X-Git-Url: https://git.liburcu.org/?p=urcu.git;a=blobdiff_plain;f=urcu%2Frculfqueue-static.h;fp=urcu%2Frculfqueue-static.h;h=0000000000000000000000000000000000000000;hp=410a4cf8d820714dbc88673db078ef89b1545c45;hb=af7c2dbeac32c663b64ad05e4eca70e18784463b;hpb=acfd099eae9026369f558e73b2a7e35860962d9d diff --git a/urcu/rculfqueue-static.h b/urcu/rculfqueue-static.h deleted file mode 100644 index 410a4cf..0000000 --- a/urcu/rculfqueue-static.h +++ /dev/null @@ -1,144 +0,0 @@ -#ifndef _URCU_RCULFQUEUE_STATIC_H -#define _URCU_RCULFQUEUE_STATIC_H - -/* - * rculfqueue-static.h - * - * Userspace RCU library - Lock-Free RCU Queue - * - * Copyright 2010 - Mathieu Desnoyers - * - * TO BE INCLUDED ONLY IN LGPL-COMPATIBLE CODE. See rculfqueue.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 -#include -#include -/* A urcu implementation header should be already included. */ - -#ifdef __cplusplus -extern "C" { -#endif - -/* - * Lock-free RCU queue using reference counting. Enqueue and dequeue operations - * hold a RCU read lock to deal with cmpxchg ABA problem. This implementation - * keeps a dummy head node to ensure we can always update the queue locklessly. - * Given that this is a queue, the dummy head node must always advance as we - * dequeue entries. Therefore, we keep a reference count on each entry we are - * dequeueing, so they can be kept as dummy head node until the next dequeue, at - * which point their reference count will be decremented. - */ - -#define URCU_LFQ_PERMANENT_REF 128 - -void _cds_lfq_node_init_rcu(struct cds_lfq_node_rcu *node) -{ - node->next = NULL; - urcu_ref_init(&node->ref); -} - -void _cds_lfq_init_rcu(struct cds_lfq_queue_rcu *q, - void (*release)(struct urcu_ref *ref)) -{ - _cds_lfq_node_init_rcu(&q->init); - /* Make sure the initial node is never freed. */ - urcu_ref_set(&q->init.ref, URCU_LFQ_PERMANENT_REF); - q->head = q->tail = &q->init; - q->release = release; -} - -/* - * Should be called under rcu read lock critical section. - */ -void _cds_lfq_enqueue_rcu(struct cds_lfq_queue_rcu *q, - struct cds_lfq_node_rcu *node) -{ - urcu_ref_get(&node->ref); - node->queue = q; - - /* - * uatomic_cmpxchg() implicit memory barrier orders earlier stores to - * node before publication. - */ - - for (;;) { - struct cds_lfq_node_rcu *tail, *next; - - tail = rcu_dereference(q->tail); - /* - * Typically expect tail->next to be NULL. - */ - next = uatomic_cmpxchg(&tail->next, NULL, node); - if (next == NULL) { - /* - * Tail was at the end of queue, we successfully - * appended to it. - * Now move tail (another enqueue might beat - * us to it, that's fine). - */ - (void) uatomic_cmpxchg(&q->tail, tail, node); - return; - } else { - /* - * Failure to append to current tail. Help moving tail - * further and retry. - */ - (void) uatomic_cmpxchg(&q->tail, tail, next); - continue; - } - } -} - -/* - * Should be called under rcu read lock critical section. - * - * The entry returned by dequeue must be taken care of by doing a - * sequence of urcu_ref_put which release handler should do a call_rcu. - * - * In other words, the entry lfq node returned by dequeue must not be - * modified/re-used/freed until the reference count reaches zero and a grace - * period has elapsed. - */ -struct cds_lfq_node_rcu *_cds_lfq_dequeue_rcu(struct cds_lfq_queue_rcu *q) -{ - for (;;) { - struct cds_lfq_node_rcu *head, *next; - - head = rcu_dereference(q->head); - next = rcu_dereference(head->next); - if (next) { - if (uatomic_cmpxchg(&q->head, head, next) == head) { - urcu_ref_put(&head->ref, q->release); - return next; - } else { - /* Concurrently pushed, retry */ - continue; - } - } else { - /* Empty */ - return NULL; - } - } -} - -#ifdef __cplusplus -} -#endif - -#endif /* _URCU_RCULFQUEUE_STATIC_H */