chrome/browser/android/provider/run_on_ui_thread_blocking.h

   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.
  15 class 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_