1 /* 2 * Copyright (C) 2011, 2012 Internet Systems Consortium, Inc. ("ISC") 3 * 4 * Permission to use, copy, modify, and/or distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 9 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 10 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 11 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 12 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 13 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 14 * PERFORMANCE OF THIS SOFTWARE. 15 */ 16 17 /* $Id$ */ 18 19 /* 20 * This is a generic implementation of a two-lock concurrent queue. 21 * There are built-in mutex locks for the head and tail of the queue, 22 * allowing elements to be safely added and removed at the same time. 23 */ 24 25 #ifndef ISC_QUEUE_H 26 #define ISC_QUEUE_H 1 27 #include <isc/assertions.h> 28 #include <isc/boolean.h> 29 #include <isc/mutex.h> 30 31 #ifdef ISC_QUEUE_CHECKINIT 32 #define ISC_QLINK_INSIST(x) ISC_INSIST(x) 33 #else 34 #define ISC_QLINK_INSIST(x) (void)0 35 #endif 36 37 #define ISC_QLINK(type) struct { void *next; isc_boolean_t linked; } 38 #define ISC_QLINK_INIT(elt, link) \ 39 do { \ 40 (elt)->link.next = (void *)(-1); \ 41 (elt)->link.linked = ISC_FALSE; \ 42 } while (0) 43 #define ISC_QLINK_LINKED(elt, link) ((elt)->link.linked) 44 45 #define ISC_QUEUE(type) struct { \ 46 type headnode; \ 47 type *head, *tail; \ 48 isc_mutex_t headlock, taillock; \ 49 } 50 51 #define ISC_QUEUE_INIT(queue, link) \ 52 do { \ 53 isc_mutex_init(&(queue).headlock); \ 54 isc_mutex_init(&(queue).taillock); \ 55 (queue).head = (void *) &((queue).headnode); \ 56 (queue).tail = (void *) &((queue).headnode); \ 57 ISC_QLINK_INIT((queue).head, link); \ 58 } while (0) 59 60 #define ISC_QUEUE_EMPTY(queue) ISC_TF((queue).head == (queue).tail) 61 62 #define ISC_QUEUE_DESTROY(queue) \ 63 do { \ 64 ISC_QLINK_INSIST(ISC_QUEUE_EMPTY(queue)); \ 65 isc_mutex_destroy(&(queue).headlock); \ 66 isc_mutex_destroy(&(queue).taillock); \ 67 } while (0) 68 69 #define ISC_QUEUE_PUSH(queue, elt, link) \ 70 do { \ 71 ISC_QLINK_INSIST(!ISC_QLINK_LINKED(elt, link)); \ 72 (elt)->link.next = (void *)(-1); \ 73 LOCK(&(queue).taillock); \ 74 (queue).tail->link.next = elt; \ 75 (queue).tail = elt; \ 76 UNLOCK(&(queue).taillock); \ 77 (elt)->link.linked = ISC_TRUE; \ 78 } while (0) 79 80 #define ISC_QUEUE_POP(queue, link, ret) \ 81 do { \ 82 LOCK(&(queue).headlock); \ 83 ret = (queue).head->link.next; \ 84 if (ret == (void *)(-1)) { \ 85 UNLOCK(&(queue).headlock); \ 86 ret = NULL; \ 87 } else { \ 88 (queue).head->link.next = ret->link.next; \ 89 if (ret->link.next == (void *)(-1)) { \ 90 LOCK(&(queue).taillock); \ 91 (queue).tail = (queue).head; \ 92 UNLOCK(&(queue).taillock); \ 93 } \ 94 UNLOCK(&(queue).headlock); \ 95 ret->link.next = (void *)(-1); \ 96 ret->link.linked = ISC_FALSE; \ 97 } \ 98 } while (0) 99 100 #endif /* ISC_QUEUE_H */ 101