root/trunk/dep/src/zthread/linux/AtomicFastLock.h @ 245

Revision 2, 2.6 kB (checked in by yumileroy, 17 years ago)

[svn] * Proper SVN structure

Original author: Neo2003
Date: 2008-10-02 16:23:55-05:00
Line 
1/*
2 * Copyright (c) 2005, Eric Crahen
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a copy
5 * of this software and associated documentation files (the "Software"), to deal
6 * in the Software without restriction, including without limitation the rights
7 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8 * copies of the Software, and to permit persons to whom the Software is furnished
9 * to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included in all
12 * copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
18 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
19 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
20 *
21 */
22
23#ifndef __ZTFASTLOCK_H__
24#define __ZTFASTLOCK_H__
25
26#include "zthread/NonCopyable.h"
27#include "../ThreadOps.h"
28#include <assert.h>
29#include <asm/atomic.h>
30
31#if !defined(NDEBUG)
32#  include <pthread.h>
33#endif
34
35namespace ZThread {
36
37/**
38 * @class FastLock
39 *
40 * @author Eric Crahen <http://www.code-foo.com>
41 * @date <2003-07-16T23:27:03-0400>
42 * @version 2.2.0
43 *
44 * This implementation of a FastLock uses the atomic operations that
45 * linux provides with its kernel sources. This demonstrates how to implement
46 * a spinlock with a decrement and test primative.
47 */ 
48class FastLock : private NonCopyable {
49 
50  atomic_t _value;
51 
52#if !defined(NDEBUG)
53  pthread_t _owner;
54#endif
55
56public:
57 
58  inline FastLock() {
59 
60    atomic_t tmp =  ATOMIC_INIT(1);
61    _value = tmp;
62
63  }
64 
65  inline ~FastLock() {
66
67    assert(atomic_read(&_value) == 1);
68    assert(_owner == 0);
69
70  }
71 
72  inline void acquire() {
73
74    while(!atomic_dec_and_test(&_value)) {
75
76      atomic_inc(&_value);
77      ThreadOps::yield();
78
79    }
80       
81#if !defined(NDEBUG)
82    _owner = pthread_self();
83#endif
84  }
85
86  inline void release() {
87   
88#if !defined(NDEBUG)
89    assert(pthread_equal(_owner, pthread_self()) != 0);
90#endif
91
92    atomic_inc(&_value);
93    _owner = 0;
94
95  }
96 
97  inline bool tryAcquire(unsigned long timeout=0) {
98   
99    bool wasLocked = atomic_dec_and_test(&_value);
100    if(!wasLocked)
101      atomic_inc(&_value);
102
103#if !defined(NDEBUG)
104    if(wasLocked)
105      _owner = pthread_self();
106#endif
107
108    return wasLocked;
109   
110  }
111 
112}; /* FastLock */
113
114
115} // namespace ZThread
116
117#endif
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