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 #include <roken.h>
  14
  15 #if defined(AFS_NT40_ENV) && defined(AFS_PTHREAD_ENV)
  16 #define AFS_GRMUTEX_DECLSPEC __declspec(dllexport)
  17 #endif
  18 #ifdef AFS_PTHREAD_ENV
  19 #include <afs/pthread_glock.h>
  20
  21 /*
  22  * Implement a pthread based recursive global lock for use in porting
  23  * old lwp style code to pthreads.
  24  */
  25
  26 pthread_recursive_mutex_t grmutex;
  27
  28 static int glock_init = 0;
  29 static pthread_once_t glock_init_once = PTHREAD_ONCE_INIT;
  30
  31 static void
  32 glock_init_func(void)
  33 {
  34     pthread_mutex_init(&grmutex.mut, (const pthread_mutexattr_t *)0);
  35     grmutex.times_inside = 0;
  36     grmutex.owner = (pthread_t) 0;
  37     grmutex.locked = 0;
  38     glock_init = 1;
  39 }
  40
  41 int
  42 pthread_recursive_mutex_lock(pthread_recursive_mutex_t * mut)
  43 {
  44     int rc = 0;
  45
  46     if (!glock_init)
  47         pthread_once(&glock_init_once, glock_init_func);
  48
  49     if (mut->locked) {
  50         if (pthread_equal(mut->owner, pthread_self())) {
  51             mut->times_inside++;
  52             return rc;
  53         }
  54     }
  55     rc = pthread_mutex_lock(&mut->mut);
  56     if (rc == 0) {
  57         mut->times_inside = 1;
  58         mut->owner = pthread_self();
  59         mut->locked = 1;
  60     }
  61
  62     return rc;
  63 }
  64
  65 int
  66 pthread_recursive_mutex_unlock(pthread_recursive_mutex_t * mut)
  67 {
  68     int rc = 0;
  69
  70     if (!glock_init)
  71         pthread_once(&glock_init_once, glock_init_func);
  72
  73     if ((mut->locked) && (pthread_equal(mut->owner, pthread_self()))) {
  74         mut->times_inside--;
  75         if (mut->times_inside == 0) {
  76             mut->locked = 0;
  77             rc = pthread_mutex_unlock(&mut->mut);
  78         }
  79     } else {
  80         /*
  81          * Note that you might want to try to differentiate between
  82          * the two possible reasons you're here, but since we don't
  83          * hold the mutex, it's useless to try.
  84          */
  85         rc = -1;
  86     }
  87     return rc;
  88 }
  89 #endif