+++ /dev/null
-#ifndef _URCU_STATIC_WFSTACK_H
-#define _URCU_STATIC_WFSTACK_H
-
-/*
- * urcu/static/wfstack.h
- *
- * Userspace RCU library - Stack with with wait-free push, blocking traversal.
- *
- * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See urcu/wfstack.h for
- * linking dynamically with the userspace rcu library.
- *
- * 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
- */
-
-#include <pthread.h>
-#include <assert.h>
-#include <poll.h>
-#include <stdbool.h>
-#include <urcu/compiler.h>
-#include <urcu/uatomic.h>
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#define CDS_WFS_END ((void *) 0x1UL)
-#define CDS_WFS_ADAPT_ATTEMPTS 10 /* Retry if being set */
-#define CDS_WFS_WAIT 10 /* Wait 10 ms if being set */
-
-/*
- * Stack with wait-free push, blocking traversal.
- *
- * Stack implementing push, pop, pop_all operations, as well as iterator
- * on the stack head returned by pop_all.
- *
- * Wait-free operations: cds_wfs_push, __cds_wfs_pop_all, cds_wfs_empty,
- * cds_wfs_first.
- * Blocking operations: cds_wfs_pop, cds_wfs_pop_all, cds_wfs_next,
- * iteration on 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_wfs_push __cds_wfs_pop __cds_wfs_pop_all
- * cds_wfs_push - - -
- * __cds_wfs_pop - X X
- * __cds_wfs_pop_all - X -
- *
- * cds_wfs_pop and cds_wfs_pop_all use an internal mutex to provide
- * synchronization.
- */
-
-/*
- * cds_wfs_node_init: initialize wait-free stack node.
- */
-static inline
-void _cds_wfs_node_init(struct cds_wfs_node *node)
-{
- node->next = NULL;
-}
-
-/*
- * __cds_wfs_init: initialize wait-free stack. Don't pair with
- * any destroy function.
- */
-static inline void ___cds_wfs_init(struct __cds_wfs_stack *s)
-{
- s->head = CDS_WFS_END;
-}
-
-/*
- * cds_wfs_init: initialize wait-free stack. Pair with
- * cds_wfs_destroy().
- */
-static inline
-void _cds_wfs_init(struct cds_wfs_stack *s)
-{
- int ret;
-
- s->head = CDS_WFS_END;
- ret = pthread_mutex_init(&s->lock, NULL);
- assert(!ret);
-}
-
-/*
- * cds_wfs_destroy: destroy wait-free stack. Pair with
- * cds_wfs_init().
- */
-static inline
-void _cds_wfs_destroy(struct cds_wfs_stack *s)
-{
- int ret = pthread_mutex_destroy(&s->lock);
- assert(!ret);
-}
-
-static inline bool ___cds_wfs_end(void *node)
-{
- return node == CDS_WFS_END;
-}
-
-/*
- * cds_wfs_empty: return whether wait-free stack is empty.
- *
- * No memory barrier is issued. No mutual exclusion is required.
- */
-static inline bool _cds_wfs_empty(cds_wfs_stack_ptr_t u_stack)
-{
- struct __cds_wfs_stack *s = u_stack._s;
-
- return ___cds_wfs_end(CMM_LOAD_SHARED(s->head));
-}
-
-/*
- * cds_wfs_push: push a node into the stack.
- *
- * Issues a full memory barrier before push. No mutual exclusion is
- * required.
- *
- * Returns 0 if the stack was empty prior to adding the node.
- * Returns non-zero otherwise.
- */
-static inline
-int _cds_wfs_push(cds_wfs_stack_ptr_t u_stack, struct cds_wfs_node *node)
-{
- struct __cds_wfs_stack *s = u_stack._s;
- struct cds_wfs_head *old_head, *new_head;
-
- assert(node->next == NULL);
- new_head = caa_container_of(node, struct cds_wfs_head, node);
- /*
- * uatomic_xchg() implicit memory barrier orders earlier stores
- * to node (setting it to NULL) before publication.
- */
- old_head = uatomic_xchg(&s->head, new_head);
- /*
- * At this point, dequeuers see a NULL node->next, they should
- * busy-wait until node->next is set to old_head.
- */
- CMM_STORE_SHARED(node->next, &old_head->node);
- return !___cds_wfs_end(old_head);
-}
-
-/*
- * Waiting for push to complete enqueue and return the next node.
- */
-static inline struct cds_wfs_node *
-___cds_wfs_node_sync_next(struct cds_wfs_node *node, int blocking)
-{
- struct cds_wfs_node *next;
- int attempt = 0;
-
- /*
- * Adaptative busy-looping waiting for push to complete.
- */
- while ((next = CMM_LOAD_SHARED(node->next)) == NULL) {
- if (!blocking)
- return CDS_WFS_WOULDBLOCK;
- if (++attempt >= CDS_WFS_ADAPT_ATTEMPTS) {
- (void) poll(NULL, 0, CDS_WFS_WAIT); /* Wait for 10ms */
- attempt = 0;
- } else {
- caa_cpu_relax();
- }
- }
-
- return next;
-}
-
-static inline
-struct cds_wfs_node *
-___cds_wfs_pop(cds_wfs_stack_ptr_t u_stack, int *state, int blocking)
-{
- struct cds_wfs_head *head, *new_head;
- struct cds_wfs_node *next;
- struct __cds_wfs_stack *s = u_stack._s;
-
- if (state)
- *state = 0;
- for (;;) {
- head = CMM_LOAD_SHARED(s->head);
- if (___cds_wfs_end(head)) {
- return NULL;
- }
- next = ___cds_wfs_node_sync_next(&head->node, blocking);
- if (!blocking && next == CDS_WFS_WOULDBLOCK) {
- return CDS_WFS_WOULDBLOCK;
- }
- new_head = caa_container_of(next, struct cds_wfs_head, node);
- if (uatomic_cmpxchg(&s->head, head, new_head) == head) {
- if (state && ___cds_wfs_end(new_head))
- *state |= CDS_WFS_STATE_LAST;
- return &head->node;
- }
- if (!blocking) {
- return CDS_WFS_WOULDBLOCK;
- }
- /* busy-loop if head changed under us */
- }
-}
-
-/*
- * __cds_wfs_pop_with_state_blocking: pop a node from the stack, with state.
- *
- * Returns NULL if stack is empty.
- *
- * __cds_wfs_pop_blocking needs to be synchronized using one of the
- * following techniques:
- *
- * 1) Calling __cds_wfs_pop_blocking 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_wfs_node structure.
- * 2) Using mutual exclusion (e.g. mutexes) to protect
- * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers.
- * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking()
- * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme).
- *
- * "state" saves state flags atomically sampled with pop operation.
- */
-static inline
-struct cds_wfs_node *
-___cds_wfs_pop_with_state_blocking(cds_wfs_stack_ptr_t u_stack, int *state)
-{
- return ___cds_wfs_pop(u_stack, state, 1);
-}
-
-static inline
-struct cds_wfs_node *
-___cds_wfs_pop_blocking(cds_wfs_stack_ptr_t u_stack)
-{
- return ___cds_wfs_pop_with_state_blocking(u_stack, NULL);
-}
-
-/*
- * __cds_wfs_pop_with_state_nonblocking: pop a node from the stack.
- *
- * Same as __cds_wfs_pop_with_state_blocking, but returns
- * CDS_WFS_WOULDBLOCK if it needs to block.
- *
- * "state" saves state flags atomically sampled with pop operation.
- */
-static inline
-struct cds_wfs_node *
-___cds_wfs_pop_with_state_nonblocking(cds_wfs_stack_ptr_t u_stack, int *state)
-{
- return ___cds_wfs_pop(u_stack, state, 0);
-}
-
-/*
- * __cds_wfs_pop_nonblocking: pop a node from the stack.
- *
- * Same as __cds_wfs_pop_blocking, but returns CDS_WFS_WOULDBLOCK if
- * it needs to block.
- */
-static inline
-struct cds_wfs_node *
-___cds_wfs_pop_nonblocking(cds_wfs_stack_ptr_t u_stack)
-{
- return ___cds_wfs_pop_with_state_nonblocking(u_stack, NULL);
-}
-
-/*
- * __cds_wfs_pop_all: pop all nodes from a stack.
- *
- * __cds_wfs_pop_all does not require any synchronization with other
- * push, nor with other __cds_wfs_pop_all, but requires synchronization
- * matching the technique used to synchronize __cds_wfs_pop_blocking:
- *
- * 1) If __cds_wfs_pop_blocking is called under rcu read lock critical
- * section, both __cds_wfs_pop_blocking and cds_wfs_pop_all callers
- * must wait for a grace period to pass before freeing the returned
- * node or modifying the cds_wfs_node structure. However, no RCU
- * read-side critical section is needed around __cds_wfs_pop_all.
- * 2) Using mutual exclusion (e.g. mutexes) to protect
- * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers.
- * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking()
- * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme).
- */
-static inline
-struct cds_wfs_head *
-___cds_wfs_pop_all(cds_wfs_stack_ptr_t u_stack)
-{
- struct __cds_wfs_stack *s = u_stack._s;
- struct cds_wfs_head *head;
-
- /*
- * Implicit memory barrier after uatomic_xchg() matches implicit
- * memory barrier before uatomic_xchg() in cds_wfs_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().
- */
- head = uatomic_xchg(&s->head, CDS_WFS_END);
- if (___cds_wfs_end(head))
- return NULL;
- return head;
-}
-
-/*
- * cds_wfs_pop_lock: lock stack pop-protection mutex.
- */
-static inline void _cds_wfs_pop_lock(struct cds_wfs_stack *s)
-{
- int ret;
-
- ret = pthread_mutex_lock(&s->lock);
- assert(!ret);
-}
-
-/*
- * cds_wfs_pop_unlock: unlock stack pop-protection mutex.
- */
-static inline void _cds_wfs_pop_unlock(struct cds_wfs_stack *s)
-{
- int ret;
-
- ret = pthread_mutex_unlock(&s->lock);
- assert(!ret);
-}
-
-/*
- * Call __cds_wfs_pop_with_state_blocking with an internal pop mutex held.
- */
-static inline
-struct cds_wfs_node *
-_cds_wfs_pop_with_state_blocking(struct cds_wfs_stack *s, int *state)
-{
- struct cds_wfs_node *retnode;
-
- _cds_wfs_pop_lock(s);
- retnode = ___cds_wfs_pop_with_state_blocking(s, state);
- _cds_wfs_pop_unlock(s);
- return retnode;
-}
-
-/*
- * Call _cds_wfs_pop_with_state_blocking without saving any state.
- */
-static inline
-struct cds_wfs_node *
-_cds_wfs_pop_blocking(struct cds_wfs_stack *s)
-{
- return _cds_wfs_pop_with_state_blocking(s, NULL);
-}
-
-/*
- * Call __cds_wfs_pop_all with an internal pop mutex held.
- */
-static inline
-struct cds_wfs_head *
-_cds_wfs_pop_all_blocking(struct cds_wfs_stack *s)
-{
- struct cds_wfs_head *rethead;
-
- _cds_wfs_pop_lock(s);
- rethead = ___cds_wfs_pop_all(s);
- _cds_wfs_pop_unlock(s);
- return rethead;
-}
-
-/*
- * cds_wfs_first: get first node of a popped stack.
- *
- * Content written into the node before enqueue is guaranteed to be
- * consistent, but no other memory ordering is ensured.
- *
- * Used by for-like iteration macros in urcu/wfstack.h:
- * cds_wfs_for_each_blocking()
- * cds_wfs_for_each_blocking_safe()
- *
- * Returns NULL if popped stack is empty, top stack node otherwise.
- */
-static inline struct cds_wfs_node *
-_cds_wfs_first(struct cds_wfs_head *head)
-{
- if (___cds_wfs_end(head))
- return NULL;
- return &head->node;
-}
-
-static inline struct cds_wfs_node *
-___cds_wfs_next(struct cds_wfs_node *node, int blocking)
-{
- struct cds_wfs_node *next;
-
- next = ___cds_wfs_node_sync_next(node, blocking);
- /*
- * CDS_WFS_WOULDBLOCK != CSD_WFS_END, so we can check for end
- * even if ___cds_wfs_node_sync_next returns CDS_WFS_WOULDBLOCK,
- * and still return CDS_WFS_WOULDBLOCK.
- */
- if (___cds_wfs_end(next))
- return NULL;
- return next;
-}
-
-/*
- * cds_wfs_next_blocking: get next node of a popped stack.
- *
- * Content written into the node before enqueue is guaranteed to be
- * consistent, but no other memory ordering is ensured.
- *
- * Used by for-like iteration macros in urcu/wfstack.h:
- * cds_wfs_for_each_blocking()
- * cds_wfs_for_each_blocking_safe()
- *
- * Returns NULL if reached end of popped stack, non-NULL next stack
- * node otherwise.
- */
-static inline struct cds_wfs_node *
-_cds_wfs_next_blocking(struct cds_wfs_node *node)
-{
- return ___cds_wfs_next(node, 1);
-}
-
-
-/*
- * cds_wfs_next_nonblocking: get next node of a popped stack.
- *
- * Same as cds_wfs_next_blocking, but returns CDS_WFS_WOULDBLOCK if it
- * needs to block.
- */
-static inline struct cds_wfs_node *
-_cds_wfs_next_nonblocking(struct cds_wfs_node *node)
-{
- return ___cds_wfs_next(node, 0);
-}
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* _URCU_STATIC_WFSTACK_H */
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