// @file mutex.h


/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    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
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    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 Server Side 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.
 */

#pragma once

#ifdef _WIN32
#include "mongo/platform/windows_basic.h"
#else
#include <pthread.h>
#endif

#include "mongo/base/disallow_copying.h"
#include "mongo/util/assert_util.h"

namespace mongo {

/** 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 {
    MONGO_DISALLOW_COPYING(SimpleMutex);

public:
    SimpleMutex() {
        InitializeCriticalSection(&_cs);
    }

    ~SimpleMutex() {
        DeleteCriticalSection(&_cs);
    }

    void lock() {
        EnterCriticalSection(&_cs);
    }
    void unlock() {
        LeaveCriticalSection(&_cs);
    }

private:
    CRITICAL_SECTION _cs;
};

#else

class SimpleMutex {
    MONGO_DISALLOW_COPYING(SimpleMutex);

public:
    SimpleMutex() {
        verify(pthread_mutex_init(&_lock, 0) == 0);
    }

    ~SimpleMutex() {
        verify(pthread_mutex_destroy(&_lock) == 0);
    }

    void lock() {
        verify(pthread_mutex_lock(&_lock) == 0);
    }

    void unlock() {
        verify(pthread_mutex_unlock(&_lock) == 0);
    }

private:
    pthread_mutex_t _lock;
};
#endif

}  // namespace mongo