Skip to content
This repository

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
tree: 11513316d1
Fetching contributors…

Octocat-spinner-32-eaf2f5

Cannot retrieve contributors at this time

file 203 lines (183 sloc) 6.464 kb
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202
// @file mutex.h

/* Copyright 2009 10gen Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

#pragma once

#ifdef _WIN32
#include "mongo/platform/windows_basic.h"
#endif

#include <boost/noncopyable.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/thread/xtime.hpp>

#include "mongo/util/assert_util.h"
#include "mongo/util/heapcheck.h"
#include "mongo/util/concurrency/threadlocal.h"
#include "mongo/util/time_support.h"

#if defined(_DEBUG)
#include "mongo/util/concurrency/mutexdebugger.h"
#endif

namespace mongo {

    inline boost::xtime incxtimemillis( long long s ) {
        boost::xtime xt;
        boost::xtime_get(&xt, MONGO_BOOST_TIME_UTC);
        xt.sec += (int)( s / 1000 );
        xt.nsec += (int)(( s % 1000 ) * 1000000);
        if ( xt.nsec >= 1000000000 ) {
            xt.nsec -= 1000000000;
            xt.sec++;
        }
        return xt;
    }

    // If you create a local static instance of this class, that instance will be destroyed
    // before all global static objects are destroyed, so _destroyingStatics will be set
    // to true before the global static variables are destroyed.
    class StaticObserver : boost::noncopyable {
    public:
        static bool _destroyingStatics;
        ~StaticObserver() { _destroyingStatics = true; }
    };

    /** On pthread systems, it is an error to destroy a mutex while held (boost mutex
* may use pthread). Static global mutexes may be held upon shutdown in our
* implementation, and this way we avoid destroying them.
* NOT recursive.
*/
    class mutex : boost::noncopyable {
    public:
        const char * const _name;
        mutex(const char *name) : _name(name)
        {
            _m = new boost::timed_mutex();
            IGNORE_OBJECT( _m ); // Turn-off heap checking on _m
        }
        ~mutex() {
            if( !StaticObserver::_destroyingStatics ) {
                UNIGNORE_OBJECT( _m );
                delete _m;
            }
        }

        class try_lock : boost::noncopyable {
        public:
            try_lock( mongo::mutex &m , int millis = 0 )
                : _l( m.boost() , incxtimemillis( millis ) ) ,
                  ok( _l.owns_lock() )
            { }
        private:
            boost::timed_mutex::scoped_timed_lock _l;
        public:
            const bool ok;
        };

        class scoped_lock : boost::noncopyable {
        public:
#if defined(_DEBUG)
            struct PostStaticCheck {
                PostStaticCheck();
            } _check;
            mongo::mutex * const _mut;
#endif
            scoped_lock( mongo::mutex &m ) :
#if defined(_DEBUG)
            _mut(&m),
#endif
            _l( m.boost() ) {
#if defined(_DEBUG)
                mutexDebugger.entering(_mut->_name);
#endif
            }
            ~scoped_lock() {
#if defined(_DEBUG)
                mutexDebugger.leaving(_mut->_name);
#endif
            }
            boost::timed_mutex::scoped_lock &boost() { return _l; }
        private:
            boost::timed_mutex::scoped_lock _l;
        };
    private:
        boost::timed_mutex &boost() { return *_m; }
        boost::timed_mutex *_m;
    };

    typedef mongo::mutex::scoped_lock scoped_lock;

    /** The concept with SimpleMutex is that it is a basic lock/unlock with no
special functionality (such as try and try timeout). Thus it can be
implemented using OS-specific facilities in all environments (if desired).
On Windows, the implementation below is faster than boost mutex.
*/
#if defined(_WIN32)
    class SimpleMutex : boost::noncopyable {
    public:
        SimpleMutex( const char * ) { InitializeCriticalSection( &_cs ); }
        void dassertLocked() const { }
        void lock() { EnterCriticalSection( &_cs ); }
        void unlock() { LeaveCriticalSection( &_cs ); }
        class scoped_lock {
            SimpleMutex& _m;
        public:
            scoped_lock( SimpleMutex &m ) : _m(m) { _m.lock(); }
            ~scoped_lock() { _m.unlock(); }
            const SimpleMutex& m() const { return _m; }
        };

    private:
        CRITICAL_SECTION _cs;
    };
#else
    class SimpleMutex : boost::noncopyable {
    public:
        void dassertLocked() const { }
        SimpleMutex(const char* name) { verify( pthread_mutex_init(&_lock,0) == 0 ); }
        ~SimpleMutex(){
            if ( ! StaticObserver::_destroyingStatics ) {
                verify( pthread_mutex_destroy(&_lock) == 0 );
            }
        }

        void lock() { verify( pthread_mutex_lock(&_lock) == 0 ); }
        void unlock() { verify( pthread_mutex_unlock(&_lock) == 0 ); }
    public:
        class scoped_lock : boost::noncopyable {
            SimpleMutex& _m;
        public:
            scoped_lock( SimpleMutex &m ) : _m(m) { _m.lock(); }
            ~scoped_lock() { _m.unlock(); }
            const SimpleMutex& m() const { return _m; }
        };

    private:
        pthread_mutex_t _lock;
    };
#endif

    /** This can be used instead of boost recursive mutex. The advantage is the _DEBUG checks
* and ability to assertLocked(). This has not yet been tested for speed vs. the boost one.
*/
    class RecursiveMutex : boost::noncopyable {
    public:
        RecursiveMutex(const char* name) : m(name) { }
        bool isLocked() const { return n.get() > 0; }
        class scoped_lock : boost::noncopyable {
            RecursiveMutex& rm;
            int& nLocksByMe;
        public:
            scoped_lock( RecursiveMutex &m ) : rm(m), nLocksByMe(rm.n.getRef()) {
                if( nLocksByMe++ == 0 )
                    rm.m.lock();
            }
            ~scoped_lock() {
                verify( nLocksByMe > 0 );
                if( --nLocksByMe == 0 ) {
                    rm.m.unlock();
                }
            }
        };
    private:
        SimpleMutex m;
        ThreadLocalValue<int> n;
    };

}
Something went wrong with that request. Please try again.