268 lines
6.1 KiB
C
268 lines
6.1 KiB
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 <pthread.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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static struct ht_item *ht_iter_advance(struct ht_iter *, struct ht_item *);
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void
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ht_init(struct ht *h, ssize_t size)
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{
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ssize_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_t)size, sizeof(struct ht_entry));
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pthread_rwlock_init(&h->ht_rwlock, NULL);
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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 *item, *tmp;
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ssize_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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TAILQ_FOREACH_SAFE(item, &he->hte_items, hti_link, tmp) {
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free(item);
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}
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}
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pthread_rwlock_destroy(&h->ht_rwlock);
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free(h->ht_entries);
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h->ht_entries = NULL;
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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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void *result;
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ht_rdlock(h);
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result = ht_find_locked(h, hash);
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ht_unlock(h);
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return (result);
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}
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void *
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ht_find_locked(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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ht_wrlock(h);
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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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ht_unlock(h);
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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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ht_unlock(h);
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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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int result;
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ht_wrlock(h);
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result = ht_remove_locked(h, hash);
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ht_unlock(h);
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return (result);
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}
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int
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ht_remove_locked(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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ssize_t 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);
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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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/*
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* Inner workings for advancing the iterator.
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*
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* If we have a current item, that tells us how to find the
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* next item. If not, we get the first item from the next
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* slot (well, the next slot with an item); in any case, we
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* record the new slot and return the next item.
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*
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* For bootstrapping, iter->htit_slot can be -1 to start
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* searching at slot 0.
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*
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* Caller must hold a lock on the table.
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*/
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static struct ht_item *
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ht_iter_advance(struct ht_iter *iter, struct ht_item *cur)
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{
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struct ht_item *next;
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struct ht *h;
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ssize_t slot;
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h = iter->htit_parent;
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if (cur == NULL)
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next = NULL;
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else
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next = TAILQ_NEXT(cur, hti_link);
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if (next == NULL) {
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slot = iter->htit_slot;
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while (++slot < h->ht_nentries) {
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next = TAILQ_FIRST(&h->ht_entries[slot].hte_items);
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if (next != NULL)
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break;
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}
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iter->htit_slot = slot;
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}
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return (next);
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}
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/*
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* Remove the current item - there must be one, or this is an
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* error. This (necessarily) pre-locates the next item, so callers
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* must not use it on an actively-changing table.
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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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struct ht_item *item;
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struct ht *h;
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ssize_t slot;
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assert(iter != NULL);
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if ((item = iter->htit_curr) == NULL) {
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errno = EINVAL;
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return (-1);
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}
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/* remove the item from the table, saving the NEXT one */
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h = iter->htit_parent;
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ht_wrlock(h);
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slot = iter->htit_slot;
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iter->htit_next = ht_iter_advance(iter, item);
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TAILQ_REMOVE(&h->ht_entries[slot].hte_items, item, hti_link);
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ht_unlock(h);
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/* mark us as no longer on an item, then free it */
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iter->htit_curr = NULL;
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free(item);
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return (0);
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}
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/*
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* Initialize iterator. Subsequent ht_next calls will find the
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* first item, then the next, and so on. Callers should in general
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* not use this on actively-changing tables, though we do our best
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* to make it semi-sensible.
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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_curr = NULL;
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iter->htit_next = NULL;
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iter->htit_slot = -1; /* which will increment to 0 */
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}
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/*
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* Return the next item, which is the first item if we have not
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* yet been called on this iterator, or the next item if we have.
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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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struct ht *h;
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if ((item = iter->htit_next) == NULL) {
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/* no pre-loaded next; find next from current */
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h = iter->htit_parent;
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ht_rdlock(h);
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item = ht_iter_advance(iter, iter->htit_curr);
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ht_unlock(h);
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} else
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iter->htit_next = NULL;
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iter->htit_curr = item;
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return (item == NULL ? NULL : item->hti_data);
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}
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