blob: ef0b47d95ae507b15dee1e2a1bf14ff74f89b931 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
|
//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2005-2011. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/libs/interprocess for documentation.
//
//////////////////////////////////////////////////////////////////////////////
#ifndef BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP
#define BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP
#if (defined _MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif
#include <boost/interprocess/detail/config_begin.hpp>
#include <boost/interprocess/detail/workaround.hpp>
#include <boost/interprocess/detail/posix_time_types_wrk.hpp>
#include <boost/assert.hpp>
#include <boost/interprocess/detail/atomic.hpp>
#include <boost/cstdint.hpp>
#include <boost/interprocess/detail/os_thread_functions.hpp>
namespace boost {
namespace interprocess {
namespace ipcdetail {
class spin_mutex
{
spin_mutex(const spin_mutex &);
spin_mutex &operator=(const spin_mutex &);
public:
spin_mutex();
~spin_mutex();
void lock();
bool try_lock();
bool timed_lock(const boost::posix_time::ptime &abs_time);
void unlock();
void take_ownership(){};
private:
volatile boost::uint32_t m_s;
};
inline spin_mutex::spin_mutex()
: m_s(0)
{
//Note that this class is initialized to zero.
//So zeroed memory can be interpreted as an
//initialized mutex
}
inline spin_mutex::~spin_mutex()
{
//Trivial destructor
}
inline void spin_mutex::lock(void)
{
do{
boost::uint32_t prev_s = ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 1, 0);
if (m_s == 1 && prev_s == 0){
break;
}
// relinquish current timeslice
ipcdetail::thread_yield();
}while (true);
}
inline bool spin_mutex::try_lock(void)
{
boost::uint32_t prev_s = ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 1, 0);
return m_s == 1 && prev_s == 0;
}
inline bool spin_mutex::timed_lock(const boost::posix_time::ptime &abs_time)
{
if(abs_time == boost::posix_time::pos_infin){
this->lock();
return true;
}
//Obtain current count and target time
boost::posix_time::ptime now = microsec_clock::universal_time();
do{
if(this->try_lock()){
break;
}
now = microsec_clock::universal_time();
if(now >= abs_time){
return false;
}
// relinquish current time slice
ipcdetail::thread_yield();
}while (true);
return true;
}
inline void spin_mutex::unlock(void)
{ ipcdetail::atomic_cas32(const_cast<boost::uint32_t*>(&m_s), 0, 1); }
} //namespace ipcdetail {
} //namespace interprocess {
} //namespace boost {
#include <boost/interprocess/detail/config_end.hpp>
#endif //BOOST_INTERPROCESS_DETAIL_SPIN_MUTEX_HPP
|
