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/* $OpenBSD: ohash.c,v 1.1 2014/06/02 18:52:03 deraadt Exp $ */
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/* Copyright (c) 1999, 2004 Marc Espie <espie@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <limits.h>
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#include "ohash.h"
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struct _ohash_record {
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uint32_t hv;
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const char *p;
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};
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#define DELETED ((const char *)h)
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#define NONE (h->size)
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/* Don't bother changing the hash table if the change is small enough. */
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#define MINSIZE (1UL << 4)
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#define MINDELETED 4
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static void ohash_resize(struct ohash *);
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/* This handles the common case of variable length keys, where the
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* key is stored at the end of the record.
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*/
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void *
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ohash_create_entry(struct ohash_info *i, const char *start, const char **end)
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{
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char *p;
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if (!*end)
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*end = start + strlen(start);
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p = (i->alloc)(i->key_offset + (*end - start) + 1, i->data);
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if (p) {
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memcpy(p+i->key_offset, start, *end-start);
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p[i->key_offset + (*end - start)] = '\0';
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}
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return (void *)p;
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}
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/* hash_delete only frees the hash structure. Use hash_first/hash_next
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* to free entries as well. */
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void
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ohash_delete(struct ohash *h)
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{
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(h->info.free)(h->t, h->info.data);
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#ifndef NDEBUG
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h->t = NULL;
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#endif
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}
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static void
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ohash_resize(struct ohash *h)
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{
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struct _ohash_record *n;
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size_t ns;
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unsigned int j;
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unsigned int i, incr;
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if (4 * h->deleted < h->total) {
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if (h->size >= (UINT_MAX >> 1U))
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ns = UINT_MAX;
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else
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ns = h->size << 1U;
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} else if (3 * h->deleted > 2 * h->total)
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ns = h->size >> 1U;
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else
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ns = h->size;
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if (ns < MINSIZE)
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ns = MINSIZE;
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#ifdef STATS_HASH
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STAT_HASH_EXPAND++;
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STAT_HASH_SIZE += ns - h->size;
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#endif
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n = (h->info.calloc)(ns, sizeof(struct _ohash_record), h->info.data);
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if (!n)
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return;
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for (j = 0; j < h->size; j++) {
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if (h->t[j].p != NULL && h->t[j].p != DELETED) {
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i = h->t[j].hv % ns;
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incr = ((h->t[j].hv % (ns - 2)) & ~1) + 1;
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while (n[i].p != NULL) {
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i += incr;
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if (i >= ns)
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i -= ns;
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}
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n[i].hv = h->t[j].hv;
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n[i].p = h->t[j].p;
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}
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}
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(h->info.free)(h->t, h->info.data);
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h->t = n;
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h->size = ns;
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h->total -= h->deleted;
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h->deleted = 0;
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}
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void *
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ohash_remove(struct ohash *h, unsigned int i)
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{
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void *result = (void *)h->t[i].p;
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if (result == NULL || result == DELETED)
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return NULL;
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#ifdef STATS_HASH
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STAT_HASH_ENTRIES--;
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#endif
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h->t[i].p = DELETED;
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h->deleted++;
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if (h->deleted >= MINDELETED && 4 * h->deleted > h->total)
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ohash_resize(h);
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return result;
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}
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void *
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ohash_find(struct ohash *h, unsigned int i)
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{
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if (h->t[i].p == DELETED)
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return NULL;
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else
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return (void *)h->t[i].p;
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}
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void *
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ohash_insert(struct ohash *h, unsigned int i, void *p)
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{
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#ifdef STATS_HASH
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STAT_HASH_ENTRIES++;
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#endif
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if (h->t[i].p == DELETED) {
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h->deleted--;
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h->t[i].p = p;
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} else {
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h->t[i].p = p;
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/* Arbitrary resize boundary. Tweak if not efficient enough. */
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if (++h->total * 4 > h->size * 3)
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ohash_resize(h);
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}
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return p;
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}
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unsigned int
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ohash_entries(struct ohash *h)
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{
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return h->total - h->deleted;
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}
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void *
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ohash_first(struct ohash *h, unsigned int *pos)
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{
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*pos = 0;
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return ohash_next(h, pos);
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}
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void *
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ohash_next(struct ohash *h, unsigned int *pos)
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{
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for (; *pos < h->size; (*pos)++)
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if (h->t[*pos].p != DELETED && h->t[*pos].p != NULL)
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return (void *)h->t[(*pos)++].p;
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return NULL;
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}
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void
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ohash_init(struct ohash *h, unsigned int size, struct ohash_info *info)
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{
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h->size = 1UL << size;
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if (h->size < MINSIZE)
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h->size = MINSIZE;
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#ifdef STATS_HASH
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STAT_HASH_CREATION++;
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STAT_HASH_SIZE += h->size;
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#endif
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/* Copy info so that caller may free it. */
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h->info.key_offset = info->key_offset;
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h->info.calloc = info->calloc;
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h->info.free = info->free;
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h->info.alloc = info->alloc;
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h->info.data = info->data;
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h->t = (h->info.calloc)(h->size, sizeof(struct _ohash_record),
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h->info.data);
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h->total = h->deleted = 0;
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}
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uint32_t
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ohash_interval(const char *s, const char **e)
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{
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uint32_t k;
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if (!*e)
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*e = s + strlen(s);
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if (s == *e)
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k = 0;
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else
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k = *s++;
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while (s != *e)
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k = ((k << 2) | (k >> 30)) ^ *s++;
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return k;
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}
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unsigned int
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ohash_lookup_interval(struct ohash *h, const char *start, const char *end,
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uint32_t hv)
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{
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unsigned int i, incr;
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unsigned int empty;
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#ifdef STATS_HASH
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STAT_HASH_LOOKUP++;
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#endif
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empty = NONE;
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i = hv % h->size;
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incr = ((hv % (h->size-2)) & ~1) + 1;
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while (h->t[i].p != NULL) {
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#ifdef STATS_HASH
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STAT_HASH_LENGTH++;
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#endif
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if (h->t[i].p == DELETED) {
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if (empty == NONE)
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empty = i;
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} else if (h->t[i].hv == hv &&
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strncmp(h->t[i].p+h->info.key_offset, start,
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end - start) == 0 &&
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(h->t[i].p+h->info.key_offset)[end-start] == '\0') {
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if (empty != NONE) {
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h->t[empty].hv = hv;
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h->t[empty].p = h->t[i].p;
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h->t[i].p = DELETED;
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return empty;
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} else {
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#ifdef STATS_HASH
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STAT_HASH_POSITIVE++;
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#endif
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return i;
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}
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}
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i += incr;
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if (i >= h->size)
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i -= h->size;
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}
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/* Found an empty position. */
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if (empty != NONE)
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i = empty;
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h->t[i].hv = hv;
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return i;
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}
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unsigned int
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ohash_lookup_memory(struct ohash *h, const char *k, size_t size, uint32_t hv)
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{
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unsigned int i, incr;
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unsigned int empty;
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#ifdef STATS_HASH
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STAT_HASH_LOOKUP++;
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#endif
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empty = NONE;
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i = hv % h->size;
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incr = ((hv % (h->size-2)) & ~1) + 1;
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while (h->t[i].p != NULL) {
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#ifdef STATS_HASH
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STAT_HASH_LENGTH++;
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#endif
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if (h->t[i].p == DELETED) {
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if (empty == NONE)
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empty = i;
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} else if (h->t[i].hv == hv &&
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memcmp(h->t[i].p+h->info.key_offset, k, size) == 0) {
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if (empty != NONE) {
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h->t[empty].hv = hv;
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h->t[empty].p = h->t[i].p;
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h->t[i].p = DELETED;
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return empty;
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} else {
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#ifdef STATS_HASH
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STAT_HASH_POSITIVE++;
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#endif
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} return i;
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}
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i += incr;
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if (i >= h->size)
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i -= h->size;
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}
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/* Found an empty position. */
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if (empty != NONE)
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i = empty;
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h->t[i].hv = hv;
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return i;
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}
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unsigned int
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ohash_qlookup(struct ohash *h, const char *s)
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{
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const char *e = NULL;
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return ohash_qlookupi(h, s, &e);
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}
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unsigned int
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ohash_qlookupi(struct ohash *h, const char *s, const char **e)
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{
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uint32_t hv;
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hv = ohash_interval(s, e);
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return ohash_lookup_interval(h, s, *e, hv);
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}
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