tracePoint(ScheduleRenderingUpdate) should not be invoked if there is…

… a scheduled rendering update already

https://bugs.webkit.org/show_bug.cgi?id=258849
rdar://110032497

Reviewed by Simon Fraser.

Firing tracepoints is not free, especially on non-production kernels.

* Source/WebCore/page/RenderingUpdateScheduler.cpp:
(WebCore::RenderingUpdateScheduler::adjustRenderingUpdateFrequency):
(WebCore::RenderingUpdateScheduler::isScheduled const):

Make isScheduled() work in all cases, not just for the timer fallback.
This way we bail out early if there a scheduled update already.

(WebCore::RenderingUpdateScheduler::startTimer):

Get rid of the unneeded and confusing m_scheduled bit.

(WebCore::RenderingUpdateScheduler::clearScheduled):
* Source/WebCore/page/RenderingUpdateScheduler.h:

Canonical link: https://commits.webkit.org/265761@main

Source/WebCore/page/RenderingUpdateScheduler.cpp

@@ -59,7 +59,7 @@ void RenderingUpdateScheduler::adjustRenderingUpdateFrequency()
     } else
         m_useTimer = true;
 
-    if (isScheduled()) {
+    if (m_refreshTimer) {
         clearScheduled();
         scheduleRenderingUpdate();
     }
@@ -90,23 +90,20 @@ void RenderingUpdateScheduler::scheduleRenderingUpdate()
 
 bool RenderingUpdateScheduler::isScheduled() const
 {
-    ASSERT_IMPLIES(m_refreshTimer.get(), m_scheduled);
-    return m_scheduled;
+    return m_refreshTimer || DisplayRefreshMonitorClient::isScheduled();
 }
 
 void RenderingUpdateScheduler::startTimer(Seconds delay)
 {
     LOG_WITH_STREAM(EventLoop, stream << "RenderingUpdateScheduler for page " << &m_page << " startTimer(" << delay << ")");
 
-    ASSERT(!isScheduled());
+    ASSERT(!m_refreshTimer);
     m_refreshTimer = makeUnique<Timer>(*this, &RenderingUpdateScheduler::displayRefreshFired);
     m_refreshTimer->startOneShot(delay);
-    m_scheduled = true;
 }
 
 void RenderingUpdateScheduler::clearScheduled()
 {
-    m_scheduled = false;
     m_refreshTimer = nullptr;
 }
 

Source/WebCore/page/RenderingUpdateScheduler.h

@@ -65,7 +65,6 @@ class RenderingUpdateScheduler final : public DisplayRefreshMonitorClient {
     std::unique_ptr<Timer> m_refreshTimer;
     unsigned m_rescheduledRenderingUpdateCount { 0 };
     bool m_useTimer { false };
-    bool m_scheduled { false };
 };
 
 }