win_mutex.c

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/* FreeTDS - Library of routines accessing Sybase and Microsoft databases
 * Copyright (C) 2010  Frediano Ziglio
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */
 
#include <config.h>
 
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif /* HAVE_STDLIB_H */
 
#ifdef _WIN32
 
#if HAVE_STRING_H
#include <string.h>
#endif /* HAVE_STRING_H */
 
#include <freetds/windows.h>
#include <freetds/thread.h>
 
#include "ptw32_MCS_lock.c"
 
void
tds_win_mutex_lock(tds_raw_mutex * mutex)
{
    if (!InterlockedExchangeAdd(&mutex->done, 0)) { /* MBR fence */
        ptw32_mcs_local_node_t node;
 
        ptw32_mcs_lock_acquire(&mutex->lock, &node);
        if (!mutex->done) {
            InitializeCriticalSection(&mutex->crit);
            mutex->done = 1;
        }
        ptw32_mcs_lock_release(&node);
    }
    EnterCriticalSection(&mutex->crit);
    mutex->thread_id = GetCurrentThreadId();
}
 
int
tds_raw_mutex_trylock(tds_raw_mutex * mutex)
{
    if (!mutex->done && !InterlockedExchangeAdd(&mutex->done, 0)) { /* MBR fence */
        ptw32_mcs_local_node_t node;
 
        ptw32_mcs_lock_acquire(&mutex->lock, &node);
        if (!mutex->done) {
            InitializeCriticalSection(&mutex->crit);
            mutex->done = 1;
        }
        ptw32_mcs_lock_release(&node);
    }
    if (TryEnterCriticalSection(&mutex->crit)) {
        DWORD thread_id = GetCurrentThreadId();
        if (mutex->thread_id == thread_id) {
            LeaveCriticalSection(&mutex->crit);
            return -1;
        }
        mutex->thread_id = thread_id;
        return 0;
    }
    return -1;
}
 
#endif