1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 1999 Michael Smith <msmith@freebsd.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * $FreeBSD$
29 */
30
31#ifndef _SYS__EVENTHANDLER_H_
32#define _SYS__EVENTHANDLER_H_
33
34#include <sys/queue.h>
35
36struct eventhandler_entry {
37	TAILQ_ENTRY(eventhandler_entry)	ee_link;
38	int				ee_priority;
39#define	EHE_DEAD_PRIORITY	(-1)
40	void				*ee_arg;
41};
42
43typedef struct eventhandler_entry	*eventhandler_tag;
44
45/*
46 * You can optionally use the EVENTHANDLER_LIST and EVENTHANDLER_DIRECT macros
47 * to pre-define a symbol for the eventhandler list. This symbol can be used by
48 * EVENTHANDLER_DIRECT_INVOKE, which has the advantage of not needing to do a
49 * locked search of the global list of eventhandler lists. At least
50 * EVENTHANDLER_LIST_DEFINE must be be used for EVENTHANDLER_DIRECT_INVOKE to
51 * work. EVENTHANDLER_LIST_DECLARE is only needed if the call to
52 * EVENTHANDLER_DIRECT_INVOKE is in a different compilation unit from
53 * EVENTHANDLER_LIST_DEFINE. If the events are even relatively high frequency
54 * it is suggested that you directly define a list for them.
55 */
56struct eventhandler_list;
57#define	EVENTHANDLER_LIST_DECLARE(name)					\
58extern struct eventhandler_list *_eventhandler_list_ ## name		\
59
60/*
61 * Event handlers need to be declared, but do not need to be defined. The
62 * declaration must be in scope wherever the handler is to be invoked.
63 */
64#define EVENTHANDLER_DECLARE(name, type)				\
65struct eventhandler_entry_ ## name 					\
66{									\
67	struct eventhandler_entry	ee;				\
68	type				eh_func;			\
69};									\
70struct __hack
71
72#endif
73