Home | History | Annotate | Download | only in c11 
      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 xtime *xt)
    136 {
    137     struct timespec abs_time;
    138     int rt;
    139 
    140     assert(mtx != NULL);
    141     assert(cond != NULL);
    142     assert(xt != NULL);
    143 
    144     abs_time.tv_sec = xt->sec;
    145     abs_time.tv_nsec = xt->nsec;
    146 
    147     rt = pthread_cond_timedwait(cond, mtx, &abs_time);
    148     if (rt == ETIMEDOUT)
    149         return thrd_busy;
    150     return (rt == 0) ? thrd_success : thrd_error;
    151 }
    152 
    153 // 7.25.3.6
    154 static inline int
    155 cnd_wait(cnd_t *cond, mtx_t *mtx)
    156 {
    157     assert(mtx != NULL);
    158     assert(cond != NULL);
    159     return (pthread_cond_wait(cond, mtx) == 0) ? thrd_success : thrd_error;
    160 }
    161 
    162 
    163 /*-------------------- 7.25.4 Mutex functions --------------------*/
    164 // 7.25.4.1
    165 static inline void
    166 mtx_destroy(mtx_t *mtx)
    167 {
    168     assert(mtx != NULL);
    169     pthread_mutex_destroy(mtx);
    170 }
    171 
    172 // 7.25.4.2
    173 static inline int
    174 mtx_init(mtx_t *mtx, int type)
    175 {
    176     pthread_mutexattr_t attr;
    177     assert(mtx != NULL);
    178     if (type != mtx_plain && type != mtx_timed && type != mtx_try
    179       && type != (mtx_plain|mtx_recursive)
    180       && type != (mtx_timed|mtx_recursive)
    181       && type != (mtx_try|mtx_recursive))
    182         return thrd_error;
    183     pthread_mutexattr_init(&attr);
    184     if ((type & mtx_recursive) != 0)
    185         pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
    186     pthread_mutex_init(mtx, &attr);
    187     pthread_mutexattr_destroy(&attr);
    188     return thrd_success;
    189 }
    190 
    191 // 7.25.4.3
    192 static inline int
    193 mtx_lock(mtx_t *mtx)
    194 {
    195     assert(mtx != NULL);
    196     return (pthread_mutex_lock(mtx) == 0) ? thrd_success : thrd_error;
    197 }
    198 
    199 static inline int
    200 mtx_trylock(mtx_t *mtx);
    201 
    202 static inline void
    203 thrd_yield(void);
    204 
    205 // 7.25.4.4
    206 static inline int
    207 mtx_timedlock(mtx_t *mtx, const xtime *xt)
    208 {
    209     assert(mtx != NULL);
    210     assert(xt != NULL);
    211 
    212     {
    213 #ifdef EMULATED_THREADS_USE_NATIVE_TIMEDLOCK
    214     struct timespec ts;
    215     int rt;
    216     ts.tv_sec = xt->sec;
    217     ts.tv_nsec = xt->nsec;
    218     rt = pthread_mutex_timedlock(mtx, &ts);
    219     if (rt == 0)
    220         return thrd_success;
    221     return (rt == ETIMEDOUT) ? thrd_busy : thrd_error;
    222 #else
    223     time_t expire = time(NULL);
    224     expire += xt->sec;
    225     while (mtx_trylock(mtx) != thrd_success) {
    226         time_t now = time(NULL);
    227         if (expire < now)
    228             return thrd_busy;
    229         // busy loop!
    230         thrd_yield();
    231     }
    232     return thrd_success;
    233 #endif
    234     }
    235 }
    236 
    237 // 7.25.4.5
    238 static inline int
    239 mtx_trylock(mtx_t *mtx)
    240 {
    241     assert(mtx != NULL);
    242     return (pthread_mutex_trylock(mtx) == 0) ? thrd_success : thrd_busy;
    243 }
    244 
    245 // 7.25.4.6
    246 static inline int
    247 mtx_unlock(mtx_t *mtx)
    248 {
    249     assert(mtx != NULL);
    250     return (pthread_mutex_unlock(mtx) == 0) ? thrd_success : thrd_error;
    251 }
    252 
    253 
    254 /*------------------- 7.25.5 Thread functions -------------------*/
    255 // 7.25.5.1
    256 static inline int
    257 thrd_create(thrd_t *thr, thrd_start_t func, void *arg)
    258 {
    259     struct impl_thrd_param *pack;
    260     assert(thr != NULL);
    261     pack = (struct impl_thrd_param *)malloc(sizeof(struct impl_thrd_param));
    262     if (!pack) return thrd_nomem;
    263     pack->func = func;
    264     pack->arg = arg;
    265     if (pthread_create(thr, NULL, impl_thrd_routine, pack) != 0) {
    266         free(pack);
    267         return thrd_error;
    268     }
    269     return thrd_success;
    270 }
    271 
    272 // 7.25.5.2
    273 static inline thrd_t
    274 thrd_current(void)
    275 {
    276     return pthread_self();
    277 }
    278 
    279 // 7.25.5.3
    280 static inline int
    281 thrd_detach(thrd_t thr)
    282 {
    283     return (pthread_detach(thr) == 0) ? thrd_success : thrd_error;
    284 }
    285 
    286 // 7.25.5.4
    287 static inline int
    288 thrd_equal(thrd_t thr0, thrd_t thr1)
    289 {
    290     return pthread_equal(thr0, thr1);
    291 }
    292 
    293 // 7.25.5.5
    294 static inline void
    295 thrd_exit(int res)
    296 {
    297     pthread_exit((void*)(intptr_t)res);
    298 }
    299 
    300 // 7.25.5.6
    301 static inline int
    302 thrd_join(thrd_t thr, int *res)
    303 {
    304     void *code;
    305     if (pthread_join(thr, &code) != 0)
    306         return thrd_error;
    307     if (res)
    308         *res = (int)(intptr_t)code;
    309     return thrd_success;
    310 }
    311 
    312 // 7.25.5.7
    313 static inline void
    314 thrd_sleep(const xtime *xt)
    315 {
    316     struct timespec req;
    317     assert(xt);
    318     req.tv_sec = xt->sec;
    319     req.tv_nsec = xt->nsec;
    320     nanosleep(&req, NULL);
    321 }
    322 
    323 // 7.25.5.8
    324 static inline void
    325 thrd_yield(void)
    326 {
    327     sched_yield();
    328 }
    329 
    330 
    331 /*----------- 7.25.6 Thread-specific storage functions -----------*/
    332 // 7.25.6.1
    333 static inline int
    334 tss_create(tss_t *key, tss_dtor_t dtor)
    335 {
    336     assert(key != NULL);
    337     return (pthread_key_create(key, dtor) == 0) ? thrd_success : thrd_error;
    338 }
    339 
    340 // 7.25.6.2
    341 static inline void
    342 tss_delete(tss_t key)
    343 {
    344     pthread_key_delete(key);
    345 }
    346 
    347 // 7.25.6.3
    348 static inline void *
    349 tss_get(tss_t key)
    350 {
    351     return pthread_getspecific(key);
    352 }
    353 
    354 // 7.25.6.4
    355 static inline int
    356 tss_set(tss_t key, void *val)
    357 {
    358     return (pthread_setspecific(key, val) == 0) ? thrd_success : thrd_error;
    359 }
    360 
    361 
    362 /*-------------------- 7.25.7 Time functions --------------------*/
    363 // 7.25.6.1
    364 static inline int
    365 xtime_get(xtime *xt, int base)
    366 {
    367     if (!xt) return 0;
    368     if (base == TIME_UTC) {
    369         xt->sec = time(NULL);
    370         xt->nsec = 0;
    371         return base;
    372     }
    373     return 0;
    374 }
    375