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/*
This file is part of GNUnet.
(C) 2012 Christian Grothoff (and other contributing authors)
GNUnet 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 2, or (at your
option) any later version.
GNUnet 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 GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
/**
* @file testbed/gnunet-service-testbed_hc.h
* @brief testbed cache implementation
* @author Sree Harsha Totakura
*/
#include "gnunet-service-testbed.h"
/**
* Cache entry
*/
struct CacheEntry
{
/**
* DLL next ptr for least recently used cache entries
*/
struct CacheEntry *next;
/**
* DLL prev ptr for least recently used cache entries
*/
struct CacheEntry *prev;
/**
* The key for this entry
*/
struct GNUNET_HashCode key;
/**
* The HELLO message
*/
struct GNUNET_MessageHeader *hello;
};
/**
* Hashmap to maintain cache
*/
static struct GNUNET_CONTAINER_MultiHashMap *cache;
/**
* DLL head for least recently used cache entries; least recently used
* cache items are at the head
*/
static struct CacheEntry *lru_hcache_head;
/**
* DLL tail for least recently used cache entries; recently used cache
* items are at the tail
*/
static struct CacheEntry *lru_hcache_tail;
/**
* The size of cache
*/
static unsigned int cache_size;
/**
* Looks up in the cache and returns the HELLO of the given peer
*
* @param id the peer identity of the peer whose HELLO has to be looked up
* @return the HELLO message; NULL if not found
*/
const struct GNUNET_MessageHeader *
GST_cache_lookup (const struct GNUNET_PeerIdentity *id)
{
struct CacheEntry *entry;
if (NULL == cache)
return NULL;
entry = GNUNET_CONTAINER_multihashmap_get (cache, &id->hashPubKey);
if (NULL == entry)
return NULL;
GNUNET_CONTAINER_DLL_remove (lru_hcache_head, lru_hcache_tail, entry);
GNUNET_CONTAINER_DLL_insert_tail (lru_hcache_head, lru_hcache_tail, entry);
return entry->hello;
}
/**
* Removes the given cache entry from cache and frees its resources
*
* @param entry the entry to remove
*/
static void
GST_cache_remove (struct CacheEntry *entry)
{
GNUNET_CONTAINER_DLL_remove (lru_hcache_head, lru_hcache_tail, entry);
GNUNET_assert (GNUNET_YES ==
GNUNET_CONTAINER_multihashmap_remove (cache, &entry->key,
entry));
GNUNET_free (entry->hello);
GNUNET_free (entry);
}
/**
* Caches the HELLO of the given peer. Updates the HELLO if it was already
* cached before
*
* @param id the peer identity of the peer whose HELLO has to be cached
* @param hello the HELLO message
*/
void
GST_cache_add (const struct GNUNET_PeerIdentity *id,
const struct GNUNET_MessageHeader *hello)
{
struct CacheEntry *entry;
if (NULL == cache)
return;
entry = GNUNET_CONTAINER_multihashmap_get (cache, &id->hashPubKey);
if (NULL == entry)
{
entry = GNUNET_malloc (sizeof (struct CacheEntry));
memcpy (&entry->key, &id->hashPubKey, sizeof (struct GNUNET_HashCode));
if (GNUNET_CONTAINER_multihashmap_size (cache) == cache_size)
{
GNUNET_assert (NULL != lru_hcache_head);
GST_cache_remove (lru_hcache_head);
}
GNUNET_assert (GNUNET_OK ==
GNUNET_CONTAINER_multihashmap_put (cache, &entry->key,
entry,
GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST));
}
else
{
GNUNET_CONTAINER_DLL_remove (lru_hcache_head, lru_hcache_tail, entry);
GNUNET_free (entry->hello);
}
entry->hello = GNUNET_copy_message (hello);
GNUNET_CONTAINER_DLL_insert_tail (lru_hcache_head, lru_hcache_tail, entry);
}
/**
* Initializes the cache
*
* @param size the size of the cache
*/
void
GST_cache_init (unsigned int size)
{
if (0 == size)
return;
cache_size = size;
if (size > 1)
size = size / 2;
cache = GNUNET_CONTAINER_multihashmap_create (size, GNUNET_YES);
}
/**
* Clear cache
*/
void
GST_cache_clear ()
{
if (NULL != cache)
GNUNET_assert (GNUNET_CONTAINER_multihashmap_size (cache) <=
cache_size);
while (NULL != lru_hcache_head)
GST_cache_remove (lru_hcache_head);
if (NULL != cache)
{
GNUNET_assert (0 == GNUNET_CONTAINER_multihashmap_size (cache));
GNUNET_CONTAINER_multihashmap_destroy (cache);
}
}
/* end of gnunet-service-testbed_hc.c */
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