kobj.h revision 59602 
1/*-
2 * Copyright (c) 2000 Doug Rabson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 *	$FreeBSD: head/sys/sys/kobj.h 59602 2000-04-24 16:59:46Z dfr $
27 */
28
29#ifndef _SYS_KOBJ_H_
30#define _SYS_KOBJ_H_
31
32/*
33 * Forward declarations
34 */
35typedef struct kobj		*kobj_t;
36typedef struct kobj_class	*kobj_class_t;
37typedef struct kobj_method	kobj_method_t;
38typedef int			(*kobjop_t)(void);
39typedef struct kobj_ops		*kobj_ops_t;
40typedef struct kobjop_desc	*kobjop_desc_t;
41struct malloc_type;
42
43struct kobj_method {
44	kobjop_desc_t	desc;
45	kobjop_t	func;
46};
47
48/*
49 * A class is simply a method table and a sizeof value. When the first
50 * instance of the class is created, the method table will be compiled
51 * into a form more suited to efficient method dispatch. This compiled
52 * method table is always the first field of the object.
53 */
54#define KOBJ_CLASS_FIELDS						\
55	const char	*name;		/* class name */		\
56	kobj_method_t	*methods;	/* method table */		\
57	size_t		size;		/* object size */		\
58	u_int		instances;	/* instance count */		\
59	kobj_ops_t	ops		/* compiled method table */
60
61struct kobj_class {
62	KOBJ_CLASS_FIELDS;
63};
64
65/*
66 * Implementation of kobj.
67 */
68#define KOBJ_FIELDS				\
69	kobj_ops_t	ops;
70
71struct kobj {
72	KOBJ_FIELDS;
73};
74
75/*
76 * The ops table is used as a cache of results from kobj_lookup_method().
77 */
78
79#define KOBJ_CACHE_SIZE	256
80
81struct kobj_ops {
82	kobj_method_t	cache[KOBJ_CACHE_SIZE];
83	kobj_class_t	cls;
84};
85
86struct kobjop_desc {
87	unsigned int	id;	/* unique ID */
88	kobjop_t	deflt;	/* default implementation */
89};
90
91/*
92 * Shorthand for constructing method tables.
93 */
94#define KOBJMETHOD(NAME, FUNC) { &NAME##_desc, (kobjop_t) FUNC }
95
96#define DEFINE_CLASS(name, methods, size)	\
97						\
98struct kobj_class name ## _class = {		\
99	#name, methods, size			\
100}
101
102/*
103 * Compile the method table in a class.
104 */
105void		kobj_class_compile(kobj_class_t cls);
106
107/*
108 * Free the compiled method table in a class.
109 */
110void		kobj_class_free(kobj_class_t cls);
111
112/*
113 * Allocate memory for and initalise a new object.
114 */
115kobj_t		kobj_create(kobj_class_t cls,
116			    struct malloc_type *mtype,
117			    int mflags);
118
119/*
120 * Initialise a pre-allocated object.
121 */
122void		kobj_init(kobj_t obj, kobj_class_t cls);
123
124/*
125 * Delete an object. If mtype is non-zero, free the memory.
126 */
127void		kobj_delete(kobj_t obj, struct malloc_type *mtype);
128
129/*
130 * Maintain stats on hits/misses in lookup caches.
131 */
132#ifdef KOBJ_STATS
133extern int kobj_lookup_hits;
134extern int kobj_lookup_misses;
135#define KOBJOPHIT	do { kobj_lookup_hits++; } while (0)
136#define KOBJOPMISS	do { kobj_lookup_misses++; } while (0)
137#else
138#define KOBJOPHIT	do { } while (0)
139#define KOBJOPMISS	do { } while (0)
140#endif
141
142/*
143 * Lookup the method in the cache and if it isn't there look it up the
144 * slow way.
145 */
146#define KOBJOPLOOKUP(OPS,OP) do {					\
147	kobjop_desc_t _desc = &OP##_##desc;				\
148	kobj_method_t *_ce =						\
149	    &OPS->cache[_desc->id & (KOBJ_CACHE_SIZE-1)];		\
150	if (_ce->desc != _desc) {					\
151		KOBJOPMISS;						\
152		kobj_lookup_method(OPS->cls->methods, _ce, _desc);	\
153	} else {							\
154		KOBJOPHIT;						\
155	}								\
156	_m = _ce->func;							\
157} while(0)
158
159void kobj_lookup_method(kobj_method_t *methods,
160			kobj_method_t *ce,
161			kobjop_desc_t desc);
162
163#endif /* !_SYS_KOBJ_H_ */
164