/*
* Copyright 2016 Jakub Klama <jceel@FreeBSD.org>
* All rights reserved
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted providing that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/queue.h>
#include "lib9p_impl.h"
#include "hashtable.h"
static struct ht_item *ht_iter_advance(struct ht_iter *, struct ht_item *);
void
ht_init(struct ht *h, ssize_t size)
{
ssize_t i;
memset(h, 0, sizeof(struct ht));
h->ht_nentries = size;
h->ht_entries = l9p_calloc((size_t)size, sizeof(struct ht_entry));
pthread_rwlock_init(&h->ht_rwlock, NULL);
for (i = 0; i < size; i++)
TAILQ_INIT(&h->ht_entries[i].hte_items);
}
void
ht_destroy(struct ht *h)
{
struct ht_entry *he;
struct ht_item *item, *tmp;
ssize_t i;
for (i = 0; i < h->ht_nentries; i++) {
he = &h->ht_entries[i];
TAILQ_FOREACH_SAFE(item, &he->hte_items, hti_link, tmp) {
free(item);
}
}
pthread_rwlock_destroy(&h->ht_rwlock);
free(h->ht_entries);
h->ht_entries = NULL;
}
void *
ht_find(struct ht *h, uint32_t hash)
{
void *result;
ht_rdlock(h);
result = ht_find_locked(h, hash);
ht_unlock(h);
return (result);
}
void *
ht_find_locked(struct ht *h, uint32_t hash)
{
struct ht_entry *entry;
struct ht_item *item;
entry = &h->ht_entries[hash % h->ht_nentries];
TAILQ_FOREACH(item, &entry->hte_items, hti_link) {
if (item->hti_hash == hash)
return (item->hti_data);
}
return (NULL);
}
int
ht_add(struct ht *h, uint32_t hash, void *value)
{
struct ht_entry *entry;
struct ht_item *item;
ht_wrlock(h);
entry = &h->ht_entries[hash % h->ht_nentries];
TAILQ_FOREACH(item, &entry->hte_items, hti_link) {
if (item->hti_hash == hash) {
errno = EEXIST;
ht_unlock(h);
return (-1);
}
}
item = l9p_calloc(1, sizeof(struct ht_item));
item->hti_hash = hash;
item->hti_data = value;
TAILQ_INSERT_TAIL(&entry->hte_items, item, hti_link);
ht_unlock(h);
return (0);
}
int
ht_remove(struct ht *h, uint32_t hash)
{
int result;
ht_wrlock(h);
result = ht_remove_locked(h, hash);
ht_unlock(h);
return (result);
}
int
ht_remove_locked(struct ht *h, uint32_t hash)
{
struct ht_entry *entry;
struct ht_item *item, *tmp;
ssize_t slot = hash % h->ht_nentries;
entry = &h->ht_entries[slot];
TAILQ_FOREACH_SAFE(item, &entry->hte_items, hti_link, tmp) {
if (item->hti_hash == hash) {
TAILQ_REMOVE(&entry->hte_items, item, hti_link);
free(item);
return (0);
}
}
errno = ENOENT;
return (-1);
}
/*
* Inner workings for advancing the iterator.
*
* If we have a current item, that tells us how to find the
* next item. If not, we get the first item from the next
* slot (well, the next slot with an item); in any case, we
* record the new slot and return the next item.
*
* For bootstrapping, iter->htit_slot can be -1 to start
* searching at slot 0.
*
* Caller must hold a lock on the table.
*/
static struct ht_item *
ht_iter_advance(struct ht_iter *iter, struct ht_item *cur)
{
struct ht_item *next;
struct ht *h;
ssize_t slot;
h = iter->htit_parent;
if (cur == NULL)
next = NULL;
else
next = TAILQ_NEXT(cur, hti_link);
if (next == NULL) {
slot = iter->htit_slot;
while (++slot < h->ht_nentries) {
next = TAILQ_FIRST(&h->ht_entries[slot].hte_items);
if (next != NULL)
break;
}
iter->htit_slot = slot;
}
return (next);
}
/*
* Remove the current item - there must be one, or this is an
* error. This (necessarily) pre-locates the next item, so callers
* must not use it on an actively-changing table.
*/
int
ht_remove_at_iter(struct ht_iter *iter)
{
struct ht_item *item;
struct ht *h;
ssize_t slot;
assert(iter != NULL);
if ((item = iter->htit_curr) == NULL) {
errno = EINVAL;
return (-1);
}
/* remove the item from the table, saving the NEXT one */
h = iter->htit_parent;
ht_wrlock(h);
slot = iter->htit_slot;
iter->htit_next = ht_iter_advance(iter, item);
TAILQ_REMOVE(&h->ht_entries[slot].hte_items, item, hti_link);
ht_unlock(h);
/* mark us as no longer on an item, then free it */
iter->htit_curr = NULL;
free(item);
return (0);
}
/*
* Initialize iterator. Subsequent ht_next calls will find the
* first item, then the next, and so on. Callers should in general
* not use this on actively-changing tables, though we do our best
* to make it semi-sensible.
*/
void
ht_iter(struct ht *h, struct ht_iter *iter)
{
iter->htit_parent = h;
iter->htit_curr = NULL;
iter->htit_next = NULL;
iter->htit_slot = -1; /* which will increment to 0 */
}
/*
* Return the next item, which is the first item if we have not
* yet been called on this iterator, or the next item if we have.
*/
void *
ht_next(struct ht_iter *iter)
{
struct ht_item *item;
struct ht *h;
if ((item = iter->htit_next) == NULL) {
/* no pre-loaded next; find next from current */
h = iter->htit_parent;
ht_rdlock(h);
item = ht_iter_advance(iter, iter->htit_curr);
ht_unlock(h);
} else
iter->htit_next = NULL;
iter->htit_curr = item;
return (item == NULL ? NULL : item->hti_data);
}
