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// Copyright 2016 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 "extensions/renderer/api_event_handler.h"
#include <algorithm>
#include <map>
#include <memory>
#include <vector>
#include "base/bind.h"
#include "base/logging.h"
#include "base/memory/ptr_util.h"
#include "base/supports_user_data.h"
#include "base/values.h"
#include "content/public/child/v8_value_converter.h"
#include "extensions/renderer/event_emitter.h"
#include "gin/handle.h"
#include "gin/per_context_data.h"
namespace extensions {
namespace {
const char kExtensionAPIEventPerContextKey[] = "extension_api_events";
struct APIEventPerContextData : public base::SupportsUserData::Data {
APIEventPerContextData(v8::Isolate* isolate) : isolate(isolate) {}
~APIEventPerContextData() override {
v8::HandleScope scope(isolate);
// We explicitly clear the event data map here to remove all references to
// v8 objects. This helps us avoid cycles in v8 where an event listener
// could hold a reference to the event, which in turn holds the reference
// to the listener.
for (const auto& pair : event_data) {
EventEmitter* emitter = nullptr;
gin::Converter<EventEmitter*>::FromV8(
isolate, pair.second.Get(isolate), &emitter);
CHECK(emitter);
emitter->listeners()->clear();
}
}
// The associated v8::Isolate. Since this object is cleaned up at context
// destruction, this should always be valid.
v8::Isolate* isolate;
// A map from event name -> event emitter.
std::map<std::string, v8::Global<v8::Object>> event_data;
};
} // namespace
APIEventHandler::APIEventHandler(
const binding::RunJSFunction& call_js,
const EventListenersChangedMethod& listeners_changed)
: call_js_(call_js), listeners_changed_(listeners_changed) {}
APIEventHandler::~APIEventHandler() {}
v8::Local<v8::Object> APIEventHandler::CreateEventInstance(
const std::string& event_name,
v8::Local<v8::Context> context) {
// We need a context scope since gin::CreateHandle only takes the isolate
// and infers the context from that.
// TODO(devlin): This could be avoided if gin::CreateHandle could take a
// context directly.
v8::Context::Scope context_scope(context);
gin::PerContextData* per_context_data = gin::PerContextData::From(context);
DCHECK(per_context_data);
APIEventPerContextData* data = static_cast<APIEventPerContextData*>(
per_context_data->GetUserData(kExtensionAPIEventPerContextKey));
if (!data) {
auto api_data =
base::MakeUnique<APIEventPerContextData>(context->GetIsolate());
data = api_data.get();
per_context_data->SetUserData(kExtensionAPIEventPerContextKey,
api_data.release());
}
DCHECK(data->event_data.find(event_name) == data->event_data.end());
gin::Handle<EventEmitter> emitter_handle = gin::CreateHandle(
context->GetIsolate(),
new EventEmitter(call_js_, base::Bind(listeners_changed_, event_name)));
CHECK(!emitter_handle.IsEmpty());
v8::Local<v8::Value> emitter_value = emitter_handle.ToV8();
CHECK(emitter_value->IsObject());
v8::Local<v8::Object> emitter_object =
v8::Local<v8::Object>::Cast(emitter_value);
data->event_data[event_name] =
v8::Global<v8::Object>(context->GetIsolate(), emitter_object);
return emitter_object;
}
void APIEventHandler::FireEventInContext(const std::string& event_name,
v8::Local<v8::Context> context,
const base::ListValue& args) {
gin::PerContextData* per_context_data = gin::PerContextData::From(context);
DCHECK(per_context_data);
APIEventPerContextData* data = static_cast<APIEventPerContextData*>(
per_context_data->GetUserData(kExtensionAPIEventPerContextKey));
if (!data)
return;
auto iter = data->event_data.find(event_name);
if (iter == data->event_data.end())
return;
// Note: since we only convert the arguments once, if a listener modifies an
// object (including an array), other listeners will see that modification.
// TODO(devlin): This is how it's always been, but should it be?
std::vector<v8::Local<v8::Value>> v8_args;
v8_args.reserve(args.GetSize());
std::unique_ptr<content::V8ValueConverter> converter(
content::V8ValueConverter::create());
for (const auto& arg : args)
v8_args.push_back(converter->ToV8Value(arg.get(), context));
EventEmitter* emitter = nullptr;
gin::Converter<EventEmitter*>::FromV8(
context->GetIsolate(), iter->second.Get(context->GetIsolate()), &emitter);
CHECK(emitter);
emitter->Fire(context, &v8_args);
}
size_t APIEventHandler::GetNumEventListenersForTesting(
const std::string& event_name,
v8::Local<v8::Context> context) {
gin::PerContextData* per_context_data = gin::PerContextData::From(context);
DCHECK(per_context_data);
APIEventPerContextData* data = static_cast<APIEventPerContextData*>(
per_context_data->GetUserData(kExtensionAPIEventPerContextKey));
DCHECK(data);
auto iter = data->event_data.find(event_name);
DCHECK(iter != data->event_data.end());
EventEmitter* emitter = nullptr;
gin::Converter<EventEmitter*>::FromV8(
context->GetIsolate(), iter->second.Get(context->GetIsolate()), &emitter);
CHECK(emitter);
return emitter->listeners()->size();
}
} // namespace extensions
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