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// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/platform/heap/unified_heap_controller.h"
#include "base/macros.h"
#include "third_party/blink/public/common/features.h"
#include "third_party/blink/renderer/platform/bindings/dom_wrapper_world.h"
#include "third_party/blink/renderer/platform/bindings/script_forbidden_scope.h"
#include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
#include "third_party/blink/renderer/platform/bindings/wrapper_type_info.h"
#include "third_party/blink/renderer/platform/heap/heap.h"
#include "third_party/blink/renderer/platform/heap/heap_stats_collector.h"
#include "third_party/blink/renderer/platform/heap/impl/marking_visitor.h"
#include "third_party/blink/renderer/platform/heap/thread_state.h"
#include "third_party/blink/renderer/platform/runtime_enabled_features.h"
namespace blink {
namespace {
constexpr BlinkGC::StackState ToBlinkGCStackState(
v8::EmbedderHeapTracer::EmbedderStackState stack_state) {
return stack_state ==
v8::EmbedderHeapTracer::EmbedderStackState::kNoHeapPointers
? BlinkGC::kNoHeapPointersOnStack
: BlinkGC::kHeapPointersOnStack;
}
} // namespace
UnifiedHeapController::UnifiedHeapController(ThreadState* thread_state)
: thread_state_(thread_state) {
thread_state->Heap().stats_collector()->RegisterObserver(this);
}
UnifiedHeapController::~UnifiedHeapController() {
thread_state_->Heap().stats_collector()->UnregisterObserver(this);
}
void UnifiedHeapController::TracePrologue(
v8::EmbedderHeapTracer::TraceFlags v8_flags) {
VLOG(2) << "UnifiedHeapController::TracePrologue";
ThreadHeapStatsCollector::BlinkGCInV8Scope nested_scope(
thread_state_->Heap().stats_collector());
// Be conservative here as a new garbage collection gets started right away.
thread_state_->FinishIncrementalMarkingIfRunning(
BlinkGC::CollectionType::kMajor, BlinkGC::kHeapPointersOnStack,
BlinkGC::kIncrementalAndConcurrentMarking,
BlinkGC::kConcurrentAndLazySweeping,
thread_state_->current_gc_data_.reason);
thread_state_->SetGCState(ThreadState::kNoGCScheduled);
BlinkGC::GCReason gc_reason;
if (v8_flags & v8::EmbedderHeapTracer::TraceFlags::kForced) {
gc_reason = BlinkGC::GCReason::kUnifiedHeapForcedForTestingGC;
} else if (v8_flags & v8::EmbedderHeapTracer::TraceFlags::kReduceMemory) {
gc_reason = BlinkGC::GCReason::kUnifiedHeapForMemoryReductionGC;
} else {
gc_reason = BlinkGC::GCReason::kUnifiedHeapGC;
}
thread_state_->StartIncrementalMarking(gc_reason);
is_tracing_done_ = false;
}
void UnifiedHeapController::EnterFinalPause(EmbedderStackState stack_state) {
VLOG(2) << "UnifiedHeapController::EnterFinalPause";
ThreadHeapStatsCollector::BlinkGCInV8Scope nested_scope(
thread_state_->Heap().stats_collector());
thread_state_->AtomicPauseMarkPrologue(
BlinkGC::CollectionType::kMajor, ToBlinkGCStackState(stack_state),
BlinkGC::kIncrementalAndConcurrentMarking,
thread_state_->current_gc_data_.reason);
thread_state_->AtomicPauseMarkRoots(ToBlinkGCStackState(stack_state),
BlinkGC::kIncrementalAndConcurrentMarking,
thread_state_->current_gc_data_.reason);
}
void UnifiedHeapController::TraceEpilogue(
v8::EmbedderHeapTracer::TraceSummary* summary) {
VLOG(2) << "UnifiedHeapController::TraceEpilogue";
{
ThreadHeapStatsCollector::BlinkGCInV8Scope nested_scope(
thread_state_->Heap().stats_collector());
thread_state_->AtomicPauseMarkEpilogue(
BlinkGC::kIncrementalAndConcurrentMarking);
const BlinkGC::SweepingType sweeping_type =
thread_state_->IsForcedGC() ? BlinkGC::kEagerSweeping
: BlinkGC::kConcurrentAndLazySweeping;
thread_state_->AtomicPauseSweepAndCompact(
BlinkGC::CollectionType::kMajor,
BlinkGC::kIncrementalAndConcurrentMarking, sweeping_type);
ThreadHeapStatsCollector* const stats_collector =
thread_state_->Heap().stats_collector();
summary->allocated_size =
static_cast<size_t>(stats_collector->marked_bytes());
summary->time = stats_collector->marking_time_so_far().InMillisecondsF();
buffered_allocated_size_ = 0;
}
thread_state_->AtomicPauseEpilogue();
}
void UnifiedHeapController::RegisterV8References(
const std::vector<std::pair<void*, void*>>&
internal_fields_of_potential_wrappers) {
VLOG(2) << "UnifiedHeapController::RegisterV8References";
DCHECK(thread_state()->IsMarkingInProgress());
const bool was_in_atomic_pause = thread_state()->in_atomic_pause();
if (!was_in_atomic_pause)
ThreadState::Current()->EnterAtomicPause();
for (const auto& internal_fields : internal_fields_of_potential_wrappers) {
const WrapperTypeInfo* wrapper_type_info =
reinterpret_cast<const WrapperTypeInfo*>(internal_fields.first);
if (wrapper_type_info->gin_embedder != gin::GinEmbedder::kEmbedderBlink) {
continue;
}
is_tracing_done_ = false;
wrapper_type_info->Trace(thread_state_->CurrentVisitor(),
internal_fields.second);
}
if (!was_in_atomic_pause)
ThreadState::Current()->LeaveAtomicPause();
}
bool UnifiedHeapController::AdvanceTracing(double deadline_in_ms) {
VLOG(2) << "UnifiedHeapController::AdvanceTracing";
ThreadHeapStatsCollector::BlinkGCInV8Scope nested_scope(
thread_state_->Heap().stats_collector());
if (!thread_state_->in_atomic_pause()) {
ThreadHeapStatsCollector::EnabledScope advance_tracing_scope(
thread_state_->Heap().stats_collector(),
ThreadHeapStatsCollector::kUnifiedMarkingStep);
// V8 calls into embedder tracing from its own marking to ensure
// progress. Oilpan will additionally schedule marking steps.
ThreadState::AtomicPauseScope atomic_pause_scope(thread_state_);
ScriptForbiddenScope script_forbidden_scope;
is_tracing_done_ = thread_state_->MarkPhaseAdvanceMarkingBasedOnSchedule(
base::TimeDelta::FromMillisecondsD(deadline_in_ms),
ThreadState::EphemeronProcessing::kPartialProcessing);
if (!is_tracing_done_) {
if (base::FeatureList::IsEnabled(
blink::features::kBlinkHeapConcurrentMarking)) {
thread_state_->ConcurrentMarkingStep();
}
thread_state_->RestartIncrementalMarkingIfPaused();
}
return is_tracing_done_;
}
thread_state_->AtomicPauseMarkTransitiveClosure();
is_tracing_done_ = true;
return true;
}
bool UnifiedHeapController::IsTracingDone() {
return is_tracing_done_;
}
bool UnifiedHeapController::IsRootForNonTracingGC(
const v8::TracedReference<v8::Value>& handle) {
if (thread_state()->IsIncrementalMarking()) {
// We have a non-tracing GC while unified GC is in progress. Treat all
// objects as roots to avoid stale pointers in the marking worklists.
return true;
}
const uint16_t class_id = handle.WrapperClassId();
// Stand-alone reference or kCustomWrappableId. Keep as root as
// we don't know better.
if (class_id != WrapperTypeInfo::kNodeClassId &&
class_id != WrapperTypeInfo::kObjectClassId)
return true;
const v8::TracedReference<v8::Object>& traced =
handle.template As<v8::Object>();
if (ToWrapperTypeInfo(traced)->IsActiveScriptWrappable() &&
ToScriptWrappable(traced)->HasPendingActivity()) {
return true;
}
if (ToScriptWrappable(traced)->HasEventListeners()) {
return true;
}
return false;
}
void UnifiedHeapController::ResetHandleInNonTracingGC(
const v8::TracedReference<v8::Value>& handle) {
const uint16_t class_id = handle.WrapperClassId();
// Only consider handles that have not been treated as roots, see
// IsRootForNonTracingGCInternal.
if (class_id != WrapperTypeInfo::kNodeClassId &&
class_id != WrapperTypeInfo::kObjectClassId)
return;
// We should not reset any handles during an already running tracing
// collection. Resetting a handle could re-allocate a backing or trigger
// potential in place rehashing. Both operations may trigger write barriers by
// moving references. Such references may already be dead but not yet cleared
// which would result in reporting dead objects to V8.
DCHECK(!thread_state()->IsIncrementalMarking());
// Clearing the wrapper below adjusts the DOM wrapper store which may
// re-allocate its backing. We have to avoid report memory to V8 as that may
// trigger GC during GC.
ThreadState::GCForbiddenScope gc_forbidden(thread_state());
const v8::TracedReference<v8::Object>& traced = handle.As<v8::Object>();
bool success = DOMWrapperWorld::UnsetSpecificWrapperIfSet(
ToScriptWrappable(traced), traced);
// Since V8 found a handle, Blink needs to find it as well when trying to
// remove it.
CHECK(success);
}
bool UnifiedHeapController::IsRootForNonTracingGC(
const v8::TracedGlobal<v8::Value>& handle) {
CHECK(false) << "Blink does not use v8::TracedGlobal.";
return false;
}
void UnifiedHeapController::ReportBufferedAllocatedSizeIfPossible() {
// Avoid reporting to V8 in the following conditions as that may trigger GC
// finalizations where not allowed.
// - Recursive sweeping.
// - GC forbidden scope.
if ((thread_state()->IsSweepingInProgress() &&
thread_state()->SweepForbidden()) ||
thread_state()->IsGCForbidden()) {
return;
}
if (buffered_allocated_size_ < 0) {
DecreaseAllocatedSize(static_cast<size_t>(-buffered_allocated_size_));
} else {
IncreaseAllocatedSize(static_cast<size_t>(buffered_allocated_size_));
}
buffered_allocated_size_ = 0;
}
void UnifiedHeapController::IncreaseAllocatedObjectSize(size_t delta_bytes) {
buffered_allocated_size_ += static_cast<int64_t>(delta_bytes);
ReportBufferedAllocatedSizeIfPossible();
}
void UnifiedHeapController::DecreaseAllocatedObjectSize(size_t delta_bytes) {
buffered_allocated_size_ -= static_cast<int64_t>(delta_bytes);
ReportBufferedAllocatedSizeIfPossible();
}
} // namespace blink
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