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 1.9 2006/04/06 13:05:35 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         long            seqno;
 152 };
 153
 154 static void
 155 cond_cancel_handler(void *arg)
 156 {
 157         struct pthread *curthread = tls_get_curthread();
 158         struct cond_cancel_info *cci = (struct cond_cancel_info *)arg;
 159         pthread_cond_t cv;
 160
 161         cv = *(cci->cond);
 162         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 163         if (cv->c_seqno != cci->seqno && cv->c_wakeups != 0) {
 164                 if (cv->c_waiters > 0) {
 165                         cv->c_seqno++;
 166                         _thr_umtx_wake(&cv->c_seqno, 1);
 167                 } else
 168                         cv->c_wakeups--;
 169         } else {
 170                 cv->c_waiters--;
 171         }
 172         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 173
 174         _mutex_cv_lock(cci->mutex);
 175 }
 176
 177 static int
 178 cond_wait_common(pthread_cond_t *cond, pthread_mutex_t *mutex,
 179         const struct timespec *abstime, int cancel)
 180 {
 181         struct pthread  *curthread = tls_get_curthread();
 182         struct timespec ts, ts2, *tsp;
 183         struct cond_cancel_info cci;
 184         pthread_cond_t  cv;
 185         int             seq, oldseq;
 186         int             oldcancel;
 187         int             ret = 0;
 188
 189         /*
 190          * If the condition variable is statically initialized,
 191          * perform the dynamic initialization:
 192          */
 193         if (__predict_false(*cond == NULL &&
 194             (ret = init_static(curthread, cond)) != 0))
 195                 return (ret);
 196
 197         cv = *cond;
 198         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 199         ret = _mutex_cv_unlock(mutex);
 200         if (ret) {
 201                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 202                 return (ret);
 203         }
 204         oldseq = seq = cv->c_seqno;
 205         cci.mutex = mutex;
 206         cci.cond  = cond;
 207         cci.seqno = oldseq;
 208
 209         cv->c_waiters++;
 210         do {
 211                 THR_LOCK_RELEASE(curthread, &cv->c_lock);
 212
 213                 if (abstime != NULL) {
 214                         clock_gettime(cv->c_clockid, &ts);
 215                         TIMESPEC_SUB(&ts2, abstime, &ts);
 216                         tsp = &ts2;
 217                 } else
 218                         tsp = NULL;
 219
 220                 if (cancel) {
 221                         THR_CLEANUP_PUSH(curthread, cond_cancel_handler, &cci);
 222                         oldcancel = _thr_cancel_enter(curthread);
 223                         ret = _thr_umtx_wait(&cv->c_seqno, seq, tsp,
 224                                 cv->c_clockid);
 225                         _thr_cancel_leave(curthread, oldcancel);
 226                         THR_CLEANUP_POP(curthread, 0);
 227                 } else {
 228                         ret = _thr_umtx_wait(&cv->c_seqno, seq, tsp,
 229                                 cv->c_clockid);
 230                 }
 231
 232                 THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 233                 seq = cv->c_seqno;
 234                 if (abstime != NULL && ret == ETIMEDOUT)
 235                         break;
 236
 237                 /*
 238                  * loop if we have never been told to wake up
 239                  * or we lost a race.
 240                  */
 241         } while (seq == oldseq || cv->c_wakeups == 0);
 242
 243         if (seq != oldseq && cv->c_wakeups != 0) {
 244                 cv->c_wakeups--;
 245                 ret = 0;
 246         } else {
 247                 cv->c_waiters--;
 248         }
 249         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 250         _mutex_cv_lock(mutex);
 251         return (ret);
 252 }
 253
 254 int
 255 _pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 256 {
 257
 258         return (cond_wait_common(cond, mutex, NULL, 0));
 259 }
 260
 261 int
 262 __pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
 263 {
 264
 265         return (cond_wait_common(cond, mutex, NULL, 1));
 266 }
 267
 268 int
 269 _pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
 270                        const struct timespec * abstime)
 271 {
 272         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 273             abstime->tv_nsec >= 1000000000)
 274                 return (EINVAL);
 275
 276         return (cond_wait_common(cond, mutex, abstime, 0));
 277 }
 278
 279 int
 280 __pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
 281                        const struct timespec *abstime)
 282 {
 283         if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
 284             abstime->tv_nsec >= 1000000000)
 285                 return (EINVAL);
 286
 287         return (cond_wait_common(cond, mutex, abstime, 1));
 288 }
 289
 290 static int
 291 cond_signal_common(pthread_cond_t *cond, int broadcast)
 292 {
 293         struct pthread  *curthread = tls_get_curthread();
 294         pthread_cond_t  cv;
 295         int             ret = 0;
 296
 297         /*
 298          * If the condition variable is statically initialized, perform dynamic
 299          * initialization.
 300          */
 301         if (__predict_false(*cond == NULL &&
 302             (ret = init_static(curthread, cond)) != 0))
 303                 return (ret);
 304
 305         cv = *cond;
 306         /* Lock the condition variable structure. */
 307         THR_LOCK_ACQUIRE(curthread, &cv->c_lock);
 308         if (cv->c_waiters) {
 309                 if (!broadcast) {
 310                         cv->c_wakeups++;
 311                         cv->c_waiters--;
 312                         cv->c_seqno++;
 313                         _thr_umtx_wake(&cv->c_seqno, 1);
 314                 } else {
 315                         cv->c_wakeups += cv->c_waiters;
 316                         cv->c_waiters = 0;
 317                         cv->c_seqno++;
 318                         _thr_umtx_wake(&cv->c_seqno, INT_MAX);
 319                 }
 320         }
 321         THR_LOCK_RELEASE(curthread, &cv->c_lock);
 322         return (ret);
 323 }
 324
 325 int
 326 _pthread_cond_signal(pthread_cond_t * cond)
 327 {
 328
 329         return (cond_signal_common(cond, 0));
 330 }
 331
 332 int
 333 _pthread_cond_broadcast(pthread_cond_t * cond)
 334 {
 335
 336         return (cond_signal_common(cond, 1));
 337 }
 338
 339 /*
 340  * Double underscore versions are cancellation points.  Single underscore
 341  * versions are not and are provided for libc internal usage (which
 342  * shouldn't introduce cancellation points).
 343  */
 344 __strong_reference(__pthread_cond_wait, pthread_cond_wait);
 345 __strong_reference(__pthread_cond_timedwait, pthread_cond_timedwait);
 346
 347 __strong_reference(_pthread_cond_init, pthread_cond_init);
 348 __strong_reference(_pthread_cond_destroy, pthread_cond_destroy);
 349 __strong_reference(_pthread_cond_signal, pthread_cond_signal);
 350 __strong_reference(_pthread_cond_broadcast, pthread_cond_broadcast);
 351