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 1.10 2006/04/06 23:50:13 davidxu 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_wakeups = 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 + (*cond)->c_wakeups != 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_seqno != info->seqno && cv->c_wakeups != 0) {
 165                 if (cv->c_waiters > 0) {
 166                         cv->c_seqno++;
 167                         _thr_umtx_wake(&cv->c_seqno, 1);
 168                 } else
 169                         cv->c_wakeups--;
 170         } else {
 171                 cv->c_waiters--;
 172         }
 173         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 174
 175         _mutex_cv_lock(info->mutex, info->count);
 176 }
 177
 178 static int
 179 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
 180         const struct timespec *abstime, int cancel)
 181 {
 182         struct pthread  *curthread = tls_get_curthread();
 183         struct timespec ts, ts2, *tsp;
 184         struct cond_cancel_info info;
 185         pthread_cond_t  cv;
 186         int             seq, oldseq;
 187         int             oldcancel;
 188         int             ret = 0;
 189
 190         /*
 191          * If the condition variable is statically initialized,
 192          * perform the dynamic initialization:
 193          */
 194         if (__predict_false(*cond == NULL &&
 195             (ret = init_static(curthread, cond)) != 0))
 196                 return (ret);
 197
 198         cv = *cond;
 199         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 200         ret = _mutex_cv_unlock(mutex, &info.count);
 201         if (ret) {
 202                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 203                 return (ret);
 204         }
 205         oldseq = seq = cv->c_seqno;
 206         info.mutex = mutex;
 207         info.cond  = cond;
 208         info.seqno = oldseq;
 209
 210         cv->c_waiters++;
 211         do {
 212                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 213
 214                 if (abstime != NULL) {
 215                         clock_gettime(cv->c_clockid, &ts);
 216                         TIMESPEC_SUB(&ts2, abstime, &ts);
 217                         tsp = &ts2;
 218                 } else
 219                         tsp = NULL;
 220
 221                 if (cancel) {
 222                         THR_CLEANUP_PUSH(curthread, cond_cancel_handler, &info);
 223                         oldcancel = _thr_cancel_enter(curthread);
 224                         ret = _thr_umtx_wait(&cv->c_seqno, seq, tsp,
 225                                 cv->c_clockid);
 226                         _thr_cancel_leave(curthread, oldcancel);
 227                         THR_CLEANUP_POP(curthread, 0);
 228                 } else {
 229                         ret = _thr_umtx_wait(&cv->c_seqno, seq, tsp,
 230                                 cv->c_clockid);
 231                 }
 232
 233                 THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 234                 seq = cv->c_seqno;
 235                 if (abstime != NULL && ret == ETIMEDOUT)
 236                         break;
 237
 238                 /*
 239                  * loop if we have never been told to wake up
 240                  * or we lost a race.
 241                  */
 242         } while (seq == oldseq || cv->c_wakeups == 0);
 243
 244         if (seq != oldseq && cv->c_wakeups != 0) {
 245                 cv->c_wakeups--;
 246                 ret = 0;
 247         } else {
 248                 cv->c_waiters--;
 249         }
 250         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 251         _mutex_cv_lock(mutex, info.count);
 252         return (ret);
 253 }
 254
 255 int
 256 _pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 257 {
 258
 259         return (cond_wait_common(cond, mutex, NULL, 0));
 260 }
 261
 262 int
 263 __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 264 {
 265
 266         return (cond_wait_common(cond, mutex, NULL, 1));
 267 }
 268
 269 int
 270 _pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
 271                        const struct timespec * abstime)
 272 {
 273         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 274             abstime->tv_nsec >= 1000000000)
 275                 return (EINVAL);
 276
 277         return (cond_wait_common(cond, mutex, abstime, 0));
 278 }
 279
 280 int
 281 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
 282                        const struct timespec *abstime)
 283 {
 284         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 285             abstime->tv_nsec >= 1000000000)
 286                 return (EINVAL);
 287
 288         return (cond_wait_common(cond, mutex, abstime, 1));
 289 }
 290
 291 static int
 292 cond_signal_common(pthread_cond_t *cond, int broadcast)
 293 {
 294         struct pthread  *curthread = tls_get_curthread();
 295         pthread_cond_t  cv;
 296         int             ret = 0;
 297
 298         /*
 299          * If the condition variable is statically initialized, perform dynamic
 300          * initialization.
 301          */
 302         if (__predict_false(*cond == NULL &&
 303             (ret = init_static(curthread, cond)) != 0))
 304                 return (ret);
 305
 306         cv = *cond;
 307         /* Lock the condition variable structure. */
 308         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 309         if (cv->c_waiters) {
 310                 if (!broadcast) {
 311                         cv->c_wakeups++;
 312                         cv->c_waiters--;
 313                         cv->c_seqno++;
 314                         _thr_umtx_wake(&cv->c_seqno, 1);
 315                 } else {
 316                         cv->c_wakeups += cv->c_waiters;
 317                         cv->c_waiters = 0;
 318                         cv->c_seqno++;
 319                         _thr_umtx_wake(&cv->c_seqno, INT_MAX);
 320                 }
 321         }
 322         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 323         return (ret);
 324 }
 325
 326 int
 327 _pthread_cond_signal(pthread_cond_t * cond)
 328 {
 329
 330         return (cond_signal_common(cond, 0));
 331 }
 332
 333 int
 334 _pthread_cond_broadcast(pthread_cond_t * cond)
 335 {
 336
 337         return (cond_signal_common(cond, 1));
 338 }
 339
 340 /*
 341  * Double underscore versions are cancellation points.  Single underscore
 342  * versions are not and are provided for libc internal usage (which
 343  * shouldn't introduce cancellation points).
 344  */
 345 __strong_reference(__pthread_cond_wait, pthread_cond_wait);
 346 __strong_reference(__pthread_cond_timedwait, pthread_cond_timedwait);
 347
 348 __strong_reference(_pthread_cond_init, pthread_cond_init);
 349 __strong_reference(_pthread_cond_destroy, pthread_cond_destroy);
 350 __strong_reference(_pthread_cond_signal, pthread_cond_signal);
 351 __strong_reference(_pthread_cond_broadcast, pthread_cond_broadcast);
 352