1/* $OpenBSD: ohash_do.c,v 1.4 2004/06/22 20:00:16 espie Exp $ */
2/* ex:ts=8 sw=4:
3 */
4
5/* Copyright (c) 1999, 2004 Marc Espie <espie@openbsd.org>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19#include <sys/cdefs.h>
20__FBSDID("$FreeBSD$");
21
22#include "ohash_int.h"
23
24static void ohash_resize(struct ohash *);
25
26static void
27ohash_resize(struct ohash *h)
28{
29	struct _ohash_record *n;
30	unsigned int 	ns, j;
31	unsigned int	i, incr;
32
33	if (4 * h->deleted < h->total)
34		ns = h->size << 1;
35	else if (3 * h->deleted > 2 * h->total)
36		ns = h->size >> 1;
37	else
38		ns = h->size;
39	if (ns < MINSIZE)
40		ns = MINSIZE;
41#ifdef STATS_HASH
42	STAT_HASH_EXPAND++;
43	STAT_HASH_SIZE += ns - h->size;
44#endif
45	n = (h->info.halloc)(sizeof(struct _ohash_record) * ns, h->info.data);
46	if (!n)
47		return;
48
49	for (j = 0; j < h->size; j++) {
50		if (h->t[j].p != NULL && h->t[j].p != DELETED) {
51			i = h->t[j].hv % ns;
52			incr = ((h->t[j].hv % (ns - 2)) & ~1) + 1;
53			while (n[i].p != NULL) {
54				i += incr;
55				if (i >= ns)
56					i -= ns;
57		    	}
58			n[i].hv = h->t[j].hv;
59			n[i].p = h->t[j].p;
60		}
61	}
62	(h->info.hfree)(h->t, sizeof(struct _ohash_record) * h->size,
63		h->info.data);
64	h->t = n;
65	h->size = ns;
66	h->total -= h->deleted;
67	h->deleted = 0;
68}
69
70void *
71ohash_remove(struct ohash *h, unsigned int i)
72{
73	void 		*result = __DECONST(void *, h->t[i].p);
74
75	if (result == NULL || result == DELETED)
76		return NULL;
77
78#ifdef STATS_HASH
79	STAT_HASH_ENTRIES--;
80#endif
81	h->t[i].p = DELETED;
82	h->deleted++;
83	if (h->deleted >= MINDELETED && 4 * h->deleted > h->total)
84		ohash_resize(h);
85	return result;
86}
87
88void *
89ohash_find(struct ohash *h, unsigned int i)
90{
91	if (h->t[i].p == DELETED)
92		return NULL;
93	else
94		return __DECONST(void *, h->t[i].p);
95}
96
97void *
98ohash_insert(struct ohash *h, unsigned int i, void *p)
99{
100#ifdef STATS_HASH
101	STAT_HASH_ENTRIES++;
102#endif
103	if (h->t[i].p == DELETED) {
104		h->deleted--;
105		h->t[i].p = p;
106	} else {
107		h->t[i].p = p;
108	/* Arbitrary resize boundary.  Tweak if not efficient enough.  */
109		if (++h->total * 4 > h->size * 3)
110			ohash_resize(h);
111	}
112    	return p;
113}
114