cef/tests/shared/browser/main_message_loop.h

// Copyright (c) 2015 The Chromium Embedded Framework Authors. All rights
// reserved. Use of this source code is governed by a BSD-style license that
// can be found in the LICENSE file.

#ifndef CEF_TESTS_SHARED_BROWSER_MAIN_MESSAGE_LOOP_H_
#define CEF_TESTS_SHARED_BROWSER_MAIN_MESSAGE_LOOP_H_
#pragma once

#include <memory>

#include "include/base/cef_callback.h"
#include "include/cef_task.h"

#if defined(OS_WIN)
#include <windows.h>
#endif

namespace client {

// Represents the message loop running on the main application thread in the
// browser process. This will be the same as the CEF UI thread on Linux, OS X
// and Windows when not using multi-threaded message loop mode. The methods of
// this class are thread-safe unless otherwise indicated.
class MainMessageLoop {
 public:
  // Returns the singleton instance of this object.
  static MainMessageLoop* Get();

  // Run the message loop. The thread that this method is called on will be
  // considered the main thread. This blocks until Quit() is called.
  virtual int Run() = 0;

  // Quit the message loop.
  virtual void Quit() = 0;

  // Post a task for execution on the main message loop.
  virtual void PostTask(CefRefPtr<CefTask> task) = 0;

  // Returns true if this message loop runs tasks on the current thread.
  virtual bool RunsTasksOnCurrentThread() const = 0;

#if defined(OS_WIN)
  // Set the current modeless dialog on Windows for proper delivery of dialog
  // messages when using multi-threaded message loop mode. This method must be
  // called from the main thread. See http://support.microsoft.com/kb/71450 for
  // background.
  virtual void SetCurrentModelessDialog(HWND hWndDialog) = 0;
#endif

  // Post a closure for execution on the main message loop.
  void PostClosure(base::OnceClosure closure);
  void PostClosure(const base::RepeatingClosure& closure);

 protected:
  // Only allow deletion via std::unique_ptr.
  friend std::default_delete<MainMessageLoop>;

  MainMessageLoop();
  virtual ~MainMessageLoop();

 private:
  DISALLOW_COPY_AND_ASSIGN(MainMessageLoop);
};

#define CURRENTLY_ON_MAIN_THREAD() \
  client::MainMessageLoop::Get()->RunsTasksOnCurrentThread()

#define REQUIRE_MAIN_THREAD() DCHECK(CURRENTLY_ON_MAIN_THREAD())

#define MAIN_POST_TASK(task) client::MainMessageLoop::Get()->PostTask(task)

#define MAIN_POST_CLOSURE(closure) \
  client::MainMessageLoop::Get()->PostClosure(closure)

// Use this struct in conjuction with RefCountedThreadSafe to ensure that an
// object is deleted on the main thread. For example:
//
// class Foo : public base::RefCountedThreadSafe<Foo, DeleteOnMainThread> {
//  public:
//   Foo();
//   void DoSomething();
//
//  private:
//   // Allow deletion via scoped_refptr only.
//   friend struct DeleteOnMainThread;
//   friend class base::RefCountedThreadSafe<Foo, DeleteOnMainThread>;
//
//   virtual ~Foo() {}
// };
//
// base::scoped_refptr<Foo> foo = new Foo();
// foo->DoSomething();
// foo = nullptr;  // Deletion of |foo| will occur on the main thread.
//
struct DeleteOnMainThread {
  template <typename T>
  static void Destruct(const T* x) {
    if (CURRENTLY_ON_MAIN_THREAD()) {
      delete x;
    } else {
      client::MainMessageLoop::Get()->PostClosure(base::BindOnce(
          &DeleteOnMainThread::Destruct<T>, base::Unretained(x)));
    }
  }
};

}  // namespace client

#endif  // CEF_TESTS_SHARED_BROWSER_MAIN_MESSAGE_LOOP_H_