include/c11/threads_posix.h

   1 /*
   2  * C11 <threads.h> emulation library
   3  *
   4  * (C) Copyright yohhoy 2012.
   5  * Distributed under the Boost Software License, Version 1.0.
   6  *
   7  * Permission is hereby granted, free of charge, to any person or organization
   8  * obtaining a copy of the software and accompanying documentation covered by
   9  * this license (the "Software") to use, reproduce, display, distribute,
  10  * execute, and transmit the Software, and to prepare [[derivative work]]s of the
  11  * Software, and to permit third-parties to whom the Software is furnished to
  12  * do so, all subject to the following:
  13  *
  14  * The copyright notices in the Software and this entire statement, including
  15  * the above license grant, this restriction and the following disclaimer,
  16  * must be included in all copies of the Software, in whole or in part, and
  17  * all derivative works of the Software, unless such copies or derivative
  18  * works are solely in the form of machine-executable object code generated by
  19  * a source language processor.
  20  *
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
  24  * SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
  25  * FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
  26  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  27  * DEALINGS IN THE SOFTWARE.
  28  */
  29 #include <stdlib.h>
  30 #ifndef assert
  31 #include <assert.h>
  32 #endif
  33 #include <limits.h>
  34 #include <errno.h>
  35 #include <unistd.h>
  36 #include <sched.h>
  37 #include <stdint.h> /* for intptr_t */
  38
  39 /*
  40 Configuration macro:
  41
  42   EMULATED_THREADS_USE_NATIVE_TIMEDLOCK
  43     Use pthread_mutex_timedlock() for `mtx_timedlock()'
  44     Otherwise use mtx_trylock() + *busy loop* emulation.
  45 */
  46 #if !defined(__CYGWIN__) && !defined(__APPLE__) && !defined(__NetBSD__)
  47 #define EMULATED_THREADS_USE_NATIVE_TIMEDLOCK
  48 #endif
  49
  50
  51 #include <pthread.h>
  52
  53 /*---------------------------- macros ----------------------------*/
  54 #define ONCE_FLAG_INIT PTHREAD_ONCE_INIT
  55 #ifdef INIT_ONCE_STATIC_INIT
  56 #define TSS_DTOR_ITERATIONS PTHREAD_DESTRUCTOR_ITERATIONS
  57 #else
  58 #define TSS_DTOR_ITERATIONS 1  // assume TSS dtor MAY be called at least once.
  59 #endif
  60
  61 // FIXME: temporary non-standard hack to ease transition
  62 #define _MTX_INITIALIZER_NP PTHREAD_MUTEX_INITIALIZER
  63
  64 /*---------------------------- types ----------------------------*/
  65 typedef pthread_cond_t  cnd_t;
  66 typedef pthread_t       thrd_t;
  67 typedef pthread_key_t   tss_t;
  68 typedef pthread_mutex_t mtx_t;
  69 typedef pthread_once_t  once_flag;
  70
  71
  72 /*
  73 Implementation limits:
  74   - Conditionally emulation for "mutex with timeout"
  75     (see EMULATED_THREADS_USE_NATIVE_TIMEDLOCK macro)
  76 */
  77 struct impl_thrd_param {
  78     thrd_start_t func;
  79     void *arg;
  80 };
  81
  82 static inline void *
  83 impl_thrd_routine(void *p)
  84 {
  85     struct impl_thrd_param pack = *((struct impl_thrd_param *)p);
  86     free(p);
  87     return (void*)(intptr_t)pack.func(pack.arg);
  88 }
  89
  90
  91 /*--------------- 7.25.2 Initialization functions ---------------*/
  92 // 7.25.2.1
  93 static inline void
  94 call_once(once_flag *flag, void (*func)(void))
  95 {
  96     pthread_once(flag, func);
  97 }
  98
  99
 100 /*------------- 7.25.3 Condition variable functions -------------*/
 101 // 7.25.3.1
 102 static inline int
 103 cnd_broadcast(cnd_t *cond)
 104 {
 105     assert(cond != NULL);
 106     return (pthread_cond_broadcast(cond) == 0) ? thrd_success : thrd_error;
 107 }
 108
 109 // 7.25.3.2
 110 static inline void
 111 cnd_destroy(cnd_t *cond)
 112 {
 113     assert(cond);
 114     pthread_cond_destroy(cond);
 115 }
 116
 117 // 7.25.3.3
 118 static inline int
 119 cnd_init(cnd_t *cond)
 120 {
 121     assert(cond != NULL);
 122     return (pthread_cond_init(cond, NULL) == 0) ? thrd_success : thrd_error;
 123 }
 124
 125 // 7.25.3.4
 126 static inline int
 127 cnd_signal(cnd_t *cond)
 128 {
 129     assert(cond != NULL);
 130     return (pthread_cond_signal(cond) == 0) ? thrd_success : thrd_error;
 131 }
 132
 133 // 7.25.3.5
 134 static inline int
 135 cnd_timedwait(cnd_t *cond, mtx_t *mtx, const struct timespec *abs_time)
 136 {
 137     int rt;
 138
 139     assert(mtx != NULL);
 140     assert(cond != NULL);
 141     assert(abs_time != NULL);
 142
 143     rt = pthread_cond_timedwait(cond, mtx, abs_time);
 144     if (rt == ETIMEDOUT)
 145         return thrd_busy;
 146     return (rt == 0) ? thrd_success : thrd_error;
 147 }
 148
 149 // 7.25.3.6
 150 static inline int
 151 cnd_wait(cnd_t *cond, mtx_t *mtx)
 152 {
 153     assert(mtx != NULL);
 154     assert(cond != NULL);
 155     return (pthread_cond_wait(cond, mtx) == 0) ? thrd_success : thrd_error;
 156 }
 157
 158
 159 /*-------------------- 7.25.4 Mutex functions --------------------*/
 160 // 7.25.4.1
 161 static inline void
 162 mtx_destroy(mtx_t *mtx)
 163 {
 164     assert(mtx != NULL);
 165     pthread_mutex_destroy(mtx);
 166 }
 167
 168 /*
 169  * XXX: Workaround when building with -O0 and without pthreads link.
 170  *
 171  * In such cases constant folding and dead code elimination won't be
 172  * available, thus the compiler will always add the pthread_mutexattr*
 173  * functions into the binary. As we try to link, we'll fail as the
 174  * symbols are unresolved.
 175  *
 176  * Ideally we'll enable the optimisations locally, yet that does not
 177  * seem to work.
 178  *
 179  * So the alternative workaround is to annotate the symbols as weak.
 180  * Thus the linker will be happy and things don't clash when building
 181  * with -O1 or greater.
 182  */
 183 #if defined(HAVE_FUNC_ATTRIBUTE_WEAK) && !defined(__CYGWIN__)
 184 __attribute__((weak))
 185 int pthread_mutexattr_init(pthread_mutexattr_t *attr);
 186
 187 __attribute__((weak))
 188 int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type);
 189
 190 __attribute__((weak))
 191 int pthread_mutexattr_destroy(pthread_mutexattr_t *attr);
 192 #endif
 193
 194 // 7.25.4.2
 195 static inline int
 196 mtx_init(mtx_t *mtx, int type)
 197 {
 198     pthread_mutexattr_t attr;
 199     assert(mtx != NULL);
 200     if (type != mtx_plain && type != mtx_timed && type != mtx_try
 201       && type != (mtx_plain|mtx_recursive)
 202       && type != (mtx_timed|mtx_recursive)
 203       && type != (mtx_try|mtx_recursive))
 204         return thrd_error;
 205
 206     if ((type & mtx_recursive) == 0) {
 207         pthread_mutex_init(mtx, NULL);
 208         return thrd_success;
 209     }
 210
 211     pthread_mutexattr_init(&attr);
 212     pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
 213     pthread_mutex_init(mtx, &attr);
 214     pthread_mutexattr_destroy(&attr);
 215     return thrd_success;
 216 }
 217
 218 // 7.25.4.3
 219 static inline int
 220 mtx_lock(mtx_t *mtx)
 221 {
 222     assert(mtx != NULL);
 223     return (pthread_mutex_lock(mtx) == 0) ? thrd_success : thrd_error;
 224 }
 225
 226 static inline int
 227 mtx_trylock(mtx_t *mtx);
 228
 229 static inline void
 230 thrd_yield(void);
 231
 232 // 7.25.4.4
 233 static inline int
 234 mtx_timedlock(mtx_t *mtx, const struct timespec *ts)
 235 {
 236     assert(mtx != NULL);
 237     assert(ts != NULL);
 238
 239     {
 240 #ifdef EMULATED_THREADS_USE_NATIVE_TIMEDLOCK
 241     int rt;
 242     rt = pthread_mutex_timedlock(mtx, ts);
 243     if (rt == 0)
 244         return thrd_success;
 245     return (rt == ETIMEDOUT) ? thrd_busy : thrd_error;
 246 #else
 247     time_t expire = time(NULL);
 248     expire += ts->tv_sec;
 249     while (mtx_trylock(mtx) != thrd_success) {
 250         time_t now = time(NULL);
 251         if (expire < now)
 252             return thrd_busy;
 253         // busy loop!
 254         thrd_yield();
 255     }
 256     return thrd_success;
 257 #endif
 258     }
 259 }
 260
 261 // 7.25.4.5
 262 static inline int
 263 mtx_trylock(mtx_t *mtx)
 264 {
 265     assert(mtx != NULL);
 266     return (pthread_mutex_trylock(mtx) == 0) ? thrd_success : thrd_busy;
 267 }
 268
 269 // 7.25.4.6
 270 static inline int
 271 mtx_unlock(mtx_t *mtx)
 272 {
 273     assert(mtx != NULL);
 274     return (pthread_mutex_unlock(mtx) == 0) ? thrd_success : thrd_error;
 275 }
 276
 277
 278 /*------------------- 7.25.5 Thread functions -------------------*/
 279 // 7.25.5.1
 280 static inline int
 281 thrd_create(thrd_t *thr, thrd_start_t func, void *arg)
 282 {
 283     struct impl_thrd_param *pack;
 284     assert(thr != NULL);
 285     pack = (struct impl_thrd_param *)malloc(sizeof(struct impl_thrd_param));
 286     if (!pack) return thrd_nomem;
 287     pack->func = func;
 288     pack->arg = arg;
 289     if (pthread_create(thr, NULL, impl_thrd_routine, pack) != 0) {
 290         free(pack);
 291         return thrd_error;
 292     }
 293     return thrd_success;
 294 }
 295
 296 // 7.25.5.2
 297 static inline thrd_t
 298 thrd_current(void)
 299 {
 300     return pthread_self();
 301 }
 302
 303 // 7.25.5.3
 304 static inline int
 305 thrd_detach(thrd_t thr)
 306 {
 307     return (pthread_detach(thr) == 0) ? thrd_success : thrd_error;
 308 }
 309
 310 // 7.25.5.4
 311 static inline int
 312 thrd_equal(thrd_t thr0, thrd_t thr1)
 313 {
 314     return pthread_equal(thr0, thr1);
 315 }
 316
 317 // 7.25.5.5
 318 static inline void
 319 thrd_exit(int res)
 320 {
 321     pthread_exit((void*)(intptr_t)res);
 322 }
 323
 324 // 7.25.5.6
 325 static inline int
 326 thrd_join(thrd_t thr, int *res)
 327 {
 328     void *code;
 329     if (pthread_join(thr, &code) != 0)
 330         return thrd_error;
 331     if (res)
 332         *res = (int)(intptr_t)code;
 333     return thrd_success;
 334 }
 335
 336 // 7.25.5.7
 337 static inline void
 338 thrd_sleep(const struct timespec *time_point, struct timespec *remaining)
 339 {
 340     assert(time_point != NULL);
 341     nanosleep(time_point, remaining);
 342 }
 343
 344 // 7.25.5.8
 345 static inline void
 346 thrd_yield(void)
 347 {
 348     sched_yield();
 349 }
 350
 351
 352 /*----------- 7.25.6 Thread-specific storage functions -----------*/
 353 // 7.25.6.1
 354 static inline int
 355 tss_create(tss_t *key, tss_dtor_t dtor)
 356 {
 357     assert(key != NULL);
 358     return (pthread_key_create(key, dtor) == 0) ? thrd_success : thrd_error;
 359 }
 360
 361 // 7.25.6.2
 362 static inline void
 363 tss_delete(tss_t key)
 364 {
 365     pthread_key_delete(key);
 366 }
 367
 368 // 7.25.6.3
 369 static inline void *
 370 tss_get(tss_t key)
 371 {
 372     return pthread_getspecific(key);
 373 }
 374
 375 // 7.25.6.4
 376 static inline int
 377 tss_set(tss_t key, void *val)
 378 {
 379     return (pthread_setspecific(key, val) == 0) ? thrd_success : thrd_error;
 380 }
 381
 382
 383 /*-------------------- 7.25.7 Time functions --------------------*/
 384 // 7.25.6.1
 385 #ifndef HAVE_TIMESPEC_GET
 386 static inline int
 387 timespec_get(struct timespec *ts, int base)
 388 {
 389     if (!ts) return 0;
 390     if (base == TIME_UTC) {
 391         clock_gettime(CLOCK_REALTIME, ts);
 392         return base;
 393     }
 394     return 0;
 395 }
 396 #endif