src/heap/embedder-tracing.cc

// Copyright 2016 the V8 project 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 "src/heap/embedder-tracing.h"

#include "src/base/logging.h"
#include "src/objects/embedder-data-slot.h"
#include "src/objects/js-objects-inl.h"

namespace v8 {
namespace internal {

void LocalEmbedderHeapTracer::SetRemoteTracer(EmbedderHeapTracer* tracer) {
  if (remote_tracer_) remote_tracer_->isolate_ = nullptr;

  remote_tracer_ = tracer;
  if (remote_tracer_)
    remote_tracer_->isolate_ = reinterpret_cast<v8::Isolate*>(isolate_);
}

void LocalEmbedderHeapTracer::TracePrologue(
    EmbedderHeapTracer::TraceFlags flags) {
  if (!InUse()) return;

  num_v8_marking_worklist_was_empty_ = 0;
  embedder_worklist_empty_ = false;
  remote_tracer_->TracePrologue(flags);
}

void LocalEmbedderHeapTracer::TraceEpilogue() {
  if (!InUse()) return;

  remote_tracer_->TraceEpilogue();
}

void LocalEmbedderHeapTracer::EnterFinalPause() {
  if (!InUse()) return;

  remote_tracer_->EnterFinalPause(embedder_stack_state_);
  // Resetting to state unknown as there may be follow up garbage collections
  // triggered from callbacks that have a different stack state.
  embedder_stack_state_ = EmbedderHeapTracer::kUnknown;
}

bool LocalEmbedderHeapTracer::Trace(double deadline) {
  if (!InUse()) return true;

  return remote_tracer_->AdvanceTracing(deadline);
}

bool LocalEmbedderHeapTracer::IsRemoteTracingDone() {
  return !InUse() || remote_tracer_->IsTracingDone();
}

void LocalEmbedderHeapTracer::SetEmbedderStackStateForNextFinalization(
    EmbedderHeapTracer::EmbedderStackState stack_state) {
  if (!InUse()) return;

  embedder_stack_state_ = stack_state;
}

LocalEmbedderHeapTracer::ProcessingScope::ProcessingScope(
    LocalEmbedderHeapTracer* tracer)
    : tracer_(tracer) {
  wrapper_cache_.reserve(kWrapperCacheSize);
}

LocalEmbedderHeapTracer::ProcessingScope::~ProcessingScope() {
  if (!wrapper_cache_.empty()) {
    tracer_->remote_tracer()->RegisterV8References(std::move(wrapper_cache_));
  }
}

void LocalEmbedderHeapTracer::ProcessingScope::TracePossibleWrapper(
    JSObject js_object) {
  DCHECK(js_object->IsApiWrapper());
  if (js_object->GetEmbedderFieldCount() < 2) return;

  void* pointer0;
  void* pointer1;
  if (EmbedderDataSlot(js_object, 0).ToAlignedPointer(&pointer0) && pointer0 &&
      EmbedderDataSlot(js_object, 1).ToAlignedPointer(&pointer1)) {
    wrapper_cache_.push_back({pointer0, pointer1});
  }
  FlushWrapperCacheIfFull();
}

void LocalEmbedderHeapTracer::ProcessingScope::FlushWrapperCacheIfFull() {
  if (wrapper_cache_.size() == wrapper_cache_.capacity()) {
    tracer_->remote_tracer()->RegisterV8References(std::move(wrapper_cache_));
    wrapper_cache_.clear();
    wrapper_cache_.reserve(kWrapperCacheSize);
  }
}

void LocalEmbedderHeapTracer::ProcessingScope::AddWrapperInfoForTesting(
    WrapperInfo info) {
  wrapper_cache_.push_back(info);
  FlushWrapperCacheIfFull();
}

}  // namespace internal
}  // namespace v8