-#ifndef _URCU_STATIC_LFSTACK_H
-#define _URCU_STATIC_LFSTACK_H
-
-/*
- * urcu/static/lfstack.h
- *
- * Userspace RCU library - Lock-Free Stack
- *
- * Copyright 2010-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu/lfstack.h for
- * linking dynamically with the userspace rcu library.
- *
- * 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 <stdbool.h>
-#include <pthread.h>
-#include <assert.h>
-#include <urcu/uatomic.h>
-#include <urcu-pointer.h>
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-/*
- * 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.
- */
-
-/*
- * cds_lfs_node_init: initialize lock-free stack node.
- */
-static inline
-void _cds_lfs_node_init(struct cds_lfs_node *node)
-{
-}
-
-/*
- * cds_lfs_init: initialize lock-free stack (with lock). Pair with
- * cds_lfs_destroy().
- */
-static inline
-void _cds_lfs_init(struct cds_lfs_stack *s)
-{
- int ret;
-
- s->head = NULL;
- ret = pthread_mutex_init(&s->lock, NULL);
- assert(!ret);
-}
-
-/*
- * cds_lfs_destroy: destroy lock-free stack (with lock). Pair with
- * cds_lfs_init().
- */
-static inline
-void _cds_lfs_destroy(struct cds_lfs_stack *s)
-{
- int ret = pthread_mutex_destroy(&s->lock);
- assert(!ret);
-}
-
-/*
- * ___cds_lfs_init: initialize lock-free stack (without lock).
- * Don't pair with any destroy function.
- */
-static inline
-void ___cds_lfs_init(struct __cds_lfs_stack *s)
-{
- s->head = NULL;
-}
-
-static inline
-bool ___cds_lfs_empty_head(struct cds_lfs_head *head)
-{
- return head == NULL;
-}
-
-/*
- * cds_lfs_empty: return whether lock-free stack is empty.
- *
- * No memory barrier is issued. No mutual exclusion is required.
- */
-static inline
-bool _cds_lfs_empty(cds_lfs_stack_ptr_t s)
-{
- return ___cds_lfs_empty_head(CMM_LOAD_SHARED(s._s->head));
-}
-
-/*
- * cds_lfs_push: push a node into the stack.
- *
- * Does not require any synchronization with other push nor pop.
- *
- * Lock-free stack push is not subject to ABA problem, so no need to
- * take the RCU read-side lock. Even if "head" changes between two
- * uatomic_cmpxchg() invocations here (being popped, and then pushed
- * again by one or more concurrent threads), the second
- * uatomic_cmpxchg() invocation only cares about pushing a new entry at
- * the head of the stack, ensuring consistency by making sure the new
- * node->next is the same pointer value as the value replaced as head.
- * It does not care about the content of the actual next node, so it can
- * very well be reallocated between the two uatomic_cmpxchg().
- *
- * We take the approach of expecting the stack to be usually empty, so
- * we first try an initial uatomic_cmpxchg() on a NULL old_head, and
- * retry if the old head was non-NULL (the value read by the first
- * uatomic_cmpxchg() is used as old head for the following loop). The
- * upside of this scheme is to minimize the amount of cacheline traffic,
- * always performing an exclusive cacheline access, rather than doing
- * non-exclusive followed by exclusive cacheline access (which would be
- * required if we first read the old head value). This design decision
- * might be revisited after more thorough benchmarking on various
- * platforms.
- *
- * Returns 0 if the stack was empty prior to adding the node.
- * Returns non-zero otherwise.
- */
-static inline
-bool _cds_lfs_push(cds_lfs_stack_ptr_t u_s,
- struct cds_lfs_node *node)
-{
- struct __cds_lfs_stack *s = u_s._s;
- struct cds_lfs_head *head = NULL;
- struct cds_lfs_head *new_head =
- caa_container_of(node, struct cds_lfs_head, node);
-
- for (;;) {
- struct cds_lfs_head *old_head = head;
-
- /*
- * node->next is still private at this point, no need to
- * perform a _CMM_STORE_SHARED().
- */
- node->next = &head->node;
- /*
- * uatomic_cmpxchg() implicit memory barrier orders earlier
- * stores to node before publication.
- */
- head = uatomic_cmpxchg(&s->head, old_head, new_head);
- if (old_head == head)
- break;
- }
- return !___cds_lfs_empty_head(head);
-}
-
-/*
- * __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. 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).
- */
-static inline
-struct cds_lfs_node *___cds_lfs_pop(cds_lfs_stack_ptr_t u_s)
-{
- struct __cds_lfs_stack *s = u_s._s;
-
- for (;;) {
- struct cds_lfs_head *head, *next_head;
- struct cds_lfs_node *next;
-
- head = _CMM_LOAD_SHARED(s->head);
- if (___cds_lfs_empty_head(head))
- return NULL; /* Empty stack */
-
- /*
- * Read head before head->next. Matches the implicit
- * memory barrier before uatomic_cmpxchg() in
- * cds_lfs_push.
- */
- cmm_smp_read_barrier_depends();
- next = _CMM_LOAD_SHARED(head->node.next);
- next_head = caa_container_of(next,
- struct cds_lfs_head, node);
- if (uatomic_cmpxchg(&s->head, head, next_head) == head)
- return &head->node;
- /* busy-loop if head changed under us */
- }
-}
-
-/*
- * __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).
- */
-static inline
-struct cds_lfs_head *___cds_lfs_pop_all(cds_lfs_stack_ptr_t u_s)
-{
- struct __cds_lfs_stack *s = u_s._s;
-
- /*
- * Implicit memory barrier after uatomic_xchg() matches implicit
- * memory barrier before uatomic_cmpxchg() in cds_lfs_push. It
- * ensures that all nodes of the returned list are consistent.
- * There is no need to issue memory barriers when iterating on
- * the returned list, because the full memory barrier issued
- * prior to each uatomic_cmpxchg, which each write to head, are
- * taking care to order writes to each node prior to the full
- * memory barrier after this uatomic_xchg().
- */
- return uatomic_xchg(&s->head, NULL);
-}
-
-/*
- * cds_lfs_pop_lock: lock stack pop-protection mutex.
- */
-static inline void _cds_lfs_pop_lock(struct cds_lfs_stack *s)
-{
- int ret;
-
- ret = pthread_mutex_lock(&s->lock);
- assert(!ret);
-}
-
-/*
- * cds_lfs_pop_unlock: unlock stack pop-protection mutex.
- */
-static inline void _cds_lfs_pop_unlock(struct cds_lfs_stack *s)
-{
- int ret;
-
- ret = pthread_mutex_unlock(&s->lock);
- assert(!ret);
-}
-
-/*
- * Call __cds_lfs_pop with an internal pop mutex held.
- */
-static inline
-struct cds_lfs_node *
-_cds_lfs_pop_blocking(struct cds_lfs_stack *s)
-{
- struct cds_lfs_node *retnode;
-
- _cds_lfs_pop_lock(s);
- retnode = ___cds_lfs_pop(s);
- _cds_lfs_pop_unlock(s);
- return retnode;
-}
-
-/*
- * Call __cds_lfs_pop_all with an internal pop mutex held.
- */
-static inline
-struct cds_lfs_head *
-_cds_lfs_pop_all_blocking(struct cds_lfs_stack *s)
-{
- struct cds_lfs_head *rethead;
-
- _cds_lfs_pop_lock(s);
- rethead = ___cds_lfs_pop_all(s);
- _cds_lfs_pop_unlock(s);
- return rethead;
-}
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* _URCU_STATIC_LFSTACK_H */
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