1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CHROME_BROWSER_ANDROID_PROVIDER_RUN_ON_UI_THREAD_BLOCKING_H_
6#define CHROME_BROWSER_ANDROID_PROVIDER_RUN_ON_UI_THREAD_BLOCKING_H_
7
8#include "base/bind.h"
9#include "base/callback.h"
10#include "base/synchronization/waitable_event.h"
11#include "content/public/browser/browser_thread.h"
12
13// Runs code synchronously on the UI thread. Should never be called directly
14// from the UI thread. To be used only within the provider classes.
15class RunOnUIThreadBlocking {
16 public:
17  // Runs the provided runnable in the UI thread synchronously.
18  // The runnable argument can be defined using base::Bind.
19  template <typename Signature>
20  static void Run(base::Callback<Signature> runnable) {
21    DCHECK(!content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
22    base::WaitableEvent finished(false, false);
23    content::BrowserThread::PostTask(content::BrowserThread::UI, FROM_HERE,
24          base::Bind(&RunOnUIThreadBlocking::RunOnUIThread<Signature>,
25                     runnable, &finished));
26    finished.Wait();
27  }
28
29 private:
30  template <typename Signature>
31  static void RunOnUIThread(base::Callback<Signature> runnable,
32                            base::WaitableEvent* finished) {
33    DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
34    runnable.Run();
35    finished->Signal();
36  }
37};
38
39#endif  // CHROME_BROWSER_ANDROID_PROVIDER_RUN_ON_UI_THREAD_BLOCKING_H_
40