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// @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
// Macro to get line as a string constant
#define MONGO_STRINGIFY(X) #X
// Double-expansion trick to get preproc to actually substitute __LINE__
#define _MONGO_LINE_STRING(LINE) MONGO_STRINGIFY( LINE )
#define MONGO_LINE_STRING _MONGO_LINE_STRING( __LINE__ )
// Mutex names should be as <file>::<line> string
#define MONGO_FILE_LINE __FILE__ "::" MONGO_LINE_STRING
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;
};
}
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