();
if (timeout > 0)
::MsgWaitForMultipleObjectsEx(0, nullptr, timeout, QS_ALLINPUT, MWMO_INPUTAVAILABLE);
}
}

DWORD RunLoop::msTillNextTimer()
{
Locker locker { m_loopLock };
Seconds timeout = Seconds(3600);

if (!m_timers.isEmpty()) {
auto now = MonotonicTime::now();
auto firstTimer = m_timers.last();

timeout = std::max<Seconds>(firstTimer->m_nextFireDate - now, 0_s);
}
return timeout.milliseconds();
}

void RunLoop::fireTimers()
{
Locker locker { m_loopLock };

// Can bail here if there's no timers before we check the time
if (m_timers.isEmpty())
return;

// Fire any timers ready from the front of the queue
auto now = MonotonicTime::now();

while (!m_timers.isEmpty()) {
auto timer = m_timers.last();
if (timer->m_nextFireDate > now)
return;
::PostMessage(m_runLoopMessageWindow, FireTimerMessage, std::bit_cast<uintptr_t>(timer), 0LL);
m_timers.removeLast();
}
}

Expand Down Expand Up @@ -137,6 +172,7 @@ void RunLoop::wakeUp()

RunLoop::CycleResult RunLoop::cycle(RunLoopMode)
{
RunLoop::currentSingleton().fireTimers();
MSG message;
while (::PeekMessage(&message, nullptr, 0, 0, PM_REMOVE)) {
if (message.message == WM_QUIT)
Expand All @@ -160,9 +196,13 @@ void RunLoop::TimerBase::timerFired()

if (!m_isRepeating) {
m_isActive = false;
::KillTimer(m_runLoop->m_runLoopMessageWindow, std::bit_cast<uintptr_t>(this));
} else
m_nextFireDate = MonotonicTime::infinity();
} else {
m_nextFireDate = MonotonicTime::timePointFromNow(m_interval);
m_runLoop->m_timers.appendAndBubble(this, [&] (TimerBase* otherTimer) -> bool {
return m_nextFireDate > otherTimer->m_nextFireDate;
});
}
}

fired();
Expand All @@ -181,12 +221,23 @@ RunLoop::TimerBase::~TimerBase()
void RunLoop::TimerBase::start(Seconds interval, bool repeat)
{
Locker locker { m_runLoop->m_loopLock };
if (isActiveWithLock()) {
// Rescheduling timer that's already started
m_runLoop->m_timers.removeFirstMatching([&] (TimerBase* t) -> bool {
return this == t;
});
}

m_isRepeating = repeat;
m_isActive = true;
m_interval = interval;
m_nextFireDate = MonotonicTime::timePointFromNow(m_interval);
m_runLoop->m_liveTimers.add(std::bit_cast<uintptr_t>(this));
::PostMessage(m_runLoop->m_runLoopMessageWindow, SetTimerMessage, std::bit_cast<uintptr_t>(this), interval.millisecondsAs<UINT>());
m_runLoop->m_timers.appendAndBubble(this, [&] (TimerBase* otherTimer) -> bool {
return m_nextFireDate > otherTimer->m_nextFireDate;
});
// If this is the first timer now, we need to cycle the run loop so we don't sleep through it
if (m_runLoop->m_timers.last() == this)
::PostMessage(m_runLoop->m_runLoopMessageWindow, SetTimerMessage, std::bit_cast<uintptr_t>(this), interval.millisecondsAs<UINT>());
}

void RunLoop::TimerBase::stop()
Expand All @@ -196,8 +247,11 @@ void RunLoop::TimerBase::stop()
return;

m_isActive = false;
m_runLoop->m_liveTimers.remove(std::bit_cast<uintptr_t>(this));
::PostMessage(m_runLoop->m_runLoopMessageWindow, KillTimerMessage, std::bit_cast<uintptr_t>(this), 0LL);
m_nextFireDate = MonotonicTime::infinity();

m_runLoop->m_timers.removeFirstMatching([&] (TimerBase* t) -> bool {
return this == t;
});
}

bool RunLoop::TimerBase::isActiveWithLock() const
Expand Down