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/* Thread-local storage in multithreaded situations.
Copyright (C) 2005, 2007-2020 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2005. */
/* This file contains thread-local storage primitives for use with a given
thread library. It does not contain primitives for creating threads or
for other multithreading primitives.
Type: gl_tls_key_t
Initialization: gl_tls_key_init (name, destructor);
Getting per-thread value: gl_tls_get (name)
Setting per-thread value: gl_tls_set (name, pointer);
De-initialization: gl_tls_key_destroy (name);
Equivalent functions with control of error handling:
Initialization: err = glthread_tls_key_init (&name, destructor);
Setting per-thread value: err = glthread_tls_set (&name, pointer);
De-initialization: err = glthread_tls_key_destroy (&name);
A per-thread value is of type 'void *'.
A destructor is a function pointer of type 'void (*) (void *)', called
when a thread exits, and taking the last per-thread value as argument. It
is unspecified whether the destructor function is called when the last
per-thread value is NULL. On some platforms, the destructor function is
not called at all.
*/
#ifndef _TLS_H
#define _TLS_H
#include <errno.h>
#include <stdlib.h>
#if !defined c11_threads_in_use
# if HAVE_THREADS_H && USE_POSIX_THREADS_WEAK
# include <threads.h>
# pragma weak thrd_exit
# define c11_threads_in_use() (thrd_exit != NULL)
# else
# define c11_threads_in_use() 0
# endif
#endif
/* ========================================================================= */
#if USE_ISOC_THREADS || USE_ISOC_AND_POSIX_THREADS
/* Use the ISO C threads library. */
# include <threads.h>
/* ------------------------- gl_tls_key_t datatype ------------------------- */
typedef tss_t gl_tls_key_t;
# define glthread_tls_key_init(KEY, DESTRUCTOR) \
(tss_create (KEY, DESTRUCTOR) != thrd_success ? EAGAIN : 0)
# define gl_tls_get(NAME) \
tss_get (NAME)
# define glthread_tls_set(KEY, POINTER) \
(tss_set (*(KEY), (POINTER)) != thrd_success ? ENOMEM : 0)
# define glthread_tls_key_destroy(KEY) \
(tss_delete (*(KEY)), 0)
#endif
/* ========================================================================= */
#if USE_POSIX_THREADS
/* Use the POSIX threads library. */
# include <pthread.h>
# if PTHREAD_IN_USE_DETECTION_HARD
/* The pthread_in_use() detection needs to be done at runtime. */
# define pthread_in_use() \
glthread_in_use ()
extern int glthread_in_use (void);
# endif
# if USE_POSIX_THREADS_WEAK
/* Use weak references to the POSIX threads library. */
# pragma weak pthread_key_create
# pragma weak pthread_getspecific
# pragma weak pthread_setspecific
# pragma weak pthread_key_delete
# ifndef pthread_self
# pragma weak pthread_self
# endif
# if !PTHREAD_IN_USE_DETECTION_HARD
# pragma weak pthread_mutexattr_gettype
# define pthread_in_use() \
(pthread_mutexattr_gettype != NULL || c11_threads_in_use ())
# endif
# else
# if !PTHREAD_IN_USE_DETECTION_HARD
# define pthread_in_use() 1
# endif
# endif
/* ------------------------- gl_tls_key_t datatype ------------------------- */
typedef union
{
void *singlethread_value;
pthread_key_t key;
}
gl_tls_key_t;
# define glthread_tls_key_init(KEY, DESTRUCTOR) \
(pthread_in_use () \
? pthread_key_create (&(KEY)->key, DESTRUCTOR) \
: ((KEY)->singlethread_value = NULL, 0))
# define gl_tls_get(NAME) \
(pthread_in_use () \
? pthread_getspecific ((NAME).key) \
: (NAME).singlethread_value)
# define glthread_tls_set(KEY, POINTER) \
(pthread_in_use () \
? pthread_setspecific ((KEY)->key, (POINTER)) \
: ((KEY)->singlethread_value = (POINTER), 0))
# define glthread_tls_key_destroy(KEY) \
(pthread_in_use () ? pthread_key_delete ((KEY)->key) : 0)
#endif
/* ========================================================================= */
#if USE_WINDOWS_THREADS
# define WIN32_LEAN_AND_MEAN /* avoid including junk */
# include <windows.h>
# include "windows-tls.h"
/* ------------------------- gl_tls_key_t datatype ------------------------- */
typedef glwthread_tls_key_t gl_tls_key_t;
# define glthread_tls_key_init(KEY, DESTRUCTOR) \
glwthread_tls_key_create (KEY, DESTRUCTOR)
# define gl_tls_get(NAME) \
TlsGetValue (NAME)
# define glthread_tls_set(KEY, POINTER) \
(!TlsSetValue (*(KEY), POINTER) ? EINVAL : 0)
# define glthread_tls_key_destroy(KEY) \
glwthread_tls_key_delete (*(KEY))
#endif
/* ========================================================================= */
#if !(USE_ISOC_THREADS || USE_POSIX_THREADS || USE_ISOC_AND_POSIX_THREADS || USE_WINDOWS_THREADS)
/* Provide dummy implementation if threads are not supported. */
/* ------------------------- gl_tls_key_t datatype ------------------------- */
typedef struct
{
void *singlethread_value;
}
gl_tls_key_t;
# define glthread_tls_key_init(KEY, DESTRUCTOR) \
((KEY)->singlethread_value = NULL, \
(void) (DESTRUCTOR), \
0)
# define gl_tls_get(NAME) \
(NAME).singlethread_value
# define glthread_tls_set(KEY, POINTER) \
((KEY)->singlethread_value = (POINTER), 0)
# define glthread_tls_key_destroy(KEY) \
0
#endif
/* ========================================================================= */
/* Macros with built-in error handling. */
/* ------------------------- gl_tls_key_t datatype ------------------------- */
#define gl_tls_key_init(NAME, DESTRUCTOR) \
do \
{ \
if (glthread_tls_key_init (&NAME, DESTRUCTOR)) \
abort (); \
} \
while (0)
#define gl_tls_set(NAME, POINTER) \
do \
{ \
if (glthread_tls_set (&NAME, POINTER)) \
abort (); \
} \
while (0)
#define gl_tls_key_destroy(NAME) \
do \
{ \
if (glthread_tls_key_destroy (&NAME)) \
abort (); \
} \
while (0)
/* ========================================================================= */
#endif /* _TLS_H */
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