1 /* ISO C11 Standard: 7.26 - Thread support library <threads.h>.
2 Copyright (C) 2018-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #ifndef _THREADS_H
20 #define _THREADS_H 1
21
22 #include <features.h>
23 #include <time.h>
24
25 __BEGIN_DECLS
26
27 #include <bits/thread-shared-types.h>
28 #include <bits/types/struct_timespec.h>
29
30 #ifndef __cplusplus
31 # define thread_local _Thread_local
32 #endif
33
34 #define TSS_DTOR_ITERATIONS 4
35 typedef __tss_t tss_t;
36 typedef void (*tss_dtor_t) (void*);
37
38 typedef __thrd_t thrd_t;
39 typedef int (*thrd_start_t) (void*);
40
41 /* Exit and error codes. */
42 enum
43 {
44 thrd_success = 0,
45 thrd_busy = 1,
46 thrd_error = 2,
47 thrd_nomem = 3,
48 thrd_timedout = 4
49 };
50
51 /* Mutex types. */
52 enum
53 {
54 mtx_plain = 0,
55 mtx_recursive = 1,
56 mtx_timed = 2
57 };
58
59 typedef __once_flag once_flag;
60 #define ONCE_FLAG_INIT __ONCE_FLAG_INIT
61
62 typedef union
63 {
64 char __size[__SIZEOF_PTHREAD_MUTEX_T];
65 long int __align __LOCK_ALIGNMENT;
66 } mtx_t;
67
68 typedef union
69 {
70 char __size[__SIZEOF_PTHREAD_COND_T];
71 __extension__ long long int __align __LOCK_ALIGNMENT;
72 } cnd_t;
73
74 /* Threads functions. */
75
76 /* Create a new thread executing the function __FUNC. Arguments for __FUNC
77 are passed through __ARG. If succesful, __THR is set to new thread
78 identifier. */
79 extern int thrd_create (thrd_t *__thr, thrd_start_t __func, void *__arg);
80
81 /* Check if __LHS and __RHS point to the same thread. */
82 extern int thrd_equal (thrd_t __lhs, thrd_t __rhs);
83
84 /* Return current thread identifier. */
85 extern thrd_t thrd_current (void);
86
87 /* Block current thread execution for at least the time pointed by
88 __TIME_POINT. The current thread may resume if receives a signal. In
89 that case, if __REMAINING is not NULL, the remaining time is stored in
90 the object pointed by it. */
91 #ifndef __USE_TIME_BITS64
92 extern int thrd_sleep (const struct timespec *__time_point,
93 struct timespec *__remaining);
94 #else
95 # ifdef __REDIRECT
96 extern int __REDIRECT (thrd_sleep, (const struct timespec *__time_point,
97 struct timespec *__remaining),
98 __thrd_sleep64);
99 # else
100 # define thrd_sleep __thrd_sleep64
101 # endif
102 #endif
103
104 /* Terminate current thread execution, cleaning up any thread local
105 storage and freeing resources. Returns the value specified in __RES. */
106 extern void thrd_exit (int __res) __attribute__ ((__noreturn__));
107
108 /* Detach the thread identified by __THR from the current environment
109 (it does not allow join or wait for it). */
110 extern int thrd_detach (thrd_t __thr);
111
112 /* Block current thread until execution of __THR is complete. In case that
113 __RES is not NULL, will store the return value of __THR when exiting. */
114 extern int thrd_join (thrd_t __thr, int *__res);
115
116 /* Stop current thread execution and call the scheduler to decide which
117 thread should execute next. The current thread may be selected by the
118 scheduler to keep running. */
119 extern void thrd_yield (void);
120
121 #ifdef __USE_EXTERN_INLINES
122 /* Optimizations. */
123 __extern_inline int
thrd_equal(thrd_t __thread1,thrd_t __thread2)124 thrd_equal (thrd_t __thread1, thrd_t __thread2)
125 {
126 return __thread1 == __thread2;
127 }
128 #endif
129
130
131 /* Mutex functions. */
132
133 /* Creates a new mutex object with type __TYPE. If successful the new
134 object is pointed by __MUTEX. */
135 extern int mtx_init (mtx_t *__mutex, int __type);
136
137 /* Block the current thread until the mutex pointed to by __MUTEX is
138 unlocked. In that case current thread will not be blocked. */
139 extern int mtx_lock (mtx_t *__mutex);
140
141 /* Block the current thread until the mutex pointed by __MUTEX is unlocked
142 or time pointed by __TIME_POINT is reached. In case the mutex is unlock,
143 the current thread will not be blocked. */
144 #ifndef __USE_TIME_BITS64
145 extern int mtx_timedlock (mtx_t *__restrict __mutex,
146 const struct timespec *__restrict __time_point);
147 #else
148 # ifdef __REDIRECT
149 extern int __REDIRECT (mtx_timedlock, (mtx_t *__restrict __mutex,
150 const struct timespec *__restrict
151 __time_point),
152 __mtx_timedlock64);
153 # else
154 # define mtx_timedlock __mtx_timedlock64
155 # endif
156 #endif
157
158 /* Try to lock the mutex pointed by __MUTEX without blocking. If the mutex
159 is free the current threads takes control of it, otherwise it returns
160 immediately. */
161 extern int mtx_trylock (mtx_t *__mutex);
162
163 /* Unlock the mutex pointed by __MUTEX. It may potentially awake other
164 threads waiting on this mutex. */
165 extern int mtx_unlock (mtx_t *__mutex);
166
167 /* Destroy the mutex object pointed by __MUTEX. */
168 extern void mtx_destroy (mtx_t *__mutex);
169
170
171 /* Call function __FUNC exactly once, even if invoked from several threads.
172 All calls must be made with the same __FLAGS object. */
173 extern void call_once (once_flag *__flag, void (*__func)(void));
174
175
176 /* Condition variable functions. */
177
178 /* Initialize new condition variable pointed by __COND. */
179 extern int cnd_init (cnd_t *__cond);
180
181 /* Unblock one thread that currently waits on condition variable pointed
182 by __COND. */
183 extern int cnd_signal (cnd_t *__cond);
184
185 /* Unblock all threads currently waiting on condition variable pointed by
186 __COND. */
187 extern int cnd_broadcast (cnd_t *__cond);
188
189 /* Block current thread on the condition variable pointed by __COND. */
190 extern int cnd_wait (cnd_t *__cond, mtx_t *__mutex);
191
192 /* Block current thread on the condition variable until condition variable
193 pointed by __COND is signaled or time pointed by __TIME_POINT is
194 reached. */
195 #ifndef __USE_TIME_BITS64
196 extern int cnd_timedwait (cnd_t *__restrict __cond,
197 mtx_t *__restrict __mutex,
198 const struct timespec *__restrict __time_point);
199 #else
200 # ifdef __REDIRECT
201 extern int __REDIRECT (cnd_timedwait, (cnd_t *__restrict __cond,
202 mtx_t *__restrict __mutex,
203 const struct timespec *__restrict
204 __time_point),
205 __cnd_timedwait64);
206 # else
207 # define cnd_timedwait __cnd_timedwait64
208 # endif
209 #endif
210
211 /* Destroy condition variable pointed by __cond and free all of its
212 resources. */
213 extern void cnd_destroy (cnd_t *__COND);
214
215
216 /* Thread specific storage functions. */
217
218 /* Create new thread-specific storage key and stores it in the object pointed
219 by __TSS_ID. If __DESTRUCTOR is not NULL, the function will be called when
220 the thread terminates. */
221 extern int tss_create (tss_t *__tss_id, tss_dtor_t __destructor);
222
223 /* Return the value held in thread-specific storage for the current thread
224 identified by __TSS_ID. */
225 extern void *tss_get (tss_t __tss_id);
226
227 /* Sets the value of the thread-specific storage identified by __TSS_ID for
228 the current thread to __VAL. */
229 extern int tss_set (tss_t __tss_id, void *__val);
230
231 /* Destroys the thread-specific storage identified by __TSS_ID. The
232 destructor is not called until thrd_exit is called. */
233 extern void tss_delete (tss_t __tss_id);
234
235 __END_DECLS
236
237 #endif /* _THREADS_H */
238