snmplib/mt_support.c

/* mt_support.c - multi-thread resource locking support */
/*
 * Author: Markku Laukkanen
 * Created: 6-Sep-1999
 * History:
 *  8-Sep-1999 M. Slifcak method names changed;
 *                        use array of resource locking structures.
 */

#include <config.h>
#include <errno.h>
#include "mt_support.h"

#ifdef __cplusplus
extern "C" {
#endif

#ifdef _REENTRANT

static
mutex_type s_res[MT_MAX_IDS][MT_LIB_MAXIMUM];  /* locking structures */

static mutex_type * _mt_res(int groupID, int resourceID)
{
    if (groupID < 1) return 0;
    if (groupID >= MT_MAX_IDS) return 0;
    if (resourceID < 1) return 0;
    if (resourceID >= MT_LIB_MAXIMUM) return 0;
    return (&s_res[groupID][resourceID]);
}

static
int snmp_res_init_mutex(mutex_type * mutex)
{    
    int rc = 0;
#if HAVE_PTHREAD_H
    rc = pthread_mutex_init(mutex, MT_MUTEX_INIT_DEFAULT);
#elif defined(WIN32)
    InitializeCriticalSection(mutex);
#endif

    return rc;
}

int snmp_res_init(void)
{    
    int ii, jj;
    int rc = 0;
    mutex_type *mutex;

  for (jj = 0; (0 == rc) && (jj < MT_MAX_IDS); jj++)
  for (ii = 0; (0 == rc) && (ii < MT_LIB_MAXIMUM); ii++)
  {
    mutex = _mt_res(jj, ii);
    if (!mutex) continue;
    rc = snmp_res_init_mutex( mutex );
  }

    return rc;
}

int snmp_res_destroy_mutex(int groupID, int resourceID)
{    
    int rc = 0;
    mutex_type *mutex = _mt_res(groupID, resourceID);
    if (!mutex) return EFAULT;

#if HAVE_PTHREAD_H
    rc = pthread_mutex_destroy(mutex);
#elif defined(WIN32)
    DeleteCriticalSection(mutex);
#endif

    return rc;
}
    
int snmp_res_lock(int groupID, int resourceID)
{
    int rc = 0;
    mutex_type *mutex = _mt_res(groupID, resourceID);
    if (!mutex) return EFAULT;

#if HAVE_PTHREAD_H
    rc = pthread_mutex_lock(mutex);
#elif defined(WIN32)
    EnterCriticalSection(mutex);
#endif

    return rc;
}

int snmp_res_unlock(int groupID, int resourceID)
{
    int rc = 0;
    mutex_type *mutex = _mt_res(groupID, resourceID);
    if (!mutex) return EFAULT;

#if HAVE_PTHREAD_H
    rc = pthread_mutex_unlock(mutex);
#elif defined(WIN32)
    LeaveCriticalSection(mutex);
#endif

    return rc;
}


#else  /* !_REENTRANT */

#ifdef WIN32

/* Provide "do nothing" targets for Release (.DLL) builds. */
#undef snmp_res_init
#undef snmp_res_lock
#undef snmp_res_unlock
#undef snmp_res_destroy_mutex

int snmp_res_init(void) { return 0; }
int snmp_res_lock(int groupID, int resourceID) { return 0; }
int snmp_res_unlock(int groupID, int resourceID) { return 0; }
int snmp_res_destroy_mutex(int groupID, int resourceID) { return 0; }
#endif /* !WIN32 */

#endif /* !_REENTRANT */


#ifdef __cplusplus
};
#endif