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// spin_lock.h
/**
* Copyright (C) 2008 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/>.
*/
#pragma once
#include "mutex.h"
namespace mongo {
/**
* The spinlock currently requires late GCC support routines to be efficient.
* Other platforms default to a mutex implemenation.
*/
class SpinLock : boost::noncopyable {
public:
SpinLock();
~SpinLock();
void lock();
void unlock();
static bool isfast(); // true if a real spinlock on this platform
private:
#if defined(_WIN32)
CRITICAL_SECTION _cs;
#elif defined(__USE_XOPEN2K)
pthread_spinlock_t _lock;
#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
volatile bool _locked;
#else
// default to a mutex if not implemented
SimpleMutex _mutex;
#endif
};
class scoped_spinlock : boost::noncopyable {
public:
scoped_spinlock( SpinLock& l ) : _l(l) {
_l.lock();
}
~scoped_spinlock() {
_l.unlock();}
private:
SpinLock& _l;
};
} // namespace mongo
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