[userspace-rcu.git] / urcu / lfstack.h

#ifndef _URCU_LFSTACK_H
#define _URCU_LFSTACK_H

/*
 * lfstack.h
 *
 * Userspace RCU library - Lock-Free Stack
 *
 * Copyright 2010-2012 - 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
 */

#ifdef __cplusplus
extern "C" {
#endif

#include <stdbool.h>
#include <pthread.h>

/*
 * Lock-free stack.
 *
 * Stack implementing push, pop, pop_all operations, as well as iterator
 * on the stack head returned by pop_all.
 *
 * Synchronization table:
 *
 * External synchronization techniques described in the API below is
 * required between pairs marked with "X". No external synchronization
 * required between pairs marked with "-".
 *
 *                      cds_lfs_push  __cds_lfs_pop  __cds_lfs_pop_all
 * cds_lfs_push               -              -                  -
 * __cds_lfs_pop              -              X                  X
 * __cds_lfs_pop_all          -              X                  -
 *
 * cds_lfs_pop_blocking and cds_lfs_pop_all_blocking use an internal
 * mutex to provide synchronization.
 */

/*
 * struct cds_lfs_node is returned by cds_lfs_pop, and also used as
 * iterator on stack. It is not safe to dereference the node next
 * pointer when returned by cds_lfs_pop.
 */
struct cds_lfs_node {
	struct cds_lfs_node *next;
};

/*
 * struct cds_lfs_head is returned by __cds_lfs_pop_all, and can be used
 * to begin iteration on the stack. "node" needs to be the first field
 * of cds_lfs_head, so the end-of-stack pointer value can be used for
 * both types.
 */
struct cds_lfs_head {
	struct cds_lfs_node node;
};

struct cds_lfs_stack {
	struct cds_lfs_head *head;
	pthread_mutex_t lock;
};

#ifdef _LGPL_SOURCE

#include <urcu/static/lfstack.h>

#define cds_lfs_node_init		_cds_lfs_node_init
#define cds_lfs_init			_cds_lfs_init
#define cds_lfs_empty			_cds_lfs_empty
#define cds_lfs_push			_cds_lfs_push

/* Locking performed internally */
#define cds_lfs_pop_blocking		_cds_lfs_pop_blocking
#define cds_lfs_pop_all_blocking	_cds_lfs_pop_all_blocking

/* Synchronize pop with internal mutex */
#define cds_lfs_pop_lock		_cds_lfs_pop_lock
#define cds_lfs_pop_unlock		_cds_lfs_pop_unlock

/* Synchronization ensured by the caller. See synchronization table. */
#define __cds_lfs_pop			___cds_lfs_pop
#define __cds_lfs_pop_all		___cds_lfs_pop_all

#else /* !_LGPL_SOURCE */

/*
 * cds_lfs_node_init: initialize lock-free stack node.
 */
extern void cds_lfs_node_init(struct cds_lfs_node *node);

/*
 * cds_lfs_init: initialize lock-free stack.
 */
extern void cds_lfs_init(struct cds_lfs_stack *s);

/*
 * cds_lfs_empty: return whether lock-free stack is empty.
 *
 * No memory barrier is issued. No mutual exclusion is required.
 */
extern bool cds_lfs_empty(struct cds_lfs_stack *s);

/*
 * cds_lfs_push: push a node into the stack.
 *
 * Does not require any synchronization with other push nor pop.
 *
 * Returns 0 if the stack was empty prior to adding the node.
 * Returns non-zero otherwise.
 */
extern bool cds_lfs_push(struct cds_lfs_stack *s,
			struct cds_lfs_node *node);

/*
 * cds_lfs_pop_blocking: pop a node from the stack.
 *
 * Calls __cds_lfs_pop with an internal pop mutex held.
 */
extern struct cds_lfs_node *cds_lfs_pop_blocking(struct cds_lfs_stack *s);

/*
 * cds_lfs_pop_all_blocking: pop all nodes from a stack.
 *
 * Calls __cds_lfs_pop_all with an internal pop mutex held.
 */
extern struct cds_lfs_head *cds_lfs_pop_all_blocking(struct cds_lfs_stack *s);

/*
 * cds_lfs_pop_lock: lock stack pop-protection mutex.
 */
extern void cds_lfs_pop_lock(struct cds_lfs_stack *s);

/*
 * cds_lfs_pop_unlock: unlock stack pop-protection mutex.
 */
extern void cds_lfs_pop_unlock(struct cds_lfs_stack *s);

/*
 * __cds_lfs_pop: pop a node from the stack.
 *
 * Returns NULL if stack is empty.
 *
 * __cds_lfs_pop needs to be synchronized using one of the following
 * techniques:
 *
 * 1) Calling __cds_lfs_pop under rcu read lock critical section. The
 *    caller must wait for a grace period to pass before freeing the
 *    returned node or modifying the cds_lfs_node structure.
 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop
 *    and __cds_lfs_pop_all callers.
 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
 *    __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
 */
extern struct cds_lfs_node *__cds_lfs_pop(struct cds_lfs_stack *s);

/*
 * __cds_lfs_pop_all: pop all nodes from a stack.
 *
 * __cds_lfs_pop_all does not require any synchronization with other
 * push, nor with other __cds_lfs_pop_all, but requires synchronization
 * matching the technique used to synchronize __cds_lfs_pop:
 *
 * 1) If __cds_lfs_pop is called under rcu read lock critical section,
 *    both __cds_lfs_pop and cds_lfs_pop_all callers must wait for a
 *    grace period to pass before freeing the returned node or modifying
 *    the cds_lfs_node structure. However, no RCU read-side critical
 *    section is needed around __cds_lfs_pop_all.
 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and
 *    __cds_lfs_pop_all callers.
 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
 *    __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
 */
extern struct cds_lfs_head *__cds_lfs_pop_all(struct cds_lfs_stack *s);

#endif /* !_LGPL_SOURCE */

/*
 * cds_lfs_for_each: Iterate over all nodes returned by
 *                   __cds_lfs_pop_all.
 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
 * @__node: node to use as iterator (struct cds_lfs_node pointer).
 *
 * Content written into each node before push is guaranteed to be
 * consistent, but no other memory ordering is ensured.
 */
#define cds_lfs_for_each(__head, __node)	\
	for (__node = &__head->node;		\
		__node != NULL;			\
		__node = __node->next)

/*
 * cds_lfs_for_each_safe: Iterate over all nodes returned by
 *                        __cds_lfs_pop_all, safe against node deletion.
 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
 * @__node: node to use as iterator (struct cds_lfs_node pointer).
 * @__n: struct cds_lfs_node pointer holding the next pointer (used
 *       internally).
 *
 * Content written into each node before push is guaranteed to be
 * consistent, but no other memory ordering is ensured.
 */
#define cds_lfs_for_each_safe(__head, __node, __n)			   \
	for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
		__node != NULL;						   \
		__node = __n, __n = (__node ? __node->next : NULL))

#ifdef __cplusplus
}
#endif

#endif /* _URCU_LFSTACK_H */
Commit	Line	Data
	1	#ifndef _URCU_LFSTACK_H
	2	#define _URCU_LFSTACK_H
	3
	4	/*
	5	* lfstack.h
	6	*
	7	* Userspace RCU library - Lock-Free Stack
	8	*
	9	* Copyright 2010-2012 - 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	#ifdef __cplusplus
	27	extern "C" {
	28	#endif
	29
	30	#include <stdbool.h>
	31	#include <pthread.h>
	32
	33	/*
	34	* Lock-free stack.
	35	*
	36	* Stack implementing push, pop, pop_all operations, as well as iterator
	37	* on the stack head returned by pop_all.
	38	*
	39	* Synchronization table:
	40	*
	41	* External synchronization techniques described in the API below is
	42	* required between pairs marked with "X". No external synchronization
	43	* required between pairs marked with "-".
	44	*
	45	* cds_lfs_push __cds_lfs_pop __cds_lfs_pop_all
	46	* cds_lfs_push - - -
	47	* __cds_lfs_pop - X X
	48	* __cds_lfs_pop_all - X -
	49	*
	50	* cds_lfs_pop_blocking and cds_lfs_pop_all_blocking use an internal
	51	* mutex to provide synchronization.
	52	*/
	53
	54	/*
	55	* struct cds_lfs_node is returned by cds_lfs_pop, and also used as
	56	* iterator on stack. It is not safe to dereference the node next
	57	* pointer when returned by cds_lfs_pop.
	58	*/
	59	struct cds_lfs_node {
	60	struct cds_lfs_node *next;
	61	};
	62
	63	/*
	64	* struct cds_lfs_head is returned by __cds_lfs_pop_all, and can be used
	65	* to begin iteration on the stack. "node" needs to be the first field
	66	* of cds_lfs_head, so the end-of-stack pointer value can be used for
	67	* both types.
	68	*/
	69	struct cds_lfs_head {
	70	struct cds_lfs_node node;
	71	};
	72
	73	struct cds_lfs_stack {
	74	struct cds_lfs_head *head;
	75	pthread_mutex_t lock;
	76	};
	77
	78	#ifdef _LGPL_SOURCE
	79
	80	#include <urcu/static/lfstack.h>
	81
	82	#define cds_lfs_node_init _cds_lfs_node_init
	83	#define cds_lfs_init _cds_lfs_init
	84	#define cds_lfs_empty _cds_lfs_empty
	85	#define cds_lfs_push _cds_lfs_push
	86
	87	/* Locking performed internally */
	88	#define cds_lfs_pop_blocking _cds_lfs_pop_blocking
	89	#define cds_lfs_pop_all_blocking _cds_lfs_pop_all_blocking
	90
	91	/* Synchronize pop with internal mutex */
	92	#define cds_lfs_pop_lock _cds_lfs_pop_lock
	93	#define cds_lfs_pop_unlock _cds_lfs_pop_unlock
	94
	95	/* Synchronization ensured by the caller. See synchronization table. */
	96	#define __cds_lfs_pop ___cds_lfs_pop
	97	#define __cds_lfs_pop_all ___cds_lfs_pop_all
	98
	99	#else /* !_LGPL_SOURCE */
	100
	101	/*
	102	* cds_lfs_node_init: initialize lock-free stack node.
	103	*/
	104	extern void cds_lfs_node_init(struct cds_lfs_node *node);
	105
	106	/*
	107	* cds_lfs_init: initialize lock-free stack.
	108	*/
	109	extern void cds_lfs_init(struct cds_lfs_stack *s);
	110
	111	/*
	112	* cds_lfs_empty: return whether lock-free stack is empty.
	113	*
	114	* No memory barrier is issued. No mutual exclusion is required.
	115	*/
	116	extern bool cds_lfs_empty(struct cds_lfs_stack *s);
	117
	118	/*
	119	* cds_lfs_push: push a node into the stack.
	120	*
	121	* Does not require any synchronization with other push nor pop.
	122	*
	123	* Returns 0 if the stack was empty prior to adding the node.
	124	* Returns non-zero otherwise.
	125	*/
	126	extern bool cds_lfs_push(struct cds_lfs_stack *s,
	127	struct cds_lfs_node *node);
	128
	129	/*
	130	* cds_lfs_pop_blocking: pop a node from the stack.
	131	*
	132	* Calls __cds_lfs_pop with an internal pop mutex held.
	133	*/
	134	extern struct cds_lfs_node cds_lfs_pop_blocking(struct cds_lfs_stack s);
	135
	136	/*
	137	* cds_lfs_pop_all_blocking: pop all nodes from a stack.
	138	*
	139	* Calls __cds_lfs_pop_all with an internal pop mutex held.
	140	*/
	141	extern struct cds_lfs_head cds_lfs_pop_all_blocking(struct cds_lfs_stack s);
	142
	143	/*
	144	* cds_lfs_pop_lock: lock stack pop-protection mutex.
	145	*/
	146	extern void cds_lfs_pop_lock(struct cds_lfs_stack *s);
	147
	148	/*
	149	* cds_lfs_pop_unlock: unlock stack pop-protection mutex.
	150	*/
	151	extern void cds_lfs_pop_unlock(struct cds_lfs_stack *s);
	152
	153	/*
	154	* __cds_lfs_pop: pop a node from the stack.
	155	*
	156	* Returns NULL if stack is empty.
	157	*
	158	* __cds_lfs_pop needs to be synchronized using one of the following
	159	* techniques:
	160	*
	161	* 1) Calling __cds_lfs_pop under rcu read lock critical section. The
	162	* caller must wait for a grace period to pass before freeing the
	163	* returned node or modifying the cds_lfs_node structure.
	164	* 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop
	165	* and __cds_lfs_pop_all callers.
	166	* 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
	167	* __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
	168	*/
	169	extern struct cds_lfs_node __cds_lfs_pop(struct cds_lfs_stack s);
	170
	171	/*
	172	* __cds_lfs_pop_all: pop all nodes from a stack.
	173	*
	174	* __cds_lfs_pop_all does not require any synchronization with other
	175	* push, nor with other __cds_lfs_pop_all, but requires synchronization
	176	* matching the technique used to synchronize __cds_lfs_pop:
	177	*
	178	* 1) If __cds_lfs_pop is called under rcu read lock critical section,
	179	* both __cds_lfs_pop and cds_lfs_pop_all callers must wait for a
	180	* grace period to pass before freeing the returned node or modifying
	181	* the cds_lfs_node structure. However, no RCU read-side critical
	182	* section is needed around __cds_lfs_pop_all.
	183	* 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and
	184	* __cds_lfs_pop_all callers.
	185	* 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
	186	* __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
	187	*/
	188	extern struct cds_lfs_head __cds_lfs_pop_all(struct cds_lfs_stack s);
	189
	190	#endif /* !_LGPL_SOURCE */
	191
	192	/*
	193	* cds_lfs_for_each: Iterate over all nodes returned by
	194	* __cds_lfs_pop_all.
	195	* @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
	196	* @__node: node to use as iterator (struct cds_lfs_node pointer).
	197	*
	198	* Content written into each node before push is guaranteed to be
	199	* consistent, but no other memory ordering is ensured.
	200	*/
	201	#define cds_lfs_for_each(__head, __node) \
	202	for (__node = &__head->node; \
	203	__node != NULL; \
	204	__node = __node->next)
	205
	206	/*
	207	* cds_lfs_for_each_safe: Iterate over all nodes returned by
	208	* __cds_lfs_pop_all, safe against node deletion.
	209	* @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
	210	* @__node: node to use as iterator (struct cds_lfs_node pointer).
	211	* @__n: struct cds_lfs_node pointer holding the next pointer (used
	212	* internally).
	213	*
	214	* Content written into each node before push is guaranteed to be
	215	* consistent, but no other memory ordering is ensured.
	216	*/
	217	#define cds_lfs_for_each_safe(__head, __node, __n) \
	218	for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
	219	__node != NULL; \
	220	__node = __n, __n = (__node ? __node->next : NULL))
	221
	222	#ifdef __cplusplus
	223	}
	224	#endif
	225
	226	#endif /* _URCU_LFSTACK_H */