[urcu.git] / urcu / tls-compat.h

#ifndef _URCU_TLS_COMPAT_H
#define _URCU_TLS_COMPAT_H

/*
 * urcu/tls-compat.h
 *
 * Userspace RCU library - Thread-Local Storage Compatibility Header
 *
 * Copyright 2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <stdlib.h>
#include <urcu/config.h>
#include <urcu/compiler.h>
#include <urcu/arch.h>

#ifdef __cplusplus
extern "C" {
#endif

#ifdef CONFIG_RCU_TLS	/* Based on ax_tls.m4 */

/*
 * Hint: How to define/declare TLS variables of compound types
 *       such as array or function pointers?
 *
 * Answer: Use typedef to assign a type_name to the compound type.
 * Example: Define a TLS variable which is an int array with len=4:
 *
 * 	typedef int my_int_array_type[4];
 * 	DEFINE_URCU_TLS(my_int_array_type, var_name);
 *
 * Another exmaple:
 * 	typedef void (*call_rcu_flavor)(struct rcu_head *, XXXX);
 * 	DECLARE_URCU_TLS(call_rcu_flavor, p_call_rcu);
 */

# define DECLARE_URCU_TLS(type, name)	\
	CONFIG_RCU_TLS type name

# define DEFINE_URCU_TLS(type, name)	\
	CONFIG_RCU_TLS type name

# define URCU_TLS(name)		(name)

#else /* #ifndef CONFIG_RCU_TLS */

# include <pthread.h>

struct urcu_tls {
	pthread_key_t key;
	pthread_mutex_t init_mutex;
	int init_done;
};

# define DECLARE_URCU_TLS(type, name)				\
	type *__tls_access_ ## name(void)

/*
 * Note: we don't free memory at process exit, since it will be dealt
 * with by the OS.
 */
# define DEFINE_URCU_TLS(type, name)				\
	type *__tls_access_ ## name(void)			\
	{							\
		static struct urcu_tls __tls_ ## name = {	\
			.init_mutex = PTHREAD_MUTEX_INITIALIZER,\
			.init_done = 0,				\
		};						\
		void *__tls_p;					\
		if (!__tls_ ## name.init_done) {		\
			/* Mutex to protect concurrent init */	\
			pthread_mutex_lock(&__tls_ ## name.init_mutex); \
			if (!__tls_ ## name.init_done) {	\
				(void) pthread_key_create(&__tls_ ## name.key, \
					free);			\
				cmm_smp_wmb();	/* create key before write init_done */ \
				__tls_ ## name.init_done = 1;	\
			}					\
			pthread_mutex_unlock(&__tls_ ## name.init_mutex); \
		}						\
		cmm_smp_rmb();	/* read init_done before getting key */ \
		__tls_p = pthread_getspecific(__tls_ ## name.key); \
		if (caa_unlikely(__tls_p == NULL)) {		\
			__tls_p = calloc(1, sizeof(type));	\
			(void) pthread_setspecific(__tls_ ## name.key,	\
				__tls_p);			\
		}						\
		return __tls_p;					\
	}

# define URCU_TLS(name)		(*__tls_access_ ## name())

#endif	/* #else #ifndef CONFIG_RCU_TLS */

#ifdef __cplusplus
}
#endif

#endif /* _URCU_TLS_COMPAT_H */
Commit	Line	Data
	1	#ifndef _URCU_TLS_COMPAT_H
	2	#define _URCU_TLS_COMPAT_H
	3
	4	/*
	5	* urcu/tls-compat.h
	6	*
	7	* Userspace RCU library - Thread-Local Storage Compatibility Header
	8	*
	9	* Copyright 2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	10	*
	11	* This library is free software; you can redistribute it and/or
	12	* modify it under the terms of the GNU Lesser General Public
	13	* License as published by the Free Software Foundation; either
	14	* version 2.1 of the License, or (at your option) any later version.
	15	*
	16	* This library is distributed in the hope that it will be useful,
	17	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	18	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	19	* Lesser General Public License for more details.
	20	*
	21	* You should have received a copy of the GNU Lesser General Public
	22	* License along with this library; if not, write to the Free Software
	23	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	24	*/
	25
	26	#include <stdlib.h>
	27	#include <urcu/config.h>
	28	#include <urcu/compiler.h>
	29	#include <urcu/arch.h>
	30
	31	#ifdef __cplusplus
	32	extern "C" {
	33	#endif
	34
	35	#ifdef CONFIG_RCU_TLS /* Based on ax_tls.m4 */
	36
	37	/*
	38	* Hint: How to define/declare TLS variables of compound types
	39	* such as array or function pointers?
	40	*
	41	* Answer: Use typedef to assign a type_name to the compound type.
	42	* Example: Define a TLS variable which is an int array with len=4:
	43	*
	44	* typedef int my_int_array_type[4];
	45	* DEFINE_URCU_TLS(my_int_array_type, var_name);
	46	*
	47	* Another exmaple:
	48	* typedef void (call_rcu_flavor)(struct rcu_head , XXXX);
	49	* DECLARE_URCU_TLS(call_rcu_flavor, p_call_rcu);
	50	*/
	51
	52	# define DECLARE_URCU_TLS(type, name) \
	53	CONFIG_RCU_TLS type name
	54
	55	# define DEFINE_URCU_TLS(type, name) \
	56	CONFIG_RCU_TLS type name
	57
	58	# define URCU_TLS(name) (name)
	59
	60	#else /* #ifndef CONFIG_RCU_TLS */
	61
	62	# include <pthread.h>
	63
	64	struct urcu_tls {
	65	pthread_key_t key;
	66	pthread_mutex_t init_mutex;
	67	int init_done;
	68	};
	69
	70	# define DECLARE_URCU_TLS(type, name) \
	71	type *__tls_access_ ## name(void)
	72
	73	/*
	74	* Note: we don't free memory at process exit, since it will be dealt
	75	* with by the OS.
	76	*/
	77	# define DEFINE_URCU_TLS(type, name) \
	78	type *__tls_access_ ## name(void) \
	79	{ \
	80	static struct urcu_tls __tls_ ## name = { \
	81	.init_mutex = PTHREAD_MUTEX_INITIALIZER,\
	82	.init_done = 0, \
	83	}; \
	84	void *__tls_p; \
	85	if (!__tls_ ## name.init_done) { \
	86	/* Mutex to protect concurrent init */ \
	87	pthread_mutex_lock(&__tls_ ## name.init_mutex); \
	88	if (!__tls_ ## name.init_done) { \
	89	(void) pthread_key_create(&__tls_ ## name.key, \
	90	free); \
	91	cmm_smp_wmb(); /* create key before write init_done */ \
	92	__tls_ ## name.init_done = 1; \
	93	} \
	94	pthread_mutex_unlock(&__tls_ ## name.init_mutex); \
	95	} \
	96	cmm_smp_rmb(); /* read init_done before getting key */ \
	97	__tls_p = pthread_getspecific(__tls_ ## name.key); \
	98	if (caa_unlikely(__tls_p == NULL)) { \
	99	__tls_p = calloc(1, sizeof(type)); \
	100	(void) pthread_setspecific(__tls_ ## name.key, \
	101	__tls_p); \
	102	} \
	103	return __tls_p; \
	104	}
	105
	106	# define URCU_TLS(name) (*__tls_access_ ## name())
	107
	108	#endif /* #else #ifndef CONFIG_RCU_TLS */
	109
	110	#ifdef __cplusplus
	111	}
	112	#endif
	113
	114	#endif /* _URCU_TLS_COMPAT_H */