src/util/pthread_glock.c

   1 /*
   2  * Copyright 2000, International Business Machines Corporation and others.
   3  * All Rights Reserved.
   4  *
   5  * This software has been released under the terms of the IBM Public
   6  * License.  For details, see the LICENSE file in the top-level source
   7  * directory or online at http://www.openafs.org/dl/license10.html
   8  */
   9
  10 #include <afsconfig.h>
  11 #include <afs/param.h>
  12
  13 RCSID
  14     ("$Header$");
  15
  16 #if defined(AFS_NT40_ENV) && defined(AFS_PTHREAD_ENV)
  17 #define AFS_GRMUTEX_DECLSPEC __declspec(dllexport)
  18 #endif
  19 #include <afs/pthread_glock.h>
  20 #include <string.h>
  21
  22 /*
  23  * Implement a pthread based recursive global lock for use in porting
  24  * old lwp style code to pthreads.
  25  */
  26
  27 pthread_recursive_mutex_t grmutex;
  28
  29 static int glock_init = 0;
  30 static pthread_once_t glock_init_once = PTHREAD_ONCE_INIT;
  31
  32 static void
  33 glock_init_func(void)
  34 {
  35     pthread_mutex_init(&grmutex.mut, (const pthread_mutexattr_t *)0);
  36     grmutex.times_inside = 0;
  37     grmutex.owner = (pthread_t) 0;
  38     grmutex.locked = 0;
  39     glock_init = 1;
  40 }
  41
  42 int
  43 pthread_recursive_mutex_lock(pthread_recursive_mutex_t * mut)
  44 {
  45     int rc = 0;
  46
  47 /*
  48  *    FSLog("Entered pthread_recursive_mutex_lock, thread id is %d\n",
  49  *              pthread_self());
  50  */
  51
  52     (glock_init || pthread_once(&glock_init_once, glock_init_func));
  53
  54     if (mut->locked) {
  55         if (pthread_equal(mut->owner, pthread_self())) {
  56             mut->times_inside++;
  57             return rc;
  58         }
  59     }
  60     rc = pthread_mutex_lock(&mut->mut);
  61     if (rc == 0) {
  62         mut->times_inside = 1;
  63         mut->owner = pthread_self();
  64         mut->locked = 1;
  65     }
  66
  67     return rc;
  68 }
  69
  70 int
  71 pthread_recursive_mutex_unlock(pthread_recursive_mutex_t * mut)
  72 {
  73     int rc = 0;
  74
  75 /*
  76  *    FSLog("Entered pthread_recursive_mutex_unlock, thread id is %d\n",
  77  *              pthread_self());
  78  *
  79  */
  80
  81     (glock_init || pthread_once(&glock_init_once, glock_init_func));
  82
  83     if ((mut->locked) && (pthread_equal(mut->owner, pthread_self()))) {
  84         mut->times_inside--;
  85         if (mut->times_inside == 0) {
  86             mut->locked = 0;
  87             rc = pthread_mutex_unlock(&mut->mut);
  88         }
  89     } else {
  90         /*
  91          * Note that you might want to try to differentiate between
  92          * the two possible reasons you're here, but since we don't
  93          * hold the mutex, it's useless to try.
  94          */
  95         rc = -1;
  96     }
  97     return rc;
  98 }