electron/shell/common/api/remote_object_freer.cc

// Copyright (c) 2016 GitHub, Inc.
// Use of this source code is governed by the MIT license that can be
// found in the LICENSE file.

#include "shell/common/api/remote_object_freer.h"

#include "base/strings/utf_string_conversions.h"
#include "base/values.h"
#include "content/public/renderer/render_frame.h"
#include "electron/shell/common/api/api.mojom.h"
#include "third_party/blink/public/common/associated_interfaces/associated_interface_provider.h"
#include "third_party/blink/public/web/web_local_frame.h"

using blink::WebLocalFrame;

namespace electron {

namespace {

content::RenderFrame* GetCurrentRenderFrame() {
  WebLocalFrame* frame = WebLocalFrame::FrameForCurrentContext();
  if (!frame)
    return nullptr;

  return content::RenderFrame::FromWebFrame(frame);
}

}  // namespace

// static
void RemoteObjectFreer::BindTo(v8::Isolate* isolate,
                               v8::Local<v8::Object> target,
                               const std::string& context_id,
                               int object_id) {
  new RemoteObjectFreer(isolate, target, context_id, object_id);
}

// static
void RemoteObjectFreer::AddRef(const std::string& context_id, int object_id) {
  ref_mapper_[context_id][object_id]++;
}

// static
std::map<std::string, std::map<int, int>> RemoteObjectFreer::ref_mapper_;

RemoteObjectFreer::RemoteObjectFreer(v8::Isolate* isolate,
                                     v8::Local<v8::Object> target,
                                     const std::string& context_id,
                                     int object_id)
    : ObjectLifeMonitor(isolate, target),
      context_id_(context_id),
      object_id_(object_id),
      routing_id_(MSG_ROUTING_NONE) {
  content::RenderFrame* render_frame = GetCurrentRenderFrame();
  if (render_frame) {
    routing_id_ = render_frame->GetRoutingID();
  }
}

RemoteObjectFreer::~RemoteObjectFreer() {}

void RemoteObjectFreer::RunDestructor() {
  content::RenderFrame* render_frame =
      content::RenderFrame::FromRoutingID(routing_id_);
  if (!render_frame)
    return;

  // Reset our local ref count in case we are in a GC race condition
  // and will get more references in an inbound IPC message
  int ref_count = 0;
  const auto objects_it = ref_mapper_.find(context_id_);
  if (objects_it != std::end(ref_mapper_)) {
    auto& objects = objects_it->second;
    const auto ref_it = objects.find(object_id_);
    if (ref_it != std::end(objects)) {
      ref_count = ref_it->second;
      objects.erase(ref_it);
    }
    if (objects.empty())
      ref_mapper_.erase(objects_it);
  }

  auto* channel = "ELECTRON_BROWSER_DEREFERENCE";

  base::ListValue args;
  args.AppendString(context_id_);
  args.AppendInteger(object_id_);
  args.AppendInteger(ref_count);

  mojom::ElectronBrowserAssociatedPtr electron_ptr;
  render_frame->GetRemoteAssociatedInterfaces()->GetInterface(
      mojo::MakeRequest(&electron_ptr));
  electron_ptr->Message(true, channel, args.Clone());
}

}  // namespace electron