Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 541 insertions, 0 deletions

diff --git a/dom/base/CCGCScheduler.h b/dom/base/CCGCScheduler.h
new file mode 100644
index 0000000000..87b7f16f10
--- /dev/null
+++ b/dom/base/CCGCScheduler.h
@@ -0,0 +1,541 @@
+/* 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 "js/SliceBudget.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/IdleTaskRunner.h"
+#include "mozilla/MainThreadIdlePeriod.h"
+#include "mozilla/Telemetry.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/ipc/IdleSchedulerChild.h"
+#include "nsCycleCollector.h"
+#include "nsJSEnvironment.h"
+#include "nsCycleCollectionParticipant.h"
+
+namespace mozilla {
+
+extern const TimeDuration kOneMinute;
+
+// The amount of time we wait between a request to CC (after GC ran)
+// and doing the actual CC.
+extern const TimeDuration kCCDelay;
+
+extern const TimeDuration kCCSkippableDelay;
+
+// In case the cycle collector isn't run at all, we don't want forget skippables
+// to run too often. So limit the forget skippable cycle to start at earliest 2
+// seconds after the end of the previous cycle.
+extern const TimeDuration kTimeBetweenForgetSkippableCycles;
+
+// ForgetSkippable is usually fast, so we can use small budgets.
+// This isn't a real budget but a hint to IdleTaskRunner whether there
+// is enough time to call ForgetSkippable.
+extern const TimeDuration kForgetSkippableSliceDuration;
+
+// Maximum amount of time that should elapse between incremental CC slices
+extern const TimeDuration kICCIntersliceDelay;
+
+// Time budget for an incremental CC slice when using timer to run it.
+extern const TimeDuration kICCSliceBudget;
+// Minimum budget for an incremental CC slice when using idle time to run it.
+extern const TimeDuration kIdleICCSliceBudget;
+
+// Maximum total duration for an ICC
+extern const TimeDuration kMaxICCDuration;
+
+// Force a CC after this long if there's more than NS_CC_FORCED_PURPLE_LIMIT
+// objects in the purple buffer.
+extern const TimeDuration kCCForced;
+constexpr uint32_t kCCForcedPurpleLimit = 10;
+
+// Don't allow an incremental GC to lock out the CC for too long.
+extern const TimeDuration kMaxCCLockedoutTime;
+
+// Trigger a CC if the purple buffer exceeds this size when we check it.
+constexpr uint32_t kCCPurpleLimit = 200;
+
+// Actions performed by the GCRunner state machine.
+enum class GCRunnerAction {
+  MinorGC,        // Run a minor GC (nursery collection)
+  WaitToMajorGC,  // We want to start a new major GC
+  StartMajorGC,   // The parent says we may begin our major GC
+  GCSlice,        // Run a single slice of a major GC
+  None
+};
+
+struct GCRunnerStep {
+  GCRunnerAction mAction;
+  JS::GCReason mReason;
+};
+
+// Actions that are output from the CCRunner state machine.
+enum class CCRunnerAction {
+  // Do nothing.
+  None,
+
+  // We crossed an eager minor GC threshold in the middle of an incremental CC,
+  // and we have some idle time.
+  MinorGC,
+
+  // Various cleanup actions.
+  ForgetSkippable,
+  CleanupContentUnbinder,
+  CleanupDeferred,
+
+  // Do the actual cycle collection (build the graph etc).
+  CycleCollect,
+
+  // All done.
+  StopRunning
+};
+
+enum CCRunnerYield { Continue, Yield };
+
+enum CCRunnerForgetSkippableRemoveChildless {
+  KeepChildless = false,
+  RemoveChildless = true
+};
+
+struct CCRunnerStep {
+  // The action the scheduler is instructing the caller to perform.
+  CCRunnerAction mAction;
+
+  // Whether to stop processing actions for this invocation of the timer
+  // callback.
+  CCRunnerYield mYield;
+
+  union ActionData {
+    // If the action is ForgetSkippable, then whether to remove childless nodes
+    // or not.
+    CCRunnerForgetSkippableRemoveChildless mRemoveChildless;
+
+    // If the action is CycleCollect, the reason for the collection.
+    CCReason mCCReason;
+
+    // If the action is MinorGC, the reason for the GC.
+    JS::GCReason mReason;
+
+    MOZ_IMPLICIT ActionData(CCRunnerForgetSkippableRemoveChildless v)
+        : mRemoveChildless(v) {}
+    MOZ_IMPLICIT ActionData(CCReason v) : mCCReason(v) {}
+    MOZ_IMPLICIT ActionData(JS::GCReason v) : mReason(v) {}
+    ActionData() = default;
+  } mParam;
+};
+
+class CCGCScheduler {
+ public:
+  CCGCScheduler()
+      : mAskParentBeforeMajorGC(XRE_IsContentProcess()),
+        mReadyForMajorGC(!mAskParentBeforeMajorGC),
+        mInterruptRequested(false) {}
+
+  static bool CCRunnerFired(TimeStamp aDeadline);
+
+  // Parameter setting
+
+  void SetActiveIntersliceGCBudget(TimeDuration aDuration) {
+    mActiveIntersliceGCBudget = aDuration;
+  }
+
+  // State retrieval
+
+  TimeDuration GetCCBlockedTime(TimeStamp aNow) const {
+    MOZ_ASSERT(mInIncrementalGC);
+    MOZ_ASSERT(!mCCBlockStart.IsNull());
+    return aNow - mCCBlockStart;
+  }
+
+  bool InIncrementalGC() const { return mInIncrementalGC; }
+
+  TimeStamp GetLastCCEndTime() const { return mLastCCEndTime; }
+
+  bool IsEarlyForgetSkippable(uint32_t aN = kMajorForgetSkippableCalls) const {
+    return mCleanupsSinceLastGC < aN;
+  }
+
+  bool NeedsFullGC() const { return mNeedsFullGC; }
+
+  // Requests
+  void PokeGC(JS::GCReason aReason, JSObject* aObj, TimeDuration aDelay = 0);
+  void PokeShrinkingGC();
+  void PokeFullGC();
+  void MaybePokeCC(TimeStamp aNow, uint32_t aSuspectedCCObjects);
+  void PokeMinorGC(JS::GCReason aReason);
+
+  void UserIsInactive();
+  void UserIsActive();
+  bool IsUserActive() const { return mUserIsActive; }
+
+  void KillShrinkingGCTimer();
+  void KillFullGCTimer();
+  void KillGCRunner();
+  void KillCCRunner();
+  void KillAllTimersAndRunners();
+
+  js::SliceBudget CreateGCSliceBudget(mozilla::TimeDuration aDuration,
+                                      bool isIdle, bool isExtended) {
+    mInterruptRequested = false;
+    auto budget = js::SliceBudget(aDuration, &mInterruptRequested);
+    budget.idle = isIdle;
+    budget.extended = isExtended;
+    return budget;
+  }
+
+  /*
+   * aDelay is the delay before the first time the idle task runner runs.
+   * Then it runs every
+   * StaticPrefs::javascript_options_gc_delay_interslice()
+   */
+  void EnsureGCRunner(TimeDuration aDelay);
+
+  // If GCRunner isn't active, this calls EnsureGCRunner(0). Otherwise the timer
+  // is reset.
+  void EnsureOrResetGCRunner();
+
+  void EnsureCCRunner(TimeDuration aDelay, TimeDuration aBudget);
+
+  // State modification
+
+  void SetNeedsFullGC(bool aNeedGC = true) { mNeedsFullGC = aNeedGC; }
+
+  void SetWantMajorGC(JS::GCReason aReason) {
+    MOZ_ASSERT(aReason != JS::GCReason::NO_REASON);
+
+    // If the GC being requested is not a shrinking GC set this flag.
+    // If/when the shrinking GC timer fires but the user is active we check
+    // this flag before canceling the GC, so as not to cancel the
+    // non-shrinking GC being requested here.
+    if (aReason != JS::GCReason::USER_INACTIVE) {
+      mWantAtLeastRegularGC = true;
+    }
+
+    // Force full GCs when called from reftests so that we collect dead zones
+    // that have not been scheduled for collection.
+    if (aReason == JS::GCReason::DOM_WINDOW_UTILS) {
+      SetNeedsFullGC();
+    }
+
+    // USER_INACTIVE trumps everything,
+    // FULL_GC_TIMER trumps everything except USER_INACTIVE,
+    // all other reasons just use the latest reason.
+    switch (aReason) {
+      case JS::GCReason::USER_INACTIVE:
+        mMajorGCReason = aReason;
+        break;
+      case JS::GCReason::FULL_GC_TIMER:
+        if (mMajorGCReason != JS::GCReason::USER_INACTIVE) {
+          mMajorGCReason = aReason;
+        }
+        break;
+      default:
+        if (mMajorGCReason != JS::GCReason::USER_INACTIVE &&
+            mMajorGCReason != JS::GCReason::FULL_GC_TIMER) {
+          mMajorGCReason = aReason;
+        }
+        break;
+    }
+  }
+
+  void SetWantEagerMinorGC(JS::GCReason aReason) {
+    if (mEagerMinorGCReason == JS::GCReason::NO_REASON) {
+      mEagerMinorGCReason = aReason;
+    }
+  }
+
+  // Ensure that the current runner does a cycle collection, and trigger a GC
+  // after it finishes.
+  void EnsureCCThenGC(CCReason aReason) {
+    MOZ_ASSERT(mCCRunnerState != CCRunnerState::Inactive);
+    MOZ_ASSERT(aReason != CCReason::NO_REASON);
+    mNeedsFullCC = aReason;
+    mNeedsGCAfterCC = true;
+  }
+
+  // Returns false if we started and finished a major GC while waiting for a
+  // response.
+  [[nodiscard]] bool NoteReadyForMajorGC() {
+    if (mMajorGCReason == JS::GCReason::NO_REASON || InIncrementalGC()) {
+      return false;
+    }
+    mReadyForMajorGC = true;
+    return true;
+  }
+
+  // Starting a major GC (incremental or non-incremental).
+  void NoteGCBegin(JS::GCReason aReason);
+
+  // Major GC completed.
+  void NoteGCEnd();
+
+  // A timer fired, but then decided not to run a GC.
+  void NoteWontGC();
+
+  void NoteMinorGCEnd() { mEagerMinorGCReason = JS::GCReason::NO_REASON; }
+
+  // This is invoked when we reach the actual cycle collection portion of the
+  // overall cycle collection.
+  void NoteCCBegin(CCReason aReason, TimeStamp aWhen,
+                   uint32_t aNumForgetSkippables, uint32_t aSuspected,
+                   uint32_t aRemovedPurples);
+
+  // This is invoked when the whole process of collection is done -- i.e., CC
+  // preparation (eg ForgetSkippables) in addition to the CC itself. There
+  // really ought to be a separate name for the overall CC as opposed to the
+  // actual cycle collection portion.
+  void NoteCCEnd(const CycleCollectorResults& aResults, TimeStamp aWhen,
+                 mozilla::TimeDuration aMaxSliceTime);
+
+  // A single slice has completed.
+  void NoteGCSliceEnd(TimeStamp aStart, TimeStamp aEnd);
+
+  bool GCRunnerFired(TimeStamp aDeadline);
+  bool GCRunnerFiredDoGC(TimeStamp aDeadline, const GCRunnerStep& aStep);
+
+  using MayGCPromise =
+      MozPromise<bool, mozilla::ipc::ResponseRejectReason, true>;
+
+  // Returns null if we shouldn't GC now (eg a GC is already running).
+  static RefPtr<MayGCPromise> MayGCNow(JS::GCReason reason);
+
+  // Check all of the various collector timers/runners and see if they are
+  // waiting to fire. This does not check the Full GC Timer, as that's a
+  // more expensive collection we run on a long timer.
+  void RunNextCollectorTimer(JS::GCReason aReason,
+                             mozilla::TimeStamp aDeadline);
+
+  // When we decide to do a cycle collection but we're in the middle of an
+  // incremental GC, the CC is "locked out" until the GC completes -- unless
+  // the wait is too long, and we decide to finish the incremental GC early.
+  void BlockCC(TimeStamp aNow) {
+    MOZ_ASSERT(mInIncrementalGC);
+    MOZ_ASSERT(mCCBlockStart.IsNull());
+    mCCBlockStart = aNow;
+  }
+
+  void UnblockCC() { mCCBlockStart = TimeStamp(); }
+
+  // Returns the number of purple buffer items that were processed and removed.
+  uint32_t NoteForgetSkippableComplete(TimeStamp aNow,
+                                       uint32_t aSuspectedBeforeForgetSkippable,
+                                       uint32_t aSuspectedCCObjects) {
+    mLastForgetSkippableEndTime = aNow;
+    mPreviousSuspectedCount = aSuspectedCCObjects;
+    mCleanupsSinceLastGC++;
+    return aSuspectedBeforeForgetSkippable - aSuspectedCCObjects;
+  }
+
+  // Test if we are in the NoteCCBegin .. NoteCCEnd interval.
+  bool IsCollectingCycles() const { return mIsCollectingCycles; }
+
+  // The CC was abandoned without running a slice, so we only did forget
+  // skippables. Prevent running another cycle soon.
+  void NoteForgetSkippableOnlyCycle(TimeStamp aNow) {
+    mLastForgetSkippableCycleEndTime = aNow;
+  }
+
+  void Shutdown() {
+    mDidShutdown = true;
+    KillAllTimersAndRunners();
+  }
+
+  // Scheduling
+
+  // Return a budget along with a boolean saying whether to prefer to run short
+  // slices and stop rather than continuing to the next phase of cycle
+  // collection.
+  js::SliceBudget ComputeCCSliceBudget(TimeStamp aDeadline,
+                                       TimeStamp aCCBeginTime,
+                                       TimeStamp aPrevSliceEndTime,
+                                       TimeStamp aNow,
+                                       bool* aPreferShorterSlices) const;
+
+  js::SliceBudget ComputeInterSliceGCBudget(TimeStamp aDeadline,
+                                            TimeStamp aNow);
+
+  bool ShouldForgetSkippable(uint32_t aSuspectedCCObjects) const {
+    // Only do a forget skippable if there are more than a few new objects
+    // or we're doing the initial forget skippables.
+    return ((mPreviousSuspectedCount + 100) <= aSuspectedCCObjects) ||
+           mCleanupsSinceLastGC < kMajorForgetSkippableCalls;
+  }
+
+  // There is reason to suspect that there may be a significant amount of
+  // garbage to cycle collect: either we just finished a GC, or the purple
+  // buffer is getting really big, or it's getting somewhat big and it has been
+  // too long since the last CC.
+  CCReason IsCCNeeded(TimeStamp aNow, uint32_t aSuspectedCCObjects) const {
+    if (mNeedsFullCC != CCReason::NO_REASON) {
+      return mNeedsFullCC;
+    }
+    if (aSuspectedCCObjects > kCCPurpleLimit) {
+      return CCReason::MANY_SUSPECTED;
+    }
+    if (aSuspectedCCObjects > kCCForcedPurpleLimit && mLastCCEndTime &&
+        aNow - mLastCCEndTime > kCCForced) {
+      return CCReason::TIMED;
+    }
+    return CCReason::NO_REASON;
+  }
+
+  mozilla::CCReason ShouldScheduleCC(TimeStamp aNow,
+                                     uint32_t aSuspectedCCObjects) const;
+
+  // If we collected a substantial amount of cycles, poke the GC since more
+  // objects might be unreachable now.
+  bool NeedsGCAfterCC() const {
+    return mCCollectedWaitingForGC > 250 || mCCollectedZonesWaitingForGC > 0 ||
+           mLikelyShortLivingObjectsNeedingGC > 2500 || mNeedsGCAfterCC;
+  }
+
+  bool IsLastEarlyCCTimer(int32_t aCurrentFireCount) const {
+    int32_t numEarlyTimerFires =
+        std::max(int32_t(mCCDelay / kCCSkippableDelay) - 2, 1);
+
+    return aCurrentFireCount >= numEarlyTimerFires;
+  }
+
+  enum class CCRunnerState {
+    Inactive,
+    ReducePurple,
+    CleanupChildless,
+    CleanupContentUnbinder,
+    CleanupDeferred,
+    StartCycleCollection,
+    CycleCollecting,
+    Canceled,
+    NumStates
+  };
+
+  void InitCCRunnerStateMachine(CCRunnerState initialState, CCReason aReason) {
+    if (mCCRunner) {
+      return;
+    }
+
+    MOZ_ASSERT(mCCReason == CCReason::NO_REASON);
+    mCCReason = aReason;
+
+    // The state machine should always have been deactivated after the previous
+    // collection, however far that collection may have gone.
+    MOZ_ASSERT(mCCRunnerState == CCRunnerState::Inactive,
+               "DeactivateCCRunner should have been called");
+    mCCRunnerState = initialState;
+
+    // Currently, there are only two entry points to the non-Inactive part of
+    // the state machine.
+    if (initialState == CCRunnerState::ReducePurple) {
+      mCCDelay = kCCDelay;
+      mCCRunnerEarlyFireCount = 0;
+    } else if (initialState == CCRunnerState::CycleCollecting) {
+      // Nothing needed.
+    } else {
+      MOZ_CRASH("Invalid initial state");
+    }
+  }
+
+  void DeactivateCCRunner() {
+    mCCRunnerState = CCRunnerState::Inactive;
+    mCCReason = CCReason::NO_REASON;
+  }
+
+  bool HasMoreIdleGCRunnerWork() const {
+    return mMajorGCReason != JS::GCReason::NO_REASON ||
+           mEagerMajorGCReason != JS::GCReason::NO_REASON ||
+           mEagerMinorGCReason != JS::GCReason::NO_REASON;
+  }
+
+  GCRunnerStep GetNextGCRunnerAction(TimeStamp aDeadline) const;
+
+  CCRunnerStep AdvanceCCRunner(TimeStamp aDeadline, TimeStamp aNow,
+                               uint32_t aSuspectedCCObjects);
+
+  // aStartTimeStamp : when the ForgetSkippable timer fired. This may be some
+  // time ago, if an incremental GC needed to be finished.
+  js::SliceBudget ComputeForgetSkippableBudget(TimeStamp aStartTimeStamp,
+                                               TimeStamp aDeadline);
+
+ private:
+  // State
+
+  // An incremental GC is in progress, which blocks the CC from running for its
+  // duration (or until it goes too long and is finished synchronously.)
+  bool mInIncrementalGC = false;
+
+  // Whether to ask the parent process if now is a good time to GC (false for
+  // the parent process.)
+  const bool mAskParentBeforeMajorGC;
+
+  // We've asked the parent process if now is a good time to GC (do not ask
+  // again).
+  bool mHaveAskedParent = false;
+
+  // The parent process is ready for us to do a major GC.
+  bool mReadyForMajorGC;
+
+  // Set when the IdleTaskRunner requests the current task be interrupted.
+  // Cleared when the GC slice budget has detected the interrupt request.
+  js::SliceBudget::InterruptRequestFlag mInterruptRequested;
+
+  // When a shrinking GC has been requested but we back-out, if this is true
+  // we run a non-shrinking GC.
+  bool mWantAtLeastRegularGC = false;
+
+  // When the CC started actually waiting for the GC to finish. This will be
+  // set to non-null at a later time than mCCLockedOut.
+  TimeStamp mCCBlockStart;
+
+  bool mDidShutdown = false;
+
+  TimeStamp mLastForgetSkippableEndTime;
+  uint32_t mForgetSkippableCounter = 0;
+  TimeStamp mForgetSkippableFrequencyStartTime;
+  TimeStamp mLastCCEndTime;
+  TimeStamp mLastForgetSkippableCycleEndTime;
+
+  CCRunnerState mCCRunnerState = CCRunnerState::Inactive;
+  int32_t mCCRunnerEarlyFireCount = 0;
+  TimeDuration mCCDelay = kCCDelay;
+
+  // Prevent the very first CC from running before we have GC'd and set the
+  // gray bits.
+  bool mHasRunGC = false;
+
+  mozilla::CCReason mNeedsFullCC = CCReason::NO_REASON;
+  bool mNeedsFullGC = true;
+  bool mNeedsGCAfterCC = false;
+  uint32_t mPreviousSuspectedCount = 0;
+
+  uint32_t mCleanupsSinceLastGC = UINT32_MAX;
+
+  // If the GC runner triggers a GC slice, this will be set to the idle deadline
+  // or the null timestamp if non-idle. It will be Nothing at the end of an
+  // internally-triggered slice.
+  mozilla::Maybe<TimeStamp> mTriggeredGCDeadline;
+
+  RefPtr<IdleTaskRunner> mGCRunner;
+  RefPtr<IdleTaskRunner> mCCRunner;
+  nsITimer* mShrinkingGCTimer = nullptr;
+  nsITimer* mFullGCTimer = nullptr;
+
+  mozilla::CCReason mCCReason = mozilla::CCReason::NO_REASON;
+  JS::GCReason mMajorGCReason = JS::GCReason::NO_REASON;
+  JS::GCReason mEagerMajorGCReason = JS::GCReason::NO_REASON;
+  JS::GCReason mEagerMinorGCReason = JS::GCReason::NO_REASON;
+
+  bool mIsCompactingOnUserInactive = false;
+  bool mIsCollectingCycles = false;
+  bool mUserIsActive = true;
+
+ public:
+  uint32_t mCCollectedWaitingForGC = 0;
+  uint32_t mCCollectedZonesWaitingForGC = 0;
+  uint32_t mLikelyShortLivingObjectsNeedingGC = 0;
+
+  // Configuration parameters
+
+  TimeDuration mActiveIntersliceGCBudget = TimeDuration::FromMilliseconds(5);
+};
+
+}  // namespace mozilla