#ifndef _URCU_LFSTACK_H #define _URCU_LFSTACK_H /* * lfstack.h * * Userspace RCU library - Lock-Free Stack * * Copyright 2010-2012 - Mathieu Desnoyers * * 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 #include /* * 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 #define cds_lfs_node_init _cds_lfs_node_init #define cds_lfs_init _cds_lfs_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 */