Bug 1696527 - Remove unused 'JankLevel' code from nsRefreshDriver, r=bas

Differential Revision: https://phabricator.services.mozilla.com/D107283

layout/base/nsRefreshDriver.cpp

@@ -129,24 +129,6 @@ static mozilla::LazyLogModule sRefreshDriverLog("nsRefreshDriver");
 MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(nsRefreshDriver::TickReasons);
 
 namespace {
-// `true` if we are currently in jank-critical mode.
-//
-// In jank-critical mode, any iteration of the event loop that takes
-// more than 16ms to compute will cause an ongoing animation to miss
-// frames.
-//
-// For simplicity, the current implementation assumes that we are in
-// jank-critical mode if and only if at least one vsync driver has
-// at least one observer.
-static uint64_t sActiveVsyncTimers = 0;
-
-// The latest value of process-wide jank levels.
-//
-// For each i, sJankLevels[i] counts the number of times delivery of
-// vsync to the main thread has been delayed by at least 2^i ms. Use
-// GetJankLevels to grab a copy of this array.
-uint64_t sJankLevels[12];
-
 // The number outstanding nsRefreshDrivers (that have been created but not
 // disconnected). When this reaches zero we will call
 // nsRefreshDriver::Shutdown.
@@ -654,7 +636,6 @@ class VsyncRefreshDriverTimer : public RefreshDriverTimer {
             Telemetry::FX_REFRESH_DRIVER_CHROME_FRAME_DELAY_MS, sample);
         Telemetry::Accumulate(
             Telemetry::FX_REFRESH_DRIVER_SYNC_SCROLL_FRAME_DELAY_MS, sample);
-        RecordJank(sample);
       } else if (mVsyncRate != TimeDuration::Forever()) {
         TimeDuration contentDelay = (TimeStamp::Now() - mLastTick) - mVsyncRate;
         if (contentDelay.ToMilliseconds() < 0) {
@@ -668,7 +649,6 @@ class VsyncRefreshDriverTimer : public RefreshDriverTimer {
             Telemetry::FX_REFRESH_DRIVER_CONTENT_FRAME_DELAY_MS, sample);
         Telemetry::Accumulate(
             Telemetry::FX_REFRESH_DRIVER_SYNC_SCROLL_FRAME_DELAY_MS, sample);
-        RecordJank(sample);
       } else {
         // Request the vsync rate from the parent process. Might be a few vsyncs
         // until the parent responds.
@@ -679,15 +659,6 @@ class VsyncRefreshDriverTimer : public RefreshDriverTimer {
 #endif
     }
 
-    void RecordJank(uint32_t aJankMS) {
-      uint32_t duration = 1 /* ms */;
-      for (size_t i = 0;
-           i < mozilla::ArrayLength(sJankLevels) && duration < aJankMS;
-           ++i, duration *= 2) {
-        sJankLevels[i]++;
-      }
-    }
-
     void TickRefreshDriver(VsyncId aId, TimeStamp aVsyncTimestamp) {
       MOZ_ASSERT(NS_IsMainThread());
 
@@ -761,7 +732,6 @@ class VsyncRefreshDriverTimer : public RefreshDriverTimer {
   }
 
   void StartTimer() override {
-    // Protect updates to `sActiveVsyncTimers`.
     MOZ_ASSERT(NS_IsMainThread());
 
     mLastFireTime = TimeStamp::Now();
@@ -772,12 +742,9 @@ class VsyncRefreshDriverTimer : public RefreshDriverTimer {
       mVsyncChild->AddChildRefreshTimer(mVsyncObserver);
       mVsyncObserver->OnTimerStart();
     }
-
-    ++sActiveVsyncTimers;
   }
 
   void StopTimer() override {
-    // Protect updates to `sActiveVsyncTimers`.
     MOZ_ASSERT(NS_IsMainThread());
 
     if (mVsyncDispatcher) {
@@ -785,9 +752,6 @@ class VsyncRefreshDriverTimer : public RefreshDriverTimer {
     } else if (mVsyncChild) {
       mVsyncChild->RemoveChildRefreshTimer(mVsyncObserver);
     }
-
-    MOZ_ASSERT(sActiveVsyncTimers > 0);
-    --sActiveVsyncTimers;
   }
 
   void ScheduleNextTick(TimeStamp aNowTime) override {
@@ -982,8 +946,6 @@ static StaticRefPtr<InactiveRefreshDriverTimer> sThrottledRateTimer;
 void nsRefreshDriver::CreateVsyncRefreshTimer() {
   MOZ_ASSERT(NS_IsMainThread());
 
-  PodArrayZero(sJankLevels);
-
   if (gfxPlatform::IsInLayoutAsapMode()) {
     return;
   }
@@ -2794,16 +2756,4 @@ void nsRefreshDriver::Disconnect() {
   }
 }
 
-/* static */
-bool nsRefreshDriver::IsJankCritical() {
-  MOZ_ASSERT(NS_IsMainThread());
-  return sActiveVsyncTimers > 0;
-}
-
-/* static */
-bool nsRefreshDriver::GetJankLevels(Vector<uint64_t>& aJank) {
-  aJank.clear();
-  return aJank.append(sJankLevels, ArrayLength(sJankLevels));
-}
-
 #undef LOG

layout/base/nsRefreshDriver.h

@@ -321,20 +321,6 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
   void SetIsResizeSuppressed() { mResizeSuppressed = true; }
   bool IsResizeSuppressed() const { return mResizeSuppressed; }
 
-  /**
-   * The latest value of process-wide jank levels.
-   *
-   * For each i, sJankLevels[i] counts the number of times delivery of
-   * vsync to the main thread has been delayed by at least 2^i
-   * ms. This data structure has been designed to make it easy to
-   * determine how much jank has taken place between two instants in
-   * time.
-   *
-   * Return `false` if `aJank` needs to be grown to accomodate the
-   * data but we didn't have enough memory.
-   */
-  static bool GetJankLevels(mozilla::Vector<uint64_t>& aJank);
-
   // mozilla::layers::TransactionIdAllocator
   TransactionId GetTransactionId(bool aThrottle) override;
   TransactionId LastTransactionId() const override;
@@ -617,17 +603,6 @@ class nsRefreshDriver final : public mozilla::layers::TransactionIdAllocator,
   friend class mozilla::RefreshDriverTimer;
 
   static void Shutdown();
-
-  // `true` if we are currently in jank-critical mode.
-  //
-  // In jank-critical mode, any iteration of the event loop that takes
-  // more than 16ms to compute will cause an ongoing animation to miss
-  // frames.
-  //
-  // For simplicity, the current implementation assumes that we are
-  // in jank-critical mode if and only if the vsync driver has at least
-  // one observer.
-  static bool IsJankCritical();
 };
 
 #endif /* !defined(nsRefreshDriver_h_) */