1/*
2 *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10
11#ifndef WEBRTC_SYSTEM_WRAPPERS_INCLUDE_EVENT_WRAPPER_H_
12#define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_EVENT_WRAPPER_H_
13
14namespace webrtc {
15enum EventTypeWrapper {
16  kEventSignaled = 1,
17  kEventError = 2,
18  kEventTimeout = 3
19};
20
21#define WEBRTC_EVENT_INFINITE 0xffffffff
22
23class EventTimerWrapper;
24
25class EventWrapper {
26 public:
27  // Factory method. Constructor disabled.
28  static EventWrapper* Create();
29
30  virtual ~EventWrapper() {}
31
32  // Releases threads who are calling Wait() and has started waiting. Please
33  // note that a thread calling Wait() will not start waiting immediately.
34  // assumptions to the contrary is a very common source of issues in
35  // multithreaded programming.
36  // Set is sticky in the sense that it will release at least one thread
37  // either immediately or some time in the future.
38  virtual bool Set() = 0;
39
40  // Puts the calling thread into a wait state. The thread may be released
41  // by a Set() call depending on if other threads are waiting and if so on
42  // timing. The thread that was released will reset the event before leaving
43  // preventing more threads from being released. If multiple threads
44  // are waiting for the same Set(), only one (random) thread is guaranteed to
45  // be released. It is possible that multiple (random) threads are released
46  // Depending on timing.
47  //
48  // |max_time| is the maximum time to wait in milliseconds or
49  // WEBRTC_EVENT_INFINITE to wait infinitely.
50  virtual EventTypeWrapper Wait(unsigned long max_time) = 0;
51};
52
53class EventTimerWrapper : public EventWrapper {
54 public:
55  static EventTimerWrapper* Create();
56
57  // Starts a timer that will call a non-sticky version of Set() either once
58  // or periodically. If the timer is periodic it ensures that there is no
59  // drift over time relative to the system clock.
60  //
61  // |time| is in milliseconds.
62  virtual bool StartTimer(bool periodic, unsigned long time) = 0;
63
64  virtual bool StopTimer() = 0;
65
66};
67
68}  // namespace webrtc
69
70#endif  // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_EVENT_WRAPPER_H_
71