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/*
This file is part of GNUnet
Copyright (C) 2006, 2009, 2015, 2022 GNUnet e.V.
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU Affero General Public License as published
by the Free Software Foundation, either version 3 of the License,
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
Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
SPDX-License-Identifier: AGPL3.0-or-later
*/
/**
* @addtogroup dht_libs DHT and support libraries
* @{
*
* @author Christian Grothoff
*
* @file
* datacache API
*
* @defgroup datacache Data Cache library
* Simple, transient hash table of bounded size with content expiration.
*
* In contrast to the sqstore there is
* no prioritization, deletion or iteration.
* All of the data is discarded when the peer shuts down!
*
* @{
*/
#ifndef GNUNET_DATACACHE_LIB_H
#define GNUNET_DATACACHE_LIB_H
#include "gnunet_util_lib.h"
#include "gnunet_block_lib.h"
#include "gnunet_dht_service.h"
#ifdef __cplusplus
extern "C"
{
#if 0 /* keep Emacsens' auto-indent happy */
}
#endif
#endif
/**
* Information about a block stored in the datacache.
*/
struct GNUNET_DATACACHE_Block
{
/**
* Key of the block.
*/
struct GNUNET_HashCode key;
/**
* When does the block expire?
*/
struct GNUNET_TIME_Absolute expiration_time;
/**
* If the path was truncated, this is the peer
* ID at which the path was truncated.
*/
struct GNUNET_PeerIdentity trunc_peer;
/**
* PUT path taken by the block, array of peer identities.
*/
const struct GNUNET_DHT_PathElement *put_path;
/**
* Actual block data.
*/
const void *data;
/**
* Number of bytes in @a data.
*/
size_t data_size;
/**
* Length of the @e put_path array.
*/
unsigned int put_path_length;
/**
* Type of the block.
*/
enum GNUNET_BLOCK_Type type;
/**
* Options for routing for the block.
*/
enum GNUNET_DHT_RouteOption ro;
};
/**
* Handle to the cache.
*/
struct GNUNET_DATACACHE_Handle;
/**
* Create a data cache.
*
* @param cfg configuration to use
* @param section section in the configuration that contains our options
* @return handle to use to access the service
*/
struct GNUNET_DATACACHE_Handle *
GNUNET_DATACACHE_create (const struct GNUNET_CONFIGURATION_Handle *cfg,
const char *section);
/**
* Destroy a data cache (and free associated resources).
*
* @param h handle to the datastore
*/
void
GNUNET_DATACACHE_destroy (struct GNUNET_DATACACHE_Handle *h);
/**
* An iterator over a set of items stored in the datacache.
*
* @param cls closure
* @param block a block from the datacache
* @return #GNUNET_OK to continue iterating, #GNUNET_SYSERR to abort
*/
typedef enum GNUNET_GenericReturnValue
(*GNUNET_DATACACHE_Iterator)(void *cls,
const struct GNUNET_DATACACHE_Block *block);
/**
* Store an item in the datacache.
*
* @param h handle to the datacache
* @param xor_distance how close is the block's key to our pid?
* @param block actual block data to store
* @return #GNUNET_OK on success, #GNUNET_SYSERR on error, #GNUNET_NO if duplicate
*/
enum GNUNET_GenericReturnValue
GNUNET_DATACACHE_put (struct GNUNET_DATACACHE_Handle *h,
uint32_t xor_distance,
const struct GNUNET_DATACACHE_Block *block);
/**
* Iterate over the results for a particular key
* in the datacache.
*
* @param h handle to the datacache
* @param key what to look up
* @param type entries of which type are relevant?
* @param iter maybe NULL (to just count)
* @param iter_cls closure for @a iter
* @return the number of results found
*/
unsigned int
GNUNET_DATACACHE_get (struct GNUNET_DATACACHE_Handle *h,
const struct GNUNET_HashCode *key,
enum GNUNET_BLOCK_Type type,
GNUNET_DATACACHE_Iterator iter,
void *iter_cls);
/**
* Iterate over the results that are "close" to a particular key in
* the datacache. "close" is defined as numerically larger than @a
* key (when interpreted as a circular address space), with small
* distance.
*
* @param h handle to the datacache
* @param key area of the keyspace to look into
* @param type entries of which type are relevant?
* @param num_results number of results that should be returned to @a iter
* @param iter maybe NULL (to just count)
* @param iter_cls closure for @a iter
* @return the number of results found
*/
unsigned int
GNUNET_DATACACHE_get_closest (struct GNUNET_DATACACHE_Handle *h,
const struct GNUNET_HashCode *key,
enum GNUNET_BLOCK_Type type,
unsigned int num_results,
GNUNET_DATACACHE_Iterator iter,
void *iter_cls);
#if 0 /* keep Emacsens' auto-indent happy */
{
#endif
#ifdef __cplusplus
}
#endif
#endif
/** @} */ /* end of group */
/** @} */ /* end of group addition */
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