summaryrefslogtreecommitdiff
path: root/src/atomic_ptr.hpp
blob: 54db64f554cf808787eeb61288e2d3004e0128ea (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
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
/*
    Copyright (c) 2007-2010 iMatix Corporation

    This file is part of 0MQ.

    0MQ is free software; you can redistribute it and/or modify it under
    the terms of the Lesser GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    0MQ is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    Lesser GNU General Public License for more details.

    You should have received a copy of the Lesser GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef __ZMQ_ATOMIC_PTR_HPP_INCLUDED__
#define __ZMQ_ATOMIC_PTR_HPP_INCLUDED__

#include "platform.hpp"

#if defined ZMQ_FORCE_MUTEXES
#define ZMQ_ATOMIC_PTR_MUTEX
#elif (defined __i386__ || defined __x86_64__) && defined __GNUC__
#define ZMQ_ATOMIC_PTR_X86
#elif defined ZMQ_HAVE_WINDOWS
#define ZMQ_ATOMIC_PTR_WINDOWS
#elif (defined ZMQ_HAVE_SOLARIS || defined ZMQ_HAVE_NETBSD)
#define ZMQ_ATOMIC_PTR_ATOMIC_H
#else
#define ZMQ_ATOMIC_PTR_MUTEX
#endif

#if defined ZMQ_ATOMIC_PTR_MUTEX
#include "mutex.hpp"
#elif defined ZMQ_ATOMIC_PTR_WINDOWS
#include "windows.hpp"
#elif defined ZMQ_ATOMIC_PTR_ATOMIC_H
#include <atomic.h>
#endif

namespace zmq
{

    //  This class encapsulates several atomic operations on pointers.

    template <typename T> class atomic_ptr_t
    {
    public:

        //  Initialise atomic pointer
        inline atomic_ptr_t ()
        {
            ptr = NULL;
        }

        //  Destroy atomic pointer
        inline ~atomic_ptr_t ()
        {
        }

        //  Set value of atomic pointer in a non-threadsafe way
        //  Use this function only when you are sure that at most one
        //  thread is accessing the pointer at the moment.
        inline void set (T *ptr_)
        {
            this->ptr = ptr_;
        }

        //  Perform atomic 'exchange pointers' operation. Pointer is set
        //  to the 'val' value. Old value is returned.
        inline T *xchg (T *val_)
        {
#if defined ZMQ_ATOMIC_PTR_WINDOWS
            return (T*) InterlockedExchangePointer ((PVOID*) &ptr, val_);
#elif defined ZMQ_ATOMIC_PTR_ATOMIC_H
            return (T*) atomic_swap_ptr (&ptr, val_);
#elif defined ZMQ_ATOMIC_PTR_X86
            T *old;
            __asm__ volatile (
                "lock; xchg %0, %2"
                : "=r" (old), "=m" (ptr)
                : "m" (ptr), "0" (val_));
            return old;
#elif defined ZMQ_ATOMIC_PTR_MUTEX
            sync.lock ();
            T *old = (T*) ptr;
            ptr = val_;
            sync.unlock ();
            return old;
#else
#error atomic_ptr is not implemented for this platform
#endif
        }

        //  Perform atomic 'compare and swap' operation on the pointer.
        //  The pointer is compared to 'cmp' argument and if they are
        //  equal, its value is set to 'val'. Old value of the pointer
        //  is returned.
        inline T *cas (T *cmp_, T *val_)
        {
#if defined ZMQ_ATOMIC_PTR_WINDOWS
            return (T*) InterlockedCompareExchangePointer (
                (volatile PVOID*) &ptr, val_, cmp_);
#elif defined ZMQ_ATOMIC_PTR_ATOMIC_H
            return (T*) atomic_cas_ptr (&ptr, cmp_, val_);
#elif defined ZMQ_ATOMIC_PTR_X86
            T *old;
            __asm__ volatile (
                "lock; cmpxchg %2, %3"
                : "=a" (old), "=m" (ptr)
                : "r" (val_), "m" (ptr), "0" (cmp_)
                : "cc");
            return old;
#elif defined ZMQ_ATOMIC_PTR_MUTEX
            sync.lock ();
            T *old = (T*) ptr;
            if (ptr == cmp_)
                ptr = val_;
            sync.unlock ();
            return old;
#else
#error atomic_ptr is not implemented for this platform
#endif
        }

    private:

        volatile T *ptr;
#if defined ZMQ_ATOMIC_PTR_MUTEX
        mutex_t sync;
#endif

        atomic_ptr_t (const atomic_ptr_t&);
        void operator = (const atomic_ptr_t&);
    };

}

//  Remove macros local to this file.
#if defined ZMQ_ATOMIC_PTR_WINDOWS
#undef ZMQ_ATOMIC_PTR_WINDOWS
#endif
#if defined ZMQ_ATOMIC_PTR_ATOMIC_H
#undef ZMQ_ATOMIC_PTR_ATOMIC_H
#endif
#if defined ZMQ_ATOMIC_PTR_X86
#undef ZMQ_ATOMIC_PTR_X86
#endif
#if defined ZMQ_ATOMIC_PTR_MUTEX
#undef ZMQ_ATOMIC_PTR_MUTEX
#endif

#endif