1#ifndef _DESEMAPHORE_HPP
2#define _DESEMAPHORE_HPP
3/*-------------------------------------------------------------------------
4 * drawElements C++ Base Library
5 * -----------------------------
6 *
7 * Copyright 2014 The Android Open Source Project
8 *
9 * Licensed under the Apache License, Version 2.0 (the "License");
10 * you may not use this file except in compliance with the License.
11 * You may obtain a copy of the License at
12 *
13 *      http://www.apache.org/licenses/LICENSE-2.0
14 *
15 * Unless required by applicable law or agreed to in writing, software
16 * distributed under the License is distributed on an "AS IS" BASIS,
17 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
18 * See the License for the specific language governing permissions and
19 * limitations under the License.
20 *
21 *//*!
22 * \file
23 * \brief deSemaphore C++ wrapper.
24 *//*--------------------------------------------------------------------*/
25
26#include "deDefs.hpp"
27#include "deSemaphore.h"
28
29namespace de
30{
31
32/*--------------------------------------------------------------------*//*!
33 * \brief Semaphore
34 *
35 * Semaphore provides standard semaphore functionality.
36 *
37 * Semaphore is thread-safe counter that can be used to control access
38 * to a set of resources. The count can be incremented and decremented.
39 * When decrementing causes counter to reach negative value, it will
40 * block until increment has been called from an another thread.
41 *//*--------------------------------------------------------------------*/
42class Semaphore
43{
44public:
45					Semaphore		(int initialValue, deUint32 flags = 0);
46					~Semaphore		(void);
47
48	void			increment		(void) throw();
49	void			decrement		(void) throw();
50	bool			tryDecrement	(void) throw();
51
52private:
53					Semaphore		(const Semaphore& other); // Not allowed!
54	Semaphore&		operator=		(const Semaphore& other); // Not allowed!
55
56	deSemaphore		m_semaphore;
57};
58
59// Inline implementations.
60
61/*--------------------------------------------------------------------*//*!
62 * \brief Increment semaphore count.
63 *
64 * Incremeting increases semaphore value by 1. If a value is currently
65 * negative (there is a thread waiting in decrement) the waiting thread
66 * will be resumed.
67 *
68 * Incrementing semaphore will never block.
69 *//*--------------------------------------------------------------------*/
70inline void Semaphore::increment (void) throw()
71{
72	deSemaphore_increment(m_semaphore);
73}
74
75/*--------------------------------------------------------------------*//*!
76 * \brief Decrement semaphore count.
77 *
78 * Decrementing decreases semaphore value by 1. If resulting value is negative
79 * (only -1 is possible) decrement() will block until the value is again 0
80 * (increment() has been called).
81 *
82 * If there is an another thread waiting in decrement(), the current thread
83 * will block until other thread(s) have been resumed.
84 *//*--------------------------------------------------------------------*/
85inline void Semaphore::decrement (void) throw()
86{
87	deSemaphore_decrement(m_semaphore);
88}
89
90/*--------------------------------------------------------------------*//*!
91 * \brief Try to decrement semaphore value.
92 * \return true if decrementing was successful without blocking, false
93 *		   otherwise
94 *
95 * This function will never block, i.e. it will return false if decrementing
96 * semaphore counter would result in negative value or there is already
97 * one or more threads waiting for this semaphore.
98 *//*--------------------------------------------------------------------*/
99inline bool Semaphore::tryDecrement (void) throw()
100{
101	return deSemaphore_tryDecrement(m_semaphore) == DE_TRUE;
102}
103
104} // de
105
106#endif // _DESEMAPHORE_HPP
107