Add simple hashtable implementation.
This is to replace using inefficient lists to store tags and fids.
This commit is contained in:
Jakub Klama
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830759c75e
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c9624690a9
2 changed files with 235 additions and 0 deletions
172
hashtable.c
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172
hashtable.c
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/*
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* Copyright 2016 Jakub Klama <jceel@FreeBSD.org>
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* All rights reserved
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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 providing 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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* 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,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <assert.h>
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#include <sys/types.h>
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#include <sys/queue.h>
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#include "lib9p_impl.h"
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#include "hashtable.h"
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void
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ht_init(struct ht *h, size_t size)
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{
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size_t i;
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memset(h, 0, sizeof(struct ht));
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h->ht_nentries = size;
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h->ht_entries = l9p_calloc(size, sizeof(struct ht_entry));
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for (i = 0; i < size; i++)
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TAILQ_INIT(&h->ht_entries[i].hte_items);
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}
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void
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ht_destroy(struct ht *h)
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{
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struct ht_entry *he;
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struct ht_item *hi;
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size_t i;
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for (i = 0; i < h->ht_nentries; i++) {
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he = &h->ht_entries[i];
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hi = TAILQ_FIRST(&he->hte_items);
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while ((hi = TAILQ_NEXT(hi, hti_link)) != NULL)
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TAILQ_REMOVE(&he->hte_items, hi, hti_link);
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}
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free(h->ht_entries);
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free(h);
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}
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void *
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ht_find(struct ht *h, uint32_t hash)
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{
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struct ht_entry *entry;
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struct ht_item *item;
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entry = &h->ht_entries[hash % h->ht_nentries];
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TAILQ_FOREACH(item, &entry->hte_items, hti_link) {
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if (item->hti_hash == hash)
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return (item->hti_data);
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}
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return (NULL);
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}
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int
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ht_add(struct ht *h, uint32_t hash, void *value)
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{
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struct ht_entry *entry;
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struct ht_item *item;
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entry = &h->ht_entries[hash % h->ht_nentries];
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TAILQ_FOREACH(item, &entry->hte_items, hti_link) {
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if (item->hti_hash == hash) {
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errno = EEXIST;
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return (-1);
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}
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}
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item = l9p_calloc(1, sizeof(struct ht_item));
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item->hti_hash = hash;
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item->hti_data = value;
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TAILQ_INSERT_TAIL(&entry->hte_items, item, hti_link);
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return (0);
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}
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int
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ht_remove(struct ht *h, uint32_t hash)
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{
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struct ht_entry *entry;
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struct ht_item *item, *tmp;
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int slot = hash % h->ht_nentries;
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entry = &h->ht_entries[slot];
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TAILQ_FOREACH_SAFE(item, &entry->hte_items, hti_link, tmp) {
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if (item->hti_hash == hash) {
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TAILQ_REMOVE(&entry->hte_items, item, hti_link);
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free(item->hti_data);
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free(item);
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return (0);
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}
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}
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errno = ENOENT;
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return (-1);
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}
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int
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ht_remove_at_iter(struct ht_iter *iter)
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{
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assert(iter != NULL);
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if (iter->htit_cursor == NULL) {
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errno = EINVAL;
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return (-1);
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}
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TAILQ_REMOVE(&iter->htit_parent->ht_entries[iter->htit_slot].hte_items,
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iter->htit_cursor, hti_link);
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return (0);
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}
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void
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ht_iter(struct ht *h, struct ht_iter *iter)
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{
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iter->htit_parent = h;
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iter->htit_slot = 0;
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iter->htit_cursor = TAILQ_FIRST(&h->ht_entries[0].hte_items);
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}
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void *
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ht_next(struct ht_iter *iter)
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{
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struct ht_item *item;
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item = iter->htit_cursor;
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retry:
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if ((iter->htit_cursor = TAILQ_NEXT(iter->htit_cursor, hti_link)) == NULL)
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{
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if (iter->htit_slot == iter->htit_parent->ht_nentries)
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return (NULL);
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iter->htit_slot++;
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goto retry;
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}
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return (item);
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}
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63
hashtable.h
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63
hashtable.h
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@ -0,0 +1,63 @@
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/*
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* Copyright 2016 Jakub Klama <jceel@FreeBSD.org>
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* All rights reserved
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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 providing 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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* 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,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#ifndef LIB9P_HASHTABLE_H
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#define LIB9P_HASHTABLE_H
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#include <sys/queue.h>
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struct ht {
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struct ht_entry * ht_entries;
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size_t ht_nentries;
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};
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struct ht_entry {
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TAILQ_HEAD(, ht_item) hte_items;
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};
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struct ht_item {
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uint32_t hti_hash;
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void * hti_data;
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TAILQ_ENTRY(ht_item) hti_link;
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};
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struct ht_iter {
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struct ht * htit_parent;
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struct ht_item * htit_cursor;
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size_t htit_slot;
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};
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void ht_init(struct ht *h, size_t size);
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void ht_destroy(struct ht *h);
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void *ht_find(struct ht *h, uint32_t hash);
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int ht_add(struct ht *h, uint32_t hash, void *value);
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int ht_remove(struct ht *h, uint32_t hash);
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int ht_remove_at_iter(struct ht_iter *iter);
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void ht_iter(struct ht *h, struct ht_iter *iter);
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void *ht_next(struct ht_iter *iter);
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#endif /* LIB9P_HASHTABLE_H */
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