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
29 namespace 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 *//*--------------------------------------------------------------------*/
42 class Semaphore
43 {
44 public:
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
52 private:
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 *//*--------------------------------------------------------------------*/
increment(void)70 inline 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 *//*--------------------------------------------------------------------*/
decrement(void)85 inline 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 *//*--------------------------------------------------------------------*/
tryDecrement(void)99 inline bool Semaphore::tryDecrement (void) throw()
100 {
101 return deSemaphore_tryDecrement(m_semaphore) == DE_TRUE;
102 }
103
104 } // de
105
106 #endif // _DESEMAPHORE_HPP
107