1 // The MIT License (MIT)
2 //
3 // 	Copyright (c) 2015 Sergey Makeev, Vadim Slyusarev
4 //
5 // 	Permission is hereby granted, free of charge, to any person obtaining a copy
6 // 	of this software and associated documentation files (the "Software"), to deal
7 // 	in the Software without restriction, including without limitation the rights
8 // 	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 // 	copies of the Software, and to permit persons to whom the Software is
10 // 	furnished to do so, subject to the following conditions:
11 //
12 //  The above copyright notice and this permission notice shall be included in
13 // 	all copies or substantial portions of the Software.
14 //
15 // 	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 // 	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 // 	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 // 	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 // 	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 // 	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
21 // 	THE SOFTWARE.
22 
23 #pragma once
24 
25 #ifndef __MT_EVENT_USER__
26 #define __MT_EVENT_USER__
27 
28 namespace MT
29 {
30 	//
31 	//
32 	//
33 	class Event
34 	{
35 		static const int NOT_SIGNALED = 0;
36 		static const int SIGNALED = 1;
37 
38 		::MW_CRITICAL_SECTION criticalSection;
39 		::MW_CONDITION_VARIABLE condition;
40 
41 		EventReset::Type resetType;
42 
43 		volatile uint32 numOfWaitingThreads;
44 		volatile int32 value;
45 		volatile bool isInitialized;
46 
47 	private:
48 
AutoResetIfNeed()49 		void AutoResetIfNeed()
50 		{
51 			if (resetType == EventReset::MANUAL)
52 			{
53 				return;
54 			}
55 			value = NOT_SIGNALED;
56 		}
57 
58 
59 	public:
60 
61 		MT_NOCOPYABLE(Event);
62 
Event()63 		Event()
64 			: numOfWaitingThreads(0)
65 			, isInitialized(false)
66 		{
67 		}
68 
Event(EventReset::Type resetType_,bool initialState)69 		Event(EventReset::Type resetType_, bool initialState)
70 			: numOfWaitingThreads(0)
71 			, isInitialized(false)
72 		{
73 			Create(resetType_, initialState);
74 		}
75 
~Event()76 		~Event()
77 		{
78 			if (isInitialized)
79 			{
80 				::DeleteCriticalSection(&criticalSection);
81 				isInitialized = false;
82 			}
83 		}
84 
Create(EventReset::Type resetType_,bool initialState)85 		void Create(EventReset::Type resetType_, bool initialState)
86 		{
87 			MT_ASSERT (!isInitialized, "Event already initialized");
88 			resetType = resetType_;
89 
90 			::InitializeCriticalSectionAndSpinCount( &criticalSection, 16 );
91 			::InitializeConditionVariable( &condition );
92 
93 			value = initialState ? SIGNALED : NOT_SIGNALED;
94 			isInitialized = true;
95 			numOfWaitingThreads = 0;
96 		}
97 
Signal()98 		void Signal()
99 		{
100 			MT_ASSERT (isInitialized, "Event not initialized");
101 			::EnterCriticalSection( &criticalSection );
102 			value = SIGNALED;
103 			if (numOfWaitingThreads > 0)
104 			{
105 				if (resetType == EventReset::MANUAL)
106 				{
107 					::WakeAllConditionVariable( &condition );
108 				} else
109 				{
110 					::WakeConditionVariable( &condition );
111 				}
112 			}
113 			::LeaveCriticalSection( &criticalSection );
114 		}
115 
Reset()116 		void Reset()
117 		{
118 			MT_ASSERT (isInitialized, "Event not initialized");
119 			MT_ASSERT(resetType == EventReset::MANUAL, "Can't reset, auto reset event");
120 
121 			::EnterCriticalSection( &criticalSection );
122 			value = NOT_SIGNALED;
123 			::LeaveCriticalSection( &criticalSection );
124 		}
125 
Wait(uint32 milliseconds)126 		bool Wait(uint32 milliseconds)
127 		{
128 			MT_ASSERT (isInitialized, "Event not initialized");
129 
130 			::EnterCriticalSection( &criticalSection );
131 			// early exit if event already signaled
132 			if ( value != NOT_SIGNALED )
133 			{
134 				AutoResetIfNeed();
135 				::LeaveCriticalSection( &criticalSection );
136 				return true;
137 			}
138 
139 			numOfWaitingThreads++;
140 
141 			for(;;)
142 			{
143 				MW_BOOL ret = ::SleepConditionVariableCS(&condition, &criticalSection, (MW_DWORD)milliseconds);
144 
145 #if defined(MT_DEBUG) || defined(MT_INSTRUMENTED_BUILD)
146 				if (ret == 0)
147 				{
148 						MW_DWORD err = ::GetLastError();
149 						MT_USED_IN_ASSERT(err);
150 						MT_ASSERT(err == MW_ERROR_TIMEOUT, "Unexpected return value from SleepConditionVariable");
151 				}
152 #endif
153 
154 				/*
155 					https://msdn.microsoft.com/en-us/library/windows/desktop/ms686301(v=vs.85).aspx
156 
157 					Condition variables are subject to spurious wakeups (those not associated with an explicit wake) and stolen wakeups (another thread manages to run before the woken thread).
158 					Therefore, you should recheck a predicate (typically in a while loop) after a sleep operation returns.
159 				*/
160 				if (value == SIGNALED || ret == 0)
161 				{
162 					break;
163 				}
164 			}
165 
166 			numOfWaitingThreads--;
167 			bool isSignaled = (value != NOT_SIGNALED);
168 			if (isSignaled)
169 			{
170 				AutoResetIfNeed();
171 			}
172 
173 			::LeaveCriticalSection( &criticalSection );
174 			return isSignaled;
175 		}
176 
177 	};
178 
179 }
180 
181 
182 #endif
183