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/*
* Copyright (C) 2011, 2012 Internet Systems Consortium, Inc. ("ISC")
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
/* $Id$ */
/*
* This is a generic implementation of a two-lock concurrent queue.
* There are built-in mutex locks for the head and tail of the queue,
* allowing elements to be safely added and removed at the same time.
*/
#ifndef ISC_QUEUE_H
#define ISC_QUEUE_H 1
#include <isc/assertions.h>
#include <isc/boolean.h>
#include <isc/mutex.h>
#ifdef ISC_QUEUE_CHECKINIT
#define ISC_QLINK_INSIST(x) ISC_INSIST(x)
#else
#define ISC_QLINK_INSIST(x) (void)0
#endif
#define ISC_QLINK(type) struct { void *next; isc_boolean_t linked; }
#define ISC_QLINK_INIT(elt, link) \
do { \
(elt)->link.next = (void *)(-1); \
(elt)->link.linked = ISC_FALSE; \
} while (0)
#define ISC_QLINK_LINKED(elt, link) ((elt)->link.linked)
#define ISC_QUEUE(type) struct { \
type headnode; \
type *head, *tail; \
isc_mutex_t headlock, taillock; \
}
#define ISC_QUEUE_INIT(queue, link) \
do { \
isc_mutex_init(&(queue).headlock); \
isc_mutex_init(&(queue).taillock); \
(queue).head = (void *) &((queue).headnode); \
(queue).tail = (void *) &((queue).headnode); \
ISC_QLINK_INIT((queue).head, link); \
} while (0)
#define ISC_QUEUE_EMPTY(queue) ISC_TF((queue).head == (queue).tail)
#define ISC_QUEUE_DESTROY(queue) \
do { \
ISC_QLINK_INSIST(ISC_QUEUE_EMPTY(queue)); \
isc_mutex_destroy(&(queue).headlock); \
isc_mutex_destroy(&(queue).taillock); \
} while (0)
#define ISC_QUEUE_PUSH(queue, elt, link) \
do { \
ISC_QLINK_INSIST(!ISC_QLINK_LINKED(elt, link)); \
(elt)->link.next = (void *)(-1); \
LOCK(&(queue).taillock); \
(queue).tail->link.next = elt; \
(queue).tail = elt; \
UNLOCK(&(queue).taillock); \
(elt)->link.linked = ISC_TRUE; \
} while (0)
#define ISC_QUEUE_POP(queue, link, ret) \
do { \
LOCK(&(queue).headlock); \
ret = (queue).head->link.next; \
if (ret == (void *)(-1)) { \
UNLOCK(&(queue).headlock); \
ret = NULL; \
} else { \
(queue).head->link.next = ret->link.next; \
if (ret->link.next == (void *)(-1)) { \
LOCK(&(queue).taillock); \
(queue).tail = (queue).head; \
UNLOCK(&(queue).taillock); \
} \
UNLOCK(&(queue).headlock); \
ret->link.next = (void *)(-1); \
ret->link.linked = ISC_FALSE; \
} \
} while (0)
#endif /* ISC_QUEUE_H */
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