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 14 namespace webrtc { 15 enum EventTypeWrapper { 16 kEventSignaled = 1, 17 kEventError = 2, 18 kEventTimeout = 3 19 }; 20 21 #define WEBRTC_EVENT_INFINITE 0xffffffff 22 23 class EventTimerWrapper; 24 25 class EventWrapper { 26 public: 27 // Factory method. Constructor disabled. 28 static EventWrapper* Create(); 29 ~EventWrapper()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 53 class 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