1 // Copyright 2013 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 MOJO_COMMON_HANDLE_WATCHER_H_ 6 #define MOJO_COMMON_HANDLE_WATCHER_H_ 7 8 #include "base/basictypes.h" 9 #include "base/callback_forward.h" 10 #include "base/memory/scoped_ptr.h" 11 #include "base/run_loop.h" 12 #include "mojo/common/mojo_common_export.h" 13 #include "mojo/public/cpp/system/core.h" 14 15 namespace base { 16 class Thread; 17 } 18 19 namespace mojo { 20 namespace common { 21 namespace test { 22 class HandleWatcherTest; 23 } 24 25 // HandleWatcher is used to asynchronously wait on a handle and notify a Closure 26 // when the handle is ready, or the deadline has expired. 27 class MOJO_COMMON_EXPORT HandleWatcher { 28 public: 29 HandleWatcher(); 30 31 // The destructor implicitly stops listening. See Stop() for details. 32 ~HandleWatcher(); 33 34 // Starts listening for |handle|. This implicitly invokes Stop(). In other 35 // words, Start() performs one asynchronous watch at a time. It is ok to call 36 // Start() multiple times, but it cancels any existing watches. |callback| is 37 // notified when the handle is ready, invalid or deadline has passed and is 38 // notified on the thread Start() was invoked on. If the current thread exits 39 // before the handle is ready, then |callback| is invoked with a result of 40 // MOJO_RESULT_ABORTED. 41 void Start(const Handle& handle, 42 MojoHandleSignals handle_signals, 43 MojoDeadline deadline, 44 const base::Callback<void(MojoResult)>& callback); 45 46 // Stops listening. Does nothing if not in the process of listening. Blocks 47 // until no longer listening on the handle. 48 void Stop(); 49 50 private: 51 class StateBase; 52 class SameThreadWatchingState; 53 class SecondaryThreadWatchingState; 54 55 // If non-NULL Start() has been invoked. 56 scoped_ptr<StateBase> state_; 57 58 DISALLOW_COPY_AND_ASSIGN(HandleWatcher); 59 }; 60 61 } // namespace common 62 } // namespace mojo 63 64 #endif // MOJO_COMMON_HANDLE_WATCHER_H_ 65