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100 lines
3 KiB
C
100 lines
3 KiB
C
/*
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* Copyright (C) 2011 Internet Systems Consortium, Inc. ("ISC")
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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/* $Id: queue.h,v 1.2 2011/10/10 22:57:13 each Exp $ */
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/*
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* This is a generic implementation of a two-lock concurrent queue.
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* There are built-in mutex locks for the head and tail of the queue,
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* allowing elements to be safely added and removed at the same time.
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*/
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#ifndef ISC_QUEUE_H
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#define ISC_QUEUE_H 1
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#include <isc/assertions.h>
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#include <isc/boolean.h>
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#include <isc/mutex.h>
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#ifdef ISC_QUEUE_CHECKINIT
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#define ISC_QLINK_INSIST(x) ISC_INSIST(x)
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#else
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#define ISC_QLINK_INSIST(x) (void)0
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#endif
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#define ISC_QLINK(type) struct { void *next; isc_boolean_t linked; }
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#define ISC_QLINK_INIT(elt, link) \
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do { \
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(elt)->link.next = (void *)(-1); \
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(elt)->link.linked = ISC_FALSE; \
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} while (0)
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#define ISC_QLINK_LINKED(elt, link) ((elt)->link.linked)
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#define ISC_QUEUE(type) struct { \
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type headnode; \
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type *head, *tail; \
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isc_mutex_t headlock, taillock; \
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}
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#define ISC_QUEUE_INIT(queue, link) \
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do { \
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isc_mutex_init(&(queue).headlock); \
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isc_mutex_init(&(queue).taillock); \
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(queue).head = (void *) &((queue).headnode); \
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(queue).tail = (void *) &((queue).headnode); \
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ISC_QLINK_INIT((queue).head, link); \
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} while (0)
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#define ISC_QUEUE_EMPTY(queue) ISC_TF((queue).head == (queue).tail)
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#define ISC_QUEUE_DESTROY(queue) \
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do { \
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ISC_QLINK_INSIST(ISC_QUEUE_EMPTY(queue)); \
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isc_mutex_destroy(&(queue).headlock); \
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isc_mutex_destroy(&(queue).taillock); \
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} while (0)
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#define ISC_QUEUE_PUSH(queue, elt, link) \
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do { \
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ISC_QLINK_INSIST(!ISC_QLINK_LINKED(elt, link)); \
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(elt)->link.next = (void *)(-1); \
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LOCK(&(queue).taillock); \
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(queue).tail->link.next = elt; \
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(queue).tail = elt; \
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UNLOCK(&(queue).taillock); \
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(elt)->link.linked = ISC_TRUE; \
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} while (0)
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#define ISC_QUEUE_POP(queue, link, ret) \
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do { \
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LOCK(&(queue).headlock); \
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ret = (queue).head->link.next; \
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if (ret == (void *)(-1)) { \
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UNLOCK(&(queue).headlock); \
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ret = NULL; \
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} else { \
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(queue).head->link.next = ret->link.next; \
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if (ret->link.next == (void *)(-1)) { \
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LOCK(&(queue).taillock); \
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(queue).tail = (queue).head; \
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UNLOCK(&(queue).taillock); \
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} \
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UNLOCK(&(queue).headlock); \
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ret->link.next = (void *)(-1); \
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ret->link.linked = ISC_FALSE; \
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} \
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} while (0)
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#endif /* ISC_QUEUE_H */
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