X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=urcu%2Fwfstack.h;h=0890f5c1a54b7d8e590196cf6553ce12f5b7e001;hb=HEAD;hp=b3ee2e7c4585e6e2f735a81ce82b67db3f84a5e2;hpb=cb3f3d6bce4faeb41e4109e12fa722f73a6f6c13;p=userspace-rcu.git diff --git a/urcu/wfstack.h b/urcu/wfstack.h deleted file mode 100644 index b3ee2e7..0000000 --- a/urcu/wfstack.h +++ /dev/null @@ -1,129 +0,0 @@ -#ifndef _URCU_WFSTACK_H -#define _URCU_WFSTACK_H - -/* - * rcuwfstack.h - * - * Userspace RCU library - Stack with Wait-Free push, Blocking pop. - * - * Copyright 2010 - 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 - */ - -#include -#include -#include - -#ifdef __cplusplus -extern "C" { -#endif - -#if (!defined(_GNU_SOURCE) && !defined(_LGPL_SOURCE)) -#error "Dynamic loader LGPL wrappers not implemented yet" -#endif - -#define WF_STACK_END ((void *)0x1UL) -#define WFS_ADAPT_ATTEMPTS 10 /* Retry if being set */ -#define WFS_WAIT 10 /* Wait 10 ms if being set */ - -struct wfs_node { - struct wfs_node *next; -}; - -struct wfs_stack { - struct wfs_node *head; - pthread_mutex_t lock; -}; - -void wfs_node_init(struct wfs_node *node) -{ - node->next = NULL; -} - -void wfs_init(struct wfs_stack *s) -{ - int ret; - - s->head = WF_STACK_END; - ret = pthread_mutex_init(&s->lock, NULL); - assert(!ret); -} - -void wfs_push(struct wfs_stack *s, struct wfs_node *node) -{ - struct wfs_node *old_head; - - assert(node->next == NULL); - /* - * uatomic_xchg() implicit memory barrier orders earlier stores to node - * (setting it to NULL) before publication. - */ - old_head = uatomic_xchg(&s->head, node); - /* - * At this point, dequeuers see a NULL node->next, they should busy-wait - * until node->next is set to old_head. - */ - STORE_SHARED(node->next, old_head); -} - -/* - * Returns NULL if stack is empty. - */ -struct wfs_node * -__wfs_pop_blocking(struct wfs_stack *s) -{ - struct wfs_node *head, *next; - int attempt = 0; - -retry: - head = LOAD_SHARED(s->head); - if (head == WF_STACK_END) - return NULL; - /* - * Adaptative busy-looping waiting for push to complete. - */ - while ((next = LOAD_SHARED(head->next)) == NULL) { - if (++attempt >= WFS_ADAPT_ATTEMPTS) { - poll(NULL, 0, WFS_WAIT); /* Wait for 10ms */ - attempt = 0; - } else - cpu_relax(); - } - if (uatomic_cmpxchg(&s->head, head, next) == head) - return head; - else - goto retry; /* Concurrent modification. Retry. */ -} - -struct wfs_node * -wfs_pop_blocking(struct wfs_stack *s) -{ - struct wfs_node *retnode; - int ret; - - ret = pthread_mutex_lock(&s->lock); - assert(!ret); - retnode = __wfs_pop_blocking(s); - ret = pthread_mutex_unlock(&s->lock); - assert(!ret); - return retnode; -} - -#ifdef __cplusplus -} -#endif - -#endif /* _URCU_WFSTACK_H */