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_INTERFACE_EVENT_WRAPPER_H_
12#define WEBRTC_SYSTEM_WRAPPERS_INTERFACE_EVENT_WRAPPER_H_
13
14namespace webrtc {
15enum EventTypeWrapper
16{
17    kEventSignaled = 1,
18    kEventError = 2,
19    kEventTimeout = 3
20};
21
22#define WEBRTC_EVENT_10_SEC   10000
23#define WEBRTC_EVENT_INFINITE 0xffffffff
24
25class EventWrapper
26{
27public:
28    // Factory method. Constructor disabled.
29    static EventWrapper* Create();
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    // Prevents future Wait() calls from finishing without a new Set() call.
41    virtual bool Reset() = 0;
42
43    // Puts the calling thread into a wait state. The thread may be released
44    // by a Set() call depending on if other threads are waiting and if so on
45    // timing. The thread that was released will call Reset() before leaving
46    // preventing more threads from being released. If multiple threads
47    // are waiting for the same Set(), only one (random) thread is guaranteed to
48    // be released. It is possible that multiple (random) threads are released
49    // Depending on timing.
50    virtual EventTypeWrapper Wait(unsigned long maxTime) = 0;
51
52    // Starts a timer that will call a non-sticky version of Set() either once
53    // or periodically. If the timer is periodic it ensures that there is no
54    // drift over time relative to the system clock.
55    virtual bool StartTimer(bool periodic, unsigned long time) = 0;
56
57    virtual bool StopTimer() = 0;
58
59    // Only implemented on Windows
60    // Returns 1 if a key has been pressed since last call to this function.
61    // -1 indicates failure
62    // 0 indicates no key has been pressed since last call
63    // TODO(hellner) this function does not seem to belong here
64    static int KeyPressed();
65};
66} // namespace webrtc
67
68#endif // WEBRTC_SYSTEM_WRAPPERS_INTERFACE_EVENT_WRAPPER_H_
69