lib/libthread_xu/thread/thr_cond.c

   1 /*
   2  * Copyright (c) 2005 David Xu <davidxu@freebsd.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice unmodified, this list of conditions, and the following
  10  *    disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  *
  26  * $DragonFly: src/lib/libthread_xu/thread/thr_cond.c,v 1.12 2008/04/15 01:45:22 dillon Exp $
  27  */
  28
  29 #include "namespace.h"
  30 #include <machine/tls.h>
  31
  32 #include <stdlib.h>
  33 #include <string.h>
  34 #include <pthread.h>
  35 #include <limits.h>
  36 #include "un-namespace.h"
  37
  38 #include "thr_private.h"
  39
  40 umtx_t          _cond_static_lock;
  41
  42 int     __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex);
  43 int     __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
  44                        const struct timespec *abstime);
  45 /*
  46  * Prototypes
  47  */
  48 static int cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr);
  49 static int cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
  50                     const struct timespec *abstime, int cancel);
  51 static int cond_signal_common(pthread_cond_t *cond, int broadcast);
  52
  53 static int
  54 cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
  55 {
  56         pthread_cond_t  pcond;
  57         int             rval = 0;
  58
  59         if ((pcond = (pthread_cond_t)
  60             malloc(sizeof(struct pthread_cond))) == NULL) {
  61                 rval = ENOMEM;
  62         } else {
  63                 /*
  64                  * Initialise the condition variable structure:
  65                  */
  66                 _thr_umtx_init(&pcond->c_lock);
  67                 pcond->c_seqno = 0;
  68                 pcond->c_waiters = 0;
  69                 pcond->c_broadcast = 0;
  70                 if (cond_attr == NULL || *cond_attr == NULL) {
  71                         pcond->c_pshared = 0;
  72                         pcond->c_clockid = CLOCK_REALTIME;
  73                 } else {
  74                         pcond->c_pshared = (*cond_attr)->c_pshared;
  75                         pcond->c_clockid = (*cond_attr)->c_clockid;
  76                 }
  77                 *cond = pcond;
  78         }
  79         /* Return the completion status: */
  80         return (rval);
  81 }
  82
  83 static int
  84 init_static(struct pthread *thread, pthread_cond_t *cond)
  85 {
  86         int ret;
  87
  88         THR_LOCK_ACQUIRE(thread, &_cond_static_lock);
  89
  90         if (*cond == NULL)
  91                 ret = cond_init(cond, NULL);
  92         else
  93                 ret = 0;
  94
  95         THR_LOCK_RELEASE(thread, &_cond_static_lock);
  96
  97         return (ret);
  98 }
  99
 100 int
 101 _pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
 102 {
 103         *cond = NULL;
 104         return cond_init(cond, cond_attr);
 105 }
 106
 107 int
 108 _pthread_cond_destroy(pthread_cond_t *cond)
 109 {
 110         struct pthread_cond     *cv;
 111         struct pthread          *curthread = tls_get_curthread();
 112         int                     rval = 0;
 113
 114         if (*cond == NULL)
 115                 rval = EINVAL;
 116         else {
 117                 /* Lock the condition variable structure: */
 118                 THR_LOCK_ACQUIRE(curthread, &(*cond)->c_lock);
 119                 if ((*cond)->c_waiters != 0) {
 120                         THR_LOCK_RELEASE(curthread, &(*cond)->c_lock);
 121                         return (EBUSY);
 122                 }
 123
 124                 /*
 125                  * NULL the caller's pointer now that the condition
 126                  * variable has been destroyed:
 127                  */
 128                 cv = *cond;
 129                 *cond = NULL;
 130
 131                 /* Unlock the condition variable structure: */
 132                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 133
 134                 /* Free the cond lock structure: */
 135
 136                 /*
 137                  * Free the memory allocated for the condition
 138                  * variable structure:
 139                  */
 140                 free(cv);
 141
 142         }
 143         /* Return the completion status: */
 144         return (rval);
 145 }
 146
 147 struct cond_cancel_info
 148 {
 149         pthread_mutex_t *mutex;
 150         pthread_cond_t  *cond;
 151         int             seqno;
 152         int             count;
 153 };
 154
 155 static void
 156 cond_cancel_handler(void *arg)
 157 {
 158         struct pthread *curthread = tls_get_curthread();
 159         struct cond_cancel_info *info = (struct cond_cancel_info *)arg;
 160         pthread_cond_t cv;
 161
 162         cv = *(info->cond);
 163         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 164         if (--cv->c_waiters == 0)
 165                 cv->c_broadcast = 0;
 166         if (cv->c_seqno != info->seqno) {
 167                 _thr_umtx_wake(&cv->c_seqno, 1);
 168                 /* cv->c_seqno++; XXX why was this here? */
 169                 _thr_umtx_wake(&cv->c_seqno, 1);
 170         }
 171         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 172
 173         _mutex_cv_lock(info->mutex, info->count);
 174 }
 175
 176 static int
 177 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
 178         const struct timespec *abstime, int cancel)
 179 {
 180         struct pthread  *curthread = tls_get_curthread();
 181         struct timespec ts, ts2, *tsp;
 182         struct cond_cancel_info info;
 183         pthread_cond_t  cv;
 184         int             seq, oldseq;
 185         int             oldcancel;
 186         int             ret = 0;
 187
 188         /*
 189          * If the condition variable is statically initialized,
 190          * perform the dynamic initialization:
 191          */
 192         if (__predict_false(*cond == NULL &&
 193             (ret = init_static(curthread, cond)) != 0))
 194                 return (ret);
 195
 196         cv = *cond;
 197 /*      fprintf(stderr, "waiton1 %p\n", cv);*/
 198         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 199         oldseq = cv->c_seqno;
 200 /*      fprintf(stderr, "waiton2 %p %d\n", cv, oldseq);*/
 201         ret = _mutex_cv_unlock(mutex, &info.count);
 202         if (ret) {
 203                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 204                 return (ret);
 205         }
 206         seq = cv->c_seqno;
 207         info.mutex = mutex;
 208         info.cond  = cond;
 209         info.seqno = oldseq;
 210
 211         ++cv->c_waiters;
 212
 213         /*
 214          * loop if we have never been told to wake up
 215          * or we lost a race.
 216          */
 217         while (seq == oldseq /* || cv->c_wakeups == 0*/) {
 218                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 219
 220                 if (abstime != NULL) {
 221                         clock_gettime(cv->c_clockid, &ts);
 222                         TIMESPEC_SUB(&ts2, abstime, &ts);
 223                         tsp = &ts2;
 224                 } else
 225                         tsp = NULL;
 226
 227                 if (cancel) {
 228                         THR_CLEANUP_PUSH(curthread, cond_cancel_handler, &info);
 229                         oldcancel = _thr_cancel_enter(curthread);
 230                         ret = _thr_umtx_wait(&cv->c_seqno, seq, tsp,
 231                                 cv->c_clockid);
 232                         _thr_cancel_leave(curthread, oldcancel);
 233                         THR_CLEANUP_POP(curthread, 0);
 234                 } else {
 235                         ret = _thr_umtx_wait(&cv->c_seqno, seq, tsp,
 236                                 cv->c_clockid);
 237                 }
 238
 239                 THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 240                 seq = cv->c_seqno;
 241                 if (abstime != NULL && ret == ETIMEDOUT)
 242                         break;
 243         }
 244         if (--cv->c_waiters == 0)
 245                 cv->c_broadcast = 0;
 246         if (seq != oldseq)
 247                 ret = 0;
 248         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 249         _mutex_cv_lock(mutex, info.count);
 250         return (ret);
 251 }
 252
 253 int
 254 _pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 255 {
 256
 257         return (cond_wait_common(cond, mutex, NULL, 0));
 258 }
 259
 260 int
 261 __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 262 {
 263
 264         return (cond_wait_common(cond, mutex, NULL, 1));
 265 }
 266
 267 int
 268 _pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
 269                        const struct timespec * abstime)
 270 {
 271         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 272             abstime->tv_nsec >= 1000000000)
 273                 return (EINVAL);
 274
 275         return (cond_wait_common(cond, mutex, abstime, 0));
 276 }
 277
 278 int
 279 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
 280                        const struct timespec *abstime)
 281 {
 282         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 283             abstime->tv_nsec >= 1000000000)
 284                 return (EINVAL);
 285
 286         return (cond_wait_common(cond, mutex, abstime, 1));
 287 }
 288
 289 static int
 290 cond_signal_common(pthread_cond_t *cond, int broadcast)
 291 {
 292         struct pthread  *curthread = tls_get_curthread();
 293         pthread_cond_t  cv;
 294         int             ret = 0;
 295
 296         /*
 297          * If the condition variable is statically initialized, perform dynamic
 298          * initialization.
 299          */
 300         if (__predict_false(*cond == NULL &&
 301             (ret = init_static(curthread, cond)) != 0))
 302                 return (ret);
 303
 304         cv = *cond;
 305 /*      fprintf(stderr, "signal %p\n", cv);*/
 306         /* Lock the condition variable structure. */
 307         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 308         cv->c_seqno++;
 309         if (cv->c_broadcast == 0)
 310                 cv->c_broadcast = broadcast;
 311
 312         if (cv->c_waiters) {
 313                 if (cv->c_broadcast)
 314                         _thr_umtx_wake(&cv->c_seqno, INT_MAX);
 315                 else
 316                         _thr_umtx_wake(&cv->c_seqno, 1);
 317         }
 318         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 319         return (ret);
 320 }
 321
 322 int
 323 _pthread_cond_signal(pthread_cond_t * cond)
 324 {
 325
 326         return (cond_signal_common(cond, 0));
 327 }
 328
 329 int
 330 _pthread_cond_broadcast(pthread_cond_t * cond)
 331 {
 332
 333         return (cond_signal_common(cond, 1));
 334 }
 335
 336 /*
 337  * Double underscore versions are cancellation points.  Single underscore
 338  * versions are not and are provided for libc internal usage (which
 339  * shouldn't introduce cancellation points).
 340  */
 341 __strong_reference(__pthread_cond_wait, pthread_cond_wait);
 342 __strong_reference(__pthread_cond_timedwait, pthread_cond_timedwait);
 343
 344 __strong_reference(_pthread_cond_init, pthread_cond_init);
 345 __strong_reference(_pthread_cond_destroy, pthread_cond_destroy);
 346 __strong_reference(_pthread_cond_signal, pthread_cond_signal);
 347 __strong_reference(_pthread_cond_broadcast, pthread_cond_broadcast);
 348