xref: /netbsd/lib/libpthread/pthread_queue.h (revision abd1934e)
1 /*	$NetBSD: pthread_queue.h,v 1.7 2022/04/19 20:32:17 rillig Exp $	*/
2 
3 /*-
4  * Copyright (c) 2001 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Nathan J. Williams.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #ifndef _LIB_PTHREAD_QUEUE_H
33 #define _LIB_PTHREAD_QUEUE_H
34 
35 /*
36  * Definition of a queue interface for the pthread library.
37  * Style modeled on the sys/queue.h macros; implementation taken from
38  * the tail queue, with the added property of static initializability
39  * (and a corresponding extra cost in the _INSERT_TAIL() function.
40 */
41 
42 /*
43  * Queue definitions.
44  */
45 
46 #define PTQ_HEAD(name, type)						\
47 struct name {								\
48 	struct type *ptqh_first;/* first element */			\
49 	struct type **ptqh_last;/* addr of last next element */		\
50 }
51 
52 #define PTQ_HEAD_INITIALIZER { NULL, NULL }
53 
54 #define PTQ_ENTRY(type)							\
55 struct {								\
56 	struct type *ptqe_next;	/* next element */			\
57 	struct type **ptqe_prev;/* address of previous next element */	\
58 }
59 
60 /*
61  * Queue functions.
62  */
63 
64 #define	PTQ_INIT(head) do {						\
65 	(head)->ptqh_first = NULL;					\
66 	(head)->ptqh_last = &(head)->ptqh_first;			\
67 } while (0)
68 
69 #define	PTQ_INSERT_HEAD(head, elm, field) do {				\
70 	if (((elm)->field.ptqe_next = (head)->ptqh_first) != NULL)	\
71 		(head)->ptqh_first->field.ptqe_prev =			\
72 		    &(elm)->field.ptqe_next;				\
73 	else								\
74 		(head)->ptqh_last = &(elm)->field.ptqe_next;		\
75 	(head)->ptqh_first = (elm);					\
76 	(elm)->field.ptqe_prev = &(head)->ptqh_first;			\
77 } while (0)
78 
79 #define	PTQ_INSERT_TAIL(head, elm, field) do {				\
80 	(elm)->field.ptqe_next = NULL;					\
81 	if ((head)->ptqh_last == NULL)					\
82 		(head)->ptqh_last = &(head)->ptqh_first;		\
83 	(elm)->field.ptqe_prev = (head)->ptqh_last;			\
84 	*(head)->ptqh_last = (elm);					\
85 	(head)->ptqh_last = &(elm)->field.ptqe_next;			\
86 } while (0)
87 
88 #define	PTQ_INSERT_AFTER(head, listelm, elm, field) do {		\
89 	if (((elm)->field.ptqe_next = (listelm)->field.ptqe_next) != NULL)\
90 		(elm)->field.ptqe_next->field.ptqe_prev = 		\
91 		    &(elm)->field.ptqe_next;				\
92 	else								\
93 		(head)->ptqh_last = &(elm)->field.ptqe_next;		\
94 	(listelm)->field.ptqe_next = (elm);				\
95 	(elm)->field.ptqe_prev = &(listelm)->field.ptqe_next;		\
96 } while (0)
97 
98 #define	PTQ_INSERT_BEFORE(listelm, elm, field) do {			\
99 	(elm)->field.ptqe_prev = (listelm)->field.ptqe_prev;		\
100 	(elm)->field.ptqe_next = (listelm);				\
101 	*(listelm)->field.ptqe_prev = (elm);				\
102 	(listelm)->field.ptqe_prev = &(elm)->field.ptqe_next;		\
103 } while (0)
104 
105 #define	PTQ_REMOVE(head, elm, field) do {				\
106 	if (((elm)->field.ptqe_next) != NULL)				\
107 		(elm)->field.ptqe_next->field.ptqe_prev = 		\
108 		    (elm)->field.ptqe_prev;				\
109 	else								\
110 		(head)->ptqh_last = (elm)->field.ptqe_prev;		\
111 	*(elm)->field.ptqe_prev = (elm)->field.ptqe_next;		\
112 } while (0)
113 
114 /*
115  * Queue access methods.
116  */
117 
118 #define	PTQ_EMPTY(head)			((head)->ptqh_first == NULL)
119 #define	PTQ_FIRST(head)			((head)->ptqh_first)
120 #define	PTQ_NEXT(elm, field)		((elm)->field.ptqe_next)
121 
122 #define	PTQ_LAST(head, headname)					\
123 	(*(((struct headname *)(void *)((head)->ptqh_last))->ptqh_last))
124 #define	PTQ_PREV(elm, headname, field)					\
125 	(*(((struct headname *)(void *)((elm)->field.ptqe_prev))->ptqh_last))
126 
127 #define	PTQ_FOREACH(var, head, field)					\
128 	for ((var) = ((head)->ptqh_first);				\
129 		(var);							\
130 		(var) = ((var)->field.ptqe_next))
131 
132 #define	PTQ_FOREACH_REVERSE(var, head, headname, field)			\
133 	for ((var) = (*(((struct headname *)(void *)((head)->ptqh_last))->ptqh_last));	\
134 		(var);							\
135 		(var) = (*(((struct headname *)(void *)((var)->field.ptqe_prev))->ptqh_last)))
136 
137 #endif /* _LIB_PTHREAD_QUEUE_H */
138