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/*
Copyright (C) 2017 Paweł Redman
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 3
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "shared.h"
#define HASH_MAX 4095
static size_t cache_hash(uint32_t ipv4)
{
// FIXME: Use an academically acclaimed hashing algorithm.
return (((ipv4 >> 16) ^ ipv4) * 3137) & HASH_MAX;
}
static cache_entry_t *cache_ht[HASH_MAX];
static pthread_mutex_t cache_mutex = PTHREAD_MUTEX_INITIALIZER;
// Returns an entry with its mutex locked.
cache_entry_t *cache_find(uint32_t ipv4)
{
cache_entry_t *entry;
size_t hash;
hash = cache_hash(ipv4);
pthread_mutex_lock(&cache_mutex);
eli_for (entry, cache_ht[hash], ht_list)
if (entry->ipv4 == ipv4)
break;
if (!entry) {
entry = calloc(1, sizeof(cache_entry_t));
entry->ipv4 = ipv4;
pthread_mutex_init(&entry->mutex, NULL);
eli_append(cache_ht + hash, entry, ht_list);
}
pthread_mutex_lock(&entry->mutex);
pthread_mutex_unlock(&cache_mutex);
return entry;
}
void cache_destroy(void)
{
size_t i;
cache_entry_t *entry, *next;
for (i = 0; i < HASH_MAX; i++) {
for (entry = cache_ht[i]; entry; entry = next) {
next = entry->ht_list.next;
free(entry->revdns);
free(entry->whois);
free(entry);
}
cache_ht[i] = NULL;
}
}
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