1/* ISO C11 Standard: 7.26 - Thread support library <threads.h>.
2 Copyright (C) 2018-2023 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#if (!defined __STDC_VERSION__ \
31 || __STDC_VERSION__ <= 201710L \
32 || !__GNUC_PREREQ (13, 0)) && !defined __cplusplus
33# define thread_local _Thread_local
34#endif
35
36#define TSS_DTOR_ITERATIONS 4
37typedef __tss_t tss_t;
38typedef void (*tss_dtor_t) (void*);
39
40typedef __thrd_t thrd_t;
41typedef int (*thrd_start_t) (void*);
42
43/* Exit and error codes. */
44enum
45{
46 thrd_success = 0,
47 thrd_busy = 1,
48 thrd_error = 2,
49 thrd_nomem = 3,
50 thrd_timedout = 4
51};
52
53/* Mutex types. */
54enum
55{
56 mtx_plain = 0,
57 mtx_recursive = 1,
58 mtx_timed = 2
59};
60
61typedef __once_flag once_flag;
62#define ONCE_FLAG_INIT __ONCE_FLAG_INIT
63
64typedef union
65{
66 char __size[__SIZEOF_PTHREAD_MUTEX_T];
67 long int __align __LOCK_ALIGNMENT;
68} mtx_t;
69
70typedef union
71{
72 char __size[__SIZEOF_PTHREAD_COND_T];
73 __extension__ long long int __align __LOCK_ALIGNMENT;
74} cnd_t;
75
76/* Threads functions. */
77
78/* Create a new thread executing the function __FUNC. Arguments for __FUNC
79 are passed through __ARG. If succesful, __THR is set to new thread
80 identifier. */
81extern int thrd_create (thrd_t *__thr, thrd_start_t __func, void *__arg);
82
83/* Check if __LHS and __RHS point to the same thread. */
84extern int thrd_equal (thrd_t __lhs, thrd_t __rhs);
85
86/* Return current thread identifier. */
87extern thrd_t thrd_current (void);
88
89/* Block current thread execution for at least the time pointed by
90 __TIME_POINT. The current thread may resume if receives a signal. In
91 that case, if __REMAINING is not NULL, the remaining time is stored in
92 the object pointed by it. */
93#ifndef __USE_TIME_BITS64
94extern int thrd_sleep (const struct timespec *__time_point,
95 struct timespec *__remaining);
96#else
97# ifdef __REDIRECT
98extern int __REDIRECT (thrd_sleep, (const struct timespec *__time_point,
99 struct timespec *__remaining),
100 __thrd_sleep64);
101# else
102# define thrd_sleep __thrd_sleep64
103# endif
104#endif
105
106/* Terminate current thread execution, cleaning up any thread local
107 storage and freeing resources. Returns the value specified in __RES. */
108extern void thrd_exit (int __res) __attribute__ ((__noreturn__));
109
110/* Detach the thread identified by __THR from the current environment
111 (it does not allow join or wait for it). */
112extern int thrd_detach (thrd_t __thr);
113
114/* Block current thread until execution of __THR is complete. In case that
115 __RES is not NULL, will store the return value of __THR when exiting. */
116extern int thrd_join (thrd_t __thr, int *__res);
117
118/* Stop current thread execution and call the scheduler to decide which
119 thread should execute next. The current thread may be selected by the
120 scheduler to keep running. */
121extern void thrd_yield (void);
122
123#ifdef __USE_EXTERN_INLINES
124/* Optimizations. */
125__extern_inline int
126thrd_equal (thrd_t __thread1, thrd_t __thread2)
127{
128 return __thread1 == __thread2;
129}
130#endif
131
132
133/* Mutex functions. */
134
135/* Creates a new mutex object with type __TYPE. If successful the new
136 object is pointed by __MUTEX. */
137extern int mtx_init (mtx_t *__mutex, int __type);
138
139/* Block the current thread until the mutex pointed to by __MUTEX is
140 unlocked. In that case current thread will not be blocked. */
141extern int mtx_lock (mtx_t *__mutex);
142
143/* Block the current thread until the mutex pointed by __MUTEX is unlocked
144 or time pointed by __TIME_POINT is reached. In case the mutex is unlock,
145 the current thread will not be blocked. */
146#ifndef __USE_TIME_BITS64
147extern int mtx_timedlock (mtx_t *__restrict __mutex,
148 const struct timespec *__restrict __time_point);
149#else
150# ifdef __REDIRECT
151extern int __REDIRECT (mtx_timedlock, (mtx_t *__restrict __mutex,
152 const struct timespec *__restrict
153 __time_point),
154 __mtx_timedlock64);
155# else
156# define mtx_timedlock __mtx_timedlock64
157# endif
158#endif
159
160/* Try to lock the mutex pointed by __MUTEX without blocking. If the mutex
161 is free the current threads takes control of it, otherwise it returns
162 immediately. */
163extern int mtx_trylock (mtx_t *__mutex);
164
165/* Unlock the mutex pointed by __MUTEX. It may potentially awake other
166 threads waiting on this mutex. */
167extern int mtx_unlock (mtx_t *__mutex);
168
169/* Destroy the mutex object pointed by __MUTEX. */
170extern void mtx_destroy (mtx_t *__mutex);
171
172
173/* Call function __FUNC exactly once, even if invoked from several threads.
174 All calls must be made with the same __FLAGS object. */
175extern void call_once (once_flag *__flag, void (*__func)(void));
176
177
178/* Condition variable functions. */
179
180/* Initialize new condition variable pointed by __COND. */
181extern int cnd_init (cnd_t *__cond);
182
183/* Unblock one thread that currently waits on condition variable pointed
184 by __COND. */
185extern int cnd_signal (cnd_t *__cond);
186
187/* Unblock all threads currently waiting on condition variable pointed by
188 __COND. */
189extern int cnd_broadcast (cnd_t *__cond);
190
191/* Block current thread on the condition variable pointed by __COND. */
192extern int cnd_wait (cnd_t *__cond, mtx_t *__mutex);
193
194/* Block current thread on the condition variable until condition variable
195 pointed by __COND is signaled or time pointed by __TIME_POINT is
196 reached. */
197#ifndef __USE_TIME_BITS64
198extern int cnd_timedwait (cnd_t *__restrict __cond,
199 mtx_t *__restrict __mutex,
200 const struct timespec *__restrict __time_point);
201#else
202# ifdef __REDIRECT
203extern int __REDIRECT (cnd_timedwait, (cnd_t *__restrict __cond,
204 mtx_t *__restrict __mutex,
205 const struct timespec *__restrict
206 __time_point),
207 __cnd_timedwait64);
208# else
209# define cnd_timedwait __cnd_timedwait64
210# endif
211#endif
212
213/* Destroy condition variable pointed by __cond and free all of its
214 resources. */
215extern void cnd_destroy (cnd_t *__COND);
216
217
218/* Thread specific storage functions. */
219
220/* Create new thread-specific storage key and stores it in the object pointed
221 by __TSS_ID. If __DESTRUCTOR is not NULL, the function will be called when
222 the thread terminates. */
223extern int tss_create (tss_t *__tss_id, tss_dtor_t __destructor);
224
225/* Return the value held in thread-specific storage for the current thread
226 identified by __TSS_ID. */
227extern void *tss_get (tss_t __tss_id);
228
229/* Sets the value of the thread-specific storage identified by __TSS_ID for
230 the current thread to __VAL. */
231extern int tss_set (tss_t __tss_id, void *__val);
232
233/* Destroys the thread-specific storage identified by __TSS_ID. The
234 destructor is not called until thrd_exit is called. */
235extern void tss_delete (tss_t __tss_id);
236
237__END_DECLS
238
239#endif /* _THREADS_H */
240