[urcu.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;
};

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

/*
 * The transparent union allows calling functions that work on both
 * struct cds_lfs_stack and struct __cds_lfs_stack on any of those two
 * types.
 */
typedef union {
	struct __cds_lfs_stack *_s;
	struct cds_lfs_stack *s;
} __attribute__((__transparent_union__)) cds_lfs_stack_ptr_t;

#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_destroy			_cds_lfs_destroy
#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 (with locking). Pair with
 * cds_lfs_destroy().
 */
extern void cds_lfs_init(struct cds_lfs_stack *s);

/*
 * cds_lfs_destroy: destroy lock-free stack (with lock). Pair with
 * cds_lfs_init().
 */
extern void cds_lfs_destroy(struct cds_lfs_stack *s);

/*
 * __cds_lfs_init: initialize lock-free stack (without lock).
 * Don't pair with any destroy function.
 */
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(cds_lfs_stack_ptr_t 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(cds_lfs_stack_ptr_t 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.
 *    Both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a
 *    grace period to pass before freeing the returned node or pushing
 *    the node back into the stack. It is valid to overwrite the content
 *    of cds_lfs_node immediately after __cds_lfs_pop and
 *    __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_node *__cds_lfs_pop(cds_lfs_stack_ptr_t 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 pushing
 *    the node back into the stack. It is valid to overwrite the content
 *    of cds_lfs_node immediately after __cds_lfs_pop and
 *    __cds_lfs_pop_all. 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(cds_lfs_stack_ptr_t 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
d3bfcb24 MD	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
7294103b MD	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	*/
d3bfcb24 MD	59	struct cds_lfs_node {
	60	struct cds_lfs_node *next;
	61	};
	62
7294103b MD	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
48a8832b MD	73	struct __cds_lfs_stack {
	74	struct cds_lfs_head *head;
	75	};
	76
d3bfcb24	77	struct cds_lfs_stack {
7294103b MD	78	struct cds_lfs_head *head;
7294103b MD	79	pthread_mutex_t lock;
d3bfcb24 MD	80	};
d3bfcb24 MD	81
48a8832b MD	82	/*
	83	* The transparent union allows calling functions that work on both
	84	* struct cds_lfs_stack and struct __cds_lfs_stack on any of those two
	85	* types.
	86	*/
5135c0fd	87	typedef union {
48a8832b MD	88	struct __cds_lfs_stack *_s;
48a8832b MD	89	struct cds_lfs_stack *s;
5135c0fd	90	} __attribute__((__transparent_union__)) cds_lfs_stack_ptr_t;
48a8832b	91
d3bfcb24 MD	92	#ifdef _LGPL_SOURCE
	93
	94	#include <urcu/static/lfstack.h>
	95
	96	#define cds_lfs_node_init _cds_lfs_node_init
	97	#define cds_lfs_init _cds_lfs_init
200d100e	98	#define cds_lfs_destroy _cds_lfs_destroy
817a0178	99	#define __cds_lfs_init ___cds_lfs_init
7294103b	100	#define cds_lfs_empty _cds_lfs_empty
d3bfcb24	101	#define cds_lfs_push _cds_lfs_push
7294103b MD	102
	103	/* Locking performed internally */
	104	#define cds_lfs_pop_blocking _cds_lfs_pop_blocking
	105	#define cds_lfs_pop_all_blocking _cds_lfs_pop_all_blocking
	106
	107	/* Synchronize pop with internal mutex */
	108	#define cds_lfs_pop_lock _cds_lfs_pop_lock
	109	#define cds_lfs_pop_unlock _cds_lfs_pop_unlock
	110
	111	/* Synchronization ensured by the caller. See synchronization table. */
	112	#define __cds_lfs_pop ___cds_lfs_pop
	113	#define __cds_lfs_pop_all ___cds_lfs_pop_all
d3bfcb24 MD	114
	115	#else /* !_LGPL_SOURCE */
	116
7294103b MD	117	/*
	118	* cds_lfs_node_init: initialize lock-free stack node.
	119	*/
d3bfcb24	120	extern void cds_lfs_node_init(struct cds_lfs_node *node);
7294103b MD	121
7294103b MD	122	/*
200d100e MD	123	* cds_lfs_init: initialize lock-free stack (with locking). Pair with
200d100e MD	124	* cds_lfs_destroy().
7294103b	125	*/
d3bfcb24 MD	126	extern void cds_lfs_init(struct cds_lfs_stack *s);
d3bfcb24 MD	127
48a8832b	128	/*
200d100e MD	129	* cds_lfs_destroy: destroy lock-free stack (with lock). Pair with
	130	* cds_lfs_init().
	131	*/
	132	extern void cds_lfs_destroy(struct cds_lfs_stack *s);
	133
	134	/*
	135	* __cds_lfs_init: initialize lock-free stack (without lock).
	136	* Don't pair with any destroy function.
48a8832b MD	137	*/
	138	extern void __cds_lfs_init(struct __cds_lfs_stack *s);
	139
7294103b MD	140	/*
	141	* cds_lfs_empty: return whether lock-free stack is empty.
	142	*
	143	* No memory barrier is issued. No mutual exclusion is required.
	144	*/
48a8832b	145	extern bool cds_lfs_empty(cds_lfs_stack_ptr_t s);
7294103b	146
d3bfcb24 MD	147	/*
	148	* cds_lfs_push: push a node into the stack.
	149	*
	150	* Does not require any synchronization with other push nor pop.
	151	*
	152	* Returns 0 if the stack was empty prior to adding the node.
	153	* Returns non-zero otherwise.
	154	*/
48a8832b	155	extern bool cds_lfs_push(cds_lfs_stack_ptr_t s,
d3bfcb24 MD	156	struct cds_lfs_node *node);
	157
	158	/*
7294103b MD	159	* cds_lfs_pop_blocking: pop a node from the stack.
	160	*
	161	* Calls __cds_lfs_pop with an internal pop mutex held.
	162	*/
	163	extern struct cds_lfs_node cds_lfs_pop_blocking(struct cds_lfs_stack s);
	164
	165	/*
	166	* cds_lfs_pop_all_blocking: pop all nodes from a stack.
	167	*
	168	* Calls __cds_lfs_pop_all with an internal pop mutex held.
	169	*/
	170	extern struct cds_lfs_head cds_lfs_pop_all_blocking(struct cds_lfs_stack s);
	171
	172	/*
	173	* cds_lfs_pop_lock: lock stack pop-protection mutex.
	174	*/
	175	extern void cds_lfs_pop_lock(struct cds_lfs_stack *s);
	176
	177	/*
	178	* cds_lfs_pop_unlock: unlock stack pop-protection mutex.
	179	*/
	180	extern void cds_lfs_pop_unlock(struct cds_lfs_stack *s);
	181
	182	/*
	183	* __cds_lfs_pop: pop a node from the stack.
d3bfcb24 MD	184	*
	185	* Returns NULL if stack is empty.
	186	*
7294103b	187	* __cds_lfs_pop needs to be synchronized using one of the following
d3bfcb24 MD	188	* techniques:
d3bfcb24 MD	189	*
f9b5c2b6 MD	190	* 1) Calling __cds_lfs_pop under rcu read lock critical section.
	191	* Both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a
	192	* grace period to pass before freeing the returned node or pushing
	193	* the node back into the stack. It is valid to overwrite the content
	194	* of cds_lfs_node immediately after __cds_lfs_pop and
	195	* __cds_lfs_pop_all.
7294103b MD	196	* 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop
	197	* and __cds_lfs_pop_all callers.
	198	* 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
	199	* __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
d3bfcb24	200	*/
48a8832b	201	extern struct cds_lfs_node *__cds_lfs_pop(cds_lfs_stack_ptr_t s);
7294103b MD	202
	203	/*
	204	* __cds_lfs_pop_all: pop all nodes from a stack.
	205	*
	206	* __cds_lfs_pop_all does not require any synchronization with other
	207	* push, nor with other __cds_lfs_pop_all, but requires synchronization
	208	* matching the technique used to synchronize __cds_lfs_pop:
	209	*
	210	* 1) If __cds_lfs_pop is called under rcu read lock critical section,
f9b5c2b6 MD	211	* both __cds_lfs_pop and __cds_lfs_pop_all callers must wait for a
	212	* grace period to pass before freeing the returned node or pushing
	213	* the node back into the stack. It is valid to overwrite the content
	214	* of cds_lfs_node immediately after __cds_lfs_pop and
	215	* __cds_lfs_pop_all. No RCU read-side critical section is needed
	216	* around __cds_lfs_pop_all.
7294103b MD	217	* 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and
	218	* __cds_lfs_pop_all callers.
	219	* 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
	220	* __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
	221	*/
48a8832b	222	extern struct cds_lfs_head *__cds_lfs_pop_all(cds_lfs_stack_ptr_t s);
d3bfcb24 MD	223
	224	#endif /* !_LGPL_SOURCE */
	225
7294103b MD	226	/*
	227	* cds_lfs_for_each: Iterate over all nodes returned by
	228	* __cds_lfs_pop_all.
	229	* @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
	230	* @__node: node to use as iterator (struct cds_lfs_node pointer).
	231	*
	232	* Content written into each node before push is guaranteed to be
	233	* consistent, but no other memory ordering is ensured.
	234	*/
	235	#define cds_lfs_for_each(__head, __node) \
	236	for (__node = &__head->node; \
	237	__node != NULL; \
	238	__node = __node->next)
	239
	240	/*
	241	* cds_lfs_for_each_safe: Iterate over all nodes returned by
	242	* __cds_lfs_pop_all, safe against node deletion.
	243	* @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
	244	* @__node: node to use as iterator (struct cds_lfs_node pointer).
	245	* @__n: struct cds_lfs_node pointer holding the next pointer (used
	246	* internally).
	247	*
	248	* Content written into each node before push is guaranteed to be
	249	* consistent, but no other memory ordering is ensured.
	250	*/
	251	#define cds_lfs_for_each_safe(__head, __node, __n) \
	252	for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
	253	__node != NULL; \
	254	__node = __n, __n = (__node ? __node->next : NULL))
	255
d3bfcb24 MD	256	#ifdef __cplusplus
	257	}
	258	#endif
	259
	260	#endif /* _URCU_LFSTACK_H */