summaryrefslogtreecommitdiff
path: root/src/mongo/util/concurrency/threadlocal.h
blob: 387b3697545a8ba5f2c051e9406237991d77af6b (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
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
#pragma once

/**
*    Copyright (C) 2011 10gen Inc.
*
*    This program is free software: you can redistribute it and/or  modify
*    it under the terms of the GNU Affero General Public License, version 3,
*    as published by the Free Software Foundation.
*
*    This program 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
*    GNU Affero General Public License for more details.
*
*    You should have received a copy of the GNU Affero General Public License
*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*
*    As a special exception, the copyright holders give permission to link the
*    code of portions of this program with the OpenSSL library under certain
*    conditions as described in each individual source file and distribute
*    linked combinations including the program with the OpenSSL library. You
*    must comply with the GNU Affero General Public License in all respects
*    for all of the code used other than as permitted herein. If you modify
*    file(s) with this exception, you may extend this exception to your
*    version of the file(s), but you are not obligated to do so. If you do not
*    wish to do so, delete this exception statement from your version. If you
*    delete this exception statement from all source files in the program,
*    then also delete it in the license file.
*/

#include <boost/thread/tss.hpp>

namespace mongo { 

    using boost::thread_specific_ptr;

    /* thread local "value" rather than a pointer
       good for things which have copy constructors (and the copy constructor is fast enough)
       e.g.
         ThreadLocalValue<int> myint;
    */
    template<class T>
    class ThreadLocalValue {
    public:
        ThreadLocalValue( T def = 0 ) : _default( def ) { }

        T get() const {
            T * val = _val.get();
            if ( val )
                return *val;
            return _default;
        }

        void set( const T& i ) {
            T *v = _val.get();
            if( v ) {
                *v = i;
                return;
            }
            v = new T(i);
            _val.reset( v );
        }

        T& getRef() {
            T *v = _val.get();
            if( v ) {
                return *v; 
            }
            v = new T(_default);
            _val.reset( v );
            return *v;
        }

    private:
        boost::thread_specific_ptr<T> _val;
        const T _default;
    };

    /* TSP
       These macros use intrinsics which are faster than boost::thread_specific_ptr. 
       However the intrinsics don't free up objects on thread closure. Thus we use 
       a combination here, with the assumption that reset's are infrequent, so that 
       get's are fast.
    */
#if defined(MONGO_HAVE___THREAD) || defined(MONGO_HAVE___DECLSPEC_THREAD)
        
    template< class T >
    struct TSP {
        boost::thread_specific_ptr<T> tsp;
    public:
        T* get() const;
        void reset(T* v);
        T* getMake() { 
            T *t = get();
            if( t == 0 )
                reset( t = new T() );
            return t;
        }
    };

# if defined(MONGO_HAVE___DECLSPEC_THREAD)

#  define TSP_DECLARE(T,p) extern TSP<T> p;

#  define TSP_DEFINE(T,p) __declspec( thread ) T* _ ## p; \
    TSP<T> p; \
    template<> T* TSP<T>::get() const { return _ ## p; } \
    void TSP<T>::reset(T* v) { \
        tsp.reset(v); \
        _ ## p = v; \
    } 
# else

#  define TSP_DECLARE(T,p) \
    extern __thread T* _ ## p; \
    template<> inline T* TSP<T>::get() const { return _ ## p; }	\
    extern TSP<T> p;

#  define TSP_DEFINE(T,p) \
    __thread T* _ ## p; \
    template<> void TSP<T>::reset(T* v) { \
        tsp.reset(v); \
        _ ## p = v; \
    } \
    TSP<T> p;
# endif

#elif defined(_POSIX_THREADS) && (_POSIX_THREADS >= 0)
    template< class T>
    struct TSP {
        pthread_key_t _key;
    public:
        TSP() {
            verify( pthread_key_create( &_key, TSP::dodelete ) == 0 );
        }

        ~TSP() {
            pthread_key_delete( _key );
        }

        static void dodelete( void* x ) {
            T* t = reinterpret_cast<T*>(x);
            delete t;
        }
        
        T* get() const { 
            return reinterpret_cast<T*>( pthread_getspecific( _key ) ); 
        }
        
        void reset(T* v) { 
            T* old = get();
            delete old;
            verify( pthread_setspecific( _key, v ) == 0 ); 
        }

        T* getMake() { 
            T *t = get();
            if( t == 0 ) {
                t = new T();
                reset( t );
            }
            return t;
        }
    };

#  define TSP_DECLARE(T,p) extern TSP<T> p;

#  define TSP_DEFINE(T,p) TSP<T> p; 

#else

    template< class T >
    struct TSP {
        thread_specific_ptr<T> tsp;
    public:
        T* get() const { return tsp.get(); }
        void reset(T* v) { tsp.reset(v); }
        T* getMake() { 
            T *t = get();
            if( t == 0 )
                reset( t = new T() );
            return t;
        }
    };

#  define TSP_DECLARE(T,p) extern TSP<T> p;

# define TSP_DEFINE(T,p) TSP<T> p; 

#endif

}