chromium/src/third_party/blink/renderer/platform/bindings/v8_per_context_data.cc

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#include "third_party/blink/renderer/platform/bindings/v8_per_context_data.h"

#include <stdlib.h>
#include <memory>
#include <utility>

#include "base/memory/ptr_util.h"
#include "third_party/blink/renderer/platform/bindings/origin_trial_features.h"
#include "third_party/blink/renderer/platform/bindings/script_state.h"
#include "third_party/blink/renderer/platform/bindings/v8_binding.h"
#include "third_party/blink/renderer/platform/bindings/v8_object_constructor.h"
#include "third_party/blink/renderer/platform/bindings/wrapper_type_info.h"
#include "third_party/blink/renderer/platform/instrumentation/instance_counters.h"

namespace blink {

namespace {

constexpr char kContextLabel[] = "V8PerContextData::context_";

}  // namespace

V8PerContextData::V8PerContextData(v8::Local<v8::Context> context)
    : isolate_(context->GetIsolate()),
      context_holder_(std::make_unique<gin::ContextHolder>(isolate_)),
      context_(isolate_, context),
      activity_logger_(nullptr) {
  context_holder_->SetContext(context);
  context_.Get().AnnotateStrongRetainer(kContextLabel);

  if (IsMainThread()) {
    InstanceCounters::IncrementCounter(
        InstanceCounters::kV8PerContextDataCounter);
  }
}

V8PerContextData::~V8PerContextData() {
  if (IsMainThread()) {
    InstanceCounters::DecrementCounter(
        InstanceCounters::kV8PerContextDataCounter);
  }
}

void V8PerContextData::Dispose() {
  // These fields are not traced by the garbage collector and could contain
  // strong GC roots that prevent `this` from otherwise being collected, so
  // explicitly break any potential cycles in the ownership graph now.
  context_holder_ = nullptr;
  if (!context_.IsEmpty())
    context_.SetPhantom();
  if (!private_custom_element_definition_id_.IsEmpty())
    private_custom_element_definition_id_.SetPhantom();
}

void V8PerContextData::Trace(Visitor* visitor) const {
  visitor->Trace(wrapper_boilerplates_);
  visitor->Trace(constructor_map_);
  visitor->Trace(data_map_);
}

V8PerContextData* V8PerContextData::From(v8::Local<v8::Context> context) {
  return ScriptState::From(context)->PerContextData();
}

v8::Local<v8::Object> V8PerContextData::CreateWrapperFromCacheSlowCase(
    const WrapperTypeInfo* type) {
  DCHECK(!wrapper_boilerplates_.Contains(type));
  v8::Context::Scope scope(GetContext());
  v8::Local<v8::Function> interface_object = ConstructorForType(type);
  CHECK(!interface_object.IsEmpty());
  v8::Local<v8::Object> instance_template =
      V8ObjectConstructor::NewInstance(isolate_, interface_object)
          .ToLocalChecked();

  TraceWrapperV8Reference<v8::Object> traced_wrapper;
  traced_wrapper.Set(isolate_, instance_template);
  wrapper_boilerplates_.insert(type, traced_wrapper);

  return instance_template->Clone();
}

v8::Local<v8::Function> V8PerContextData::ConstructorForTypeSlowCase(
    const WrapperTypeInfo* type) {
  DCHECK(!constructor_map_.Contains(type));
  v8::Local<v8::Context> context = GetContext();
  v8::Context::Scope scope(context);

  v8::Local<v8::Function> parent_interface_object;
  if (type->parent_class) {
    parent_interface_object = ConstructorForType(type->parent_class);
  }

  const DOMWrapperWorld& world = DOMWrapperWorld::World(context);
  v8::Local<v8::Function> interface_object =
      V8ObjectConstructor::CreateInterfaceObject(
          type, context, world, isolate_, parent_interface_object,
          V8ObjectConstructor::CreationMode::kInstallConditionalFeatures);

  TraceWrapperV8Reference<v8::Function> traced_wrapper;
  traced_wrapper.Set(isolate_, interface_object);
  constructor_map_.insert(type, traced_wrapper);

  return interface_object;
}

v8::Local<v8::Object> V8PerContextData::PrototypeForType(
    const WrapperTypeInfo* type) {
  v8::Local<v8::Object> constructor = ConstructorForType(type);
  if (constructor.IsEmpty())
    return v8::Local<v8::Object>();
  v8::Local<v8::Value> prototype_value;
  if (!constructor->Get(GetContext(), V8AtomicString(isolate_, "prototype"))
           .ToLocal(&prototype_value) ||
      !prototype_value->IsObject())
    return v8::Local<v8::Object>();
  return prototype_value.As<v8::Object>();
}

bool V8PerContextData::GetExistingConstructorAndPrototypeForType(
    const WrapperTypeInfo* type,
    v8::Local<v8::Object>* prototype_object,
    v8::Local<v8::Function>* interface_object) {
  auto it = constructor_map_.find(type);
  if (it == constructor_map_.end()) {
    interface_object->Clear();
    prototype_object->Clear();
    return false;
  }
  *interface_object = it->value.NewLocal(isolate_);
  *prototype_object = PrototypeForType(type);
  DCHECK(!prototype_object->IsEmpty());
  return true;
}

void V8PerContextData::AddData(const char* key, Data* data) {
  data_map_.Set(key, data);
}

void V8PerContextData::ClearData(const char* key) {
  data_map_.erase(key);
}

V8PerContextData::Data* V8PerContextData::GetData(const char* key) {
  return data_map_.at(key);
}

}  // namespace blink