391 lines
9.0 KiB
C
391 lines
9.0 KiB
C
/* $NetBSD: hash.c,v 1.8 2012/03/12 02:58:55 dholland Exp $ */
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/*
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* Copyright (c) 1992, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This software was developed by the Computer Systems Engineering group
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* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
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* contributed to Berkeley.
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*
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* All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Lawrence Berkeley Laboratories.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)hash.c 8.1 (Berkeley) 6/6/93
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*/
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#if HAVE_NBTOOL_CONFIG_H
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#include "nbtool_config.h"
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#endif
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#include <sys/param.h>
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#include <assert.h>
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#include <stdlib.h>
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#include <string.h>
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#include <util.h>
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#include "defs.h"
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/*
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* Interned strings are kept in a hash table. By making each string
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* unique, the program can compare strings by comparing pointers.
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*/
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struct hashent {
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// XXXLUKEM: a SIMPLEQ might be more appropriate
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TAILQ_ENTRY(hashent) h_next;
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const char *h_name; /* the string */
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u_int h_hash; /* its hash value */
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void *h_value; /* other values (for name=value) */
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};
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struct hashtab {
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size_t ht_size; /* size (power of 2) */
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u_int ht_mask; /* == ht_size - 1 */
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u_int ht_used; /* number of entries used */
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u_int ht_lim; /* when to expand */
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TAILQ_HEAD(hashenthead, hashent) *ht_tab;
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};
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static struct hashtab strings;
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/*
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* HASHFRACTION controls ht_lim, which in turn controls the average chain
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* length. We allow a few entries, on average, as comparing them is usually
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* cheap (the h_hash values prevent a strcmp).
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*/
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#define HASHFRACTION(sz) ((sz) * 3 / 2)
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static void ht_expand(struct hashtab *);
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static void ht_init(struct hashtab *, size_t);
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static inline u_int hash(const char *);
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static inline struct hashent *newhashent(const char *, u_int);
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/*
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* Initialize a new hash table. The size must be a power of 2.
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*/
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static void
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ht_init(struct hashtab *ht, size_t sz)
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{
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u_int n;
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ht->ht_tab = emalloc(sz * sizeof (ht->ht_tab[0]));
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ht->ht_size = sz;
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ht->ht_mask = sz - 1;
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for (n = 0; n < sz; n++)
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TAILQ_INIT(&ht->ht_tab[n]);
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ht->ht_used = 0;
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ht->ht_lim = HASHFRACTION(sz);
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}
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/*
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* Expand an existing hash table.
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*/
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static void
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ht_expand(struct hashtab *ht)
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{
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struct hashenthead *h, *oldh;
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struct hashent *p;
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u_int n, i;
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n = ht->ht_size * 2;
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h = emalloc(n * sizeof *h);
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for (i = 0; i < n; i++)
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TAILQ_INIT(&h[i]);
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oldh = ht->ht_tab;
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n--;
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for (i = 0; i < ht->ht_size; i++) {
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while ((p = TAILQ_FIRST(&oldh[i])) != NULL) {
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TAILQ_REMOVE(&oldh[i], p, h_next);
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// XXXLUKEM: really should be TAILQ_INSERT_TAIL
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TAILQ_INSERT_HEAD(&h[p->h_hash & n], p, h_next);
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}
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}
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free(ht->ht_tab);
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ht->ht_tab = h;
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ht->ht_mask = n;
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ht->ht_size = ++n;
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ht->ht_lim = HASHFRACTION(n);
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}
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/*
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* Make a new hash entry, setting its h_next to NULL.
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* If the free list is not empty, use the first entry from there,
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* otherwise allocate a new entry.
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*/
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static inline struct hashent *
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newhashent(const char *name, u_int h)
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{
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struct hashent *hp;
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hp = ecalloc(1, sizeof(*hp));
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hp->h_name = name;
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hp->h_hash = h;
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return (hp);
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}
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/*
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* Hash a string.
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*/
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static inline u_int
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hash(const char *str)
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{
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u_int h;
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for (h = 0; *str;)
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h = (h << 5) + h + *str++;
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return (h);
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}
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void
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initintern(void)
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{
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ht_init(&strings, 128);
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}
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/*
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* Generate a single unique copy of the given string. We expect this
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* function to be used frequently, so it should be fast.
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*/
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const char *
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intern(const char *s)
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{
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struct hashtab *ht;
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struct hashent *hp;
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struct hashenthead *hpp;
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u_int h;
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char *p;
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ht = &strings;
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h = hash(s);
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hpp = &ht->ht_tab[h & ht->ht_mask];
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TAILQ_FOREACH(hp, hpp, h_next) {
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if (hp->h_hash == h && strcmp(hp->h_name, s) == 0)
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return (hp->h_name);
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}
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p = estrdup(s);
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hp = newhashent(p, h);
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TAILQ_INSERT_TAIL(hpp, hp, h_next);
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if (++ht->ht_used > ht->ht_lim)
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ht_expand(ht);
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return (p);
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}
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struct hashtab *
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ht_new(void)
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{
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struct hashtab *ht;
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ht = ecalloc(1, sizeof *ht);
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ht_init(ht, 8);
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return (ht);
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}
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void
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ht_free(struct hashtab *ht)
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{
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size_t i;
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struct hashent *hp;
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struct hashenthead *hpp;
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for (i = 0; i < ht->ht_size; i++) {
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hpp = &ht->ht_tab[i];
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while ((hp = TAILQ_FIRST(hpp)) != NULL) {
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TAILQ_REMOVE(hpp, hp, h_next);
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free(hp);
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ht->ht_used--;
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}
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}
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assert(ht->ht_used == 0);
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free(ht->ht_tab);
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free(ht);
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}
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/*
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* Insert and/or replace.
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*/
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int
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ht_insrep(struct hashtab *ht, const char *nam, void *val, int replace)
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{
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struct hashent *hp;
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struct hashenthead *hpp;
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u_int h;
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h = hash(nam);
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hpp = &ht->ht_tab[h & ht->ht_mask];
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TAILQ_FOREACH(hp, hpp, h_next) {
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if (hp->h_name == nam) {
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if (replace)
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hp->h_value = val;
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return (1);
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}
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}
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hp = newhashent(nam, h);
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TAILQ_INSERT_TAIL(hpp, hp, h_next);
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hp->h_value = val;
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if (++ht->ht_used > ht->ht_lim)
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ht_expand(ht);
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return (0);
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}
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/*
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* Remove.
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*/
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int
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ht_remove(struct hashtab *ht, const char *name)
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{
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struct hashent *hp;
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struct hashenthead *hpp;
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u_int h;
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h = hash(name);
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hpp = &ht->ht_tab[h & ht->ht_mask];
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TAILQ_FOREACH(hp, hpp, h_next) {
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if (hp->h_name != name)
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continue;
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TAILQ_REMOVE(hpp, hp, h_next);
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free(hp);
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ht->ht_used--;
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return (0);
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}
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return (1);
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}
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void *
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ht_lookup(struct hashtab *ht, const char *nam)
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{
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struct hashent *hp;
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struct hashenthead *hpp;
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u_int h;
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h = hash(nam);
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hpp = &ht->ht_tab[h & ht->ht_mask];
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TAILQ_FOREACH(hp, hpp, h_next)
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if (hp->h_name == nam)
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return (hp->h_value);
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return (NULL);
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}
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/*
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* first parameter to callback is the entry name from the hash table
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* second parameter is the value from the hash table
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* third argument is passed through from the "arg" parameter to ht_enumerate()
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*/
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int
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ht_enumerate(struct hashtab *ht, ht_callback cbfunc, void *arg)
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{
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struct hashent *hp;
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struct hashenthead *hpp;
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size_t i;
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int rval = 0;
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for (i = 0; i < ht->ht_size; i++) {
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hpp = &ht->ht_tab[i];
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TAILQ_FOREACH(hp, hpp, h_next)
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rval += (*cbfunc)(hp->h_name, hp->h_value, arg);
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}
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return rval;
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}
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/************************************************************/
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/*
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* Type-safe wrappers.
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*/
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#define DEFHASH(HT, VT) \
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struct HT { \
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struct hashtab imp; \
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}; \
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\
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struct HT * \
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HT##_create(void) \
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{ \
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struct HT *tbl; \
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\
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tbl = ecalloc(1, sizeof(*tbl)); \
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ht_init(&tbl->imp, 8); \
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return tbl; \
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} \
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\
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int \
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HT##_insert(struct HT *tbl, const char *name, struct VT *val) \
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{ \
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return ht_insert(&tbl->imp, name, val); \
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} \
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\
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int \
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HT##_replace(struct HT *tbl, const char *name, struct VT *val) \
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{ \
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return ht_replace(&tbl->imp, name, val); \
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} \
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\
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int \
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HT##_remove(struct HT *tbl, const char *name) \
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{ \
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return ht_remove(&tbl->imp, name); \
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} \
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\
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struct VT * \
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HT##_lookup(struct HT *tbl, const char *name) \
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{ \
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return ht_lookup(&tbl->imp, name); \
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} \
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\
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struct HT##_enumcontext { \
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int (*func)(const char *, struct VT *, void *); \
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void *userctx; \
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}; \
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\
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static int \
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HT##_enumerate_thunk(const char *name, void *value, void *voidctx) \
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{ \
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struct HT##_enumcontext *ctx = voidctx; \
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\
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return ctx->func(name, value, ctx->userctx); \
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} \
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\
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int \
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HT##_enumerate(struct HT *tbl, \
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int (*func)(const char *, struct VT *, void *), \
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void *userctx) \
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{ \
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struct HT##_enumcontext ctx; \
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\
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ctx.func = func; \
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ctx.userctx = userctx; \
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return ht_enumerate(&tbl->imp, HT##_enumerate_thunk, &ctx); \
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}
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DEFHASH(nvhash, nvlist);
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DEFHASH(dlhash, defoptlist);
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