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_BLOCKING_UI_THREAD_ASYNC_REQUEST_H_ 6 #define CHROME_BROWSER_ANDROID_PROVIDER_BLOCKING_UI_THREAD_ASYNC_REQUEST_H_ 7 8 #include "base/bind.h" 9 #include "base/callback.h" 10 #include "base/synchronization/waitable_event.h" 11 #include "chrome/browser/android/provider/run_on_ui_thread_blocking.h" 12 #include "content/public/browser/browser_thread.h" 13 14 // Allows making async requests and blocking the current thread until the 15 // response arrives. The request is performed in the UI thread. 16 // Users of this class MUST call RequestCompleted when receiving the response. 17 // Cannot be called directly from the UI thread. 18 class BlockingUIThreadAsyncRequest { 19 public: 20 BlockingUIThreadAsyncRequest(); 21 22 // Runs an asynchronous request, blocking the invoking thread until a response 23 // is received. Class users MUST call RequestCompleted when this happens. 24 // Make sure that the response is also delivered to the UI thread. 25 // The request argument can be defined using base::Bind. 26 template <typename Signature> 27 void RunAsyncRequestOnUIThreadBlocking(base::Callback<Signature> request) { 28 DCHECK(!content::BrowserThread::CurrentlyOn(content::BrowserThread::UI)); 29 30 // Make the request in the UI thread. 31 request_completed_.Reset(); 32 RunOnUIThreadBlocking::Run( 33 base::Bind( 34 &BlockingUIThreadAsyncRequest::RunRequestOnUIThread<Signature>, 35 request)); 36 37 // Wait until the request callback invokes Finished. 38 request_completed_.Wait(); 39 } 40 41 // Notifies about a finished request. 42 void RequestCompleted(); 43 44 private: 45 template <typename Signature> 46 static void RunRequestOnUIThread(base::Callback<Signature> request) { 47 request.Run(); 48 } 49 50 base::WaitableEvent request_completed_; 51 52 DISALLOW_COPY_AND_ASSIGN(BlockingUIThreadAsyncRequest); 53 }; 54 55 #endif // CHROME_BROWSER_ANDROID_PROVIDER_BLOCKING_UI_THREAD_ASYNC_REQUEST_H_ 56