// 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 "pch.h"
#include "rwlock.h"

namespace mongo {

    /**
     * The spinlock currently requires late GCC support routines to be efficient.
     * Other platforms default to a mutex implemenation.
     */
    class SpinLock {
    public:
        SpinLock();
        ~SpinLock();

        void lock();
        void unlock();

    private:
#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
        volatile bool _locked;
#elif defined(_WIN32)
        CRITICAL_SECTION _cs;
#else
        // default to a scoped mutex if not implemented
        RWLock _mutex;
#endif

        // Non-copyable, non-assignable
        SpinLock(SpinLock&);
        SpinLock& operator=(SpinLock&);
    };

}  // namespace mongo