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/*
This file is part of GNUnet
Copyright (C) 2006, 2009, 2015 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.
*/
/**
* @author Christian Grothoff
*
* @file
* API for database backends for the datacache
*
* @defgroup datacache-plugin Data Cache plugin API
* API for database backends for the datacache
* @{
*/
#ifndef PLUGIN_DATACACHE_H
#define PLUGIN_DATACACHE_H
#include "gnunet_datacache_lib.h"
#ifdef __cplusplus
extern "C"
{
#if 0 /* keep Emacsens' auto-indent happy */
}
#endif
#endif
/**
* Function called by plugins to notify the datacache
* about content deletions.
*
* @param cls closure
* @param key key of the content that was deleted
* @param size number of bytes that were made available
*/
typedef void
(*GNUNET_DATACACHE_DeleteNotifyCallback) (void *cls,
const struct GNUNET_HashCode *key,
size_t size);
/**
* The datastore service will pass a pointer to a struct
* of this type as the first and only argument to the
* entry point of each datastore plugin.
*/
struct GNUNET_DATACACHE_PluginEnvironment
{
/**
* Configuration to use.
*/
const struct GNUNET_CONFIGURATION_Handle *cfg;
/**
* Configuration section to use.
*/
const char *section;
/**
* Closure to use for callbacks.
*/
void *cls;
/**
* Function to call whenever the plugin needs to
* discard content that it was asked to store.
*/
GNUNET_DATACACHE_DeleteNotifyCallback delete_notify;
/**
* How much space are we allowed to use?
*/
unsigned long long quota;
};
/**
* @brief struct returned by the initialization function of the plugin
*/
struct GNUNET_DATACACHE_PluginFunctions
{
/**
* Closure to pass to all plugin functions.
*/
void *cls;
/**
* Store an item in the datastore.
*
* @param cls closure (internal context for the plugin)
* @param key key to store the value under
* @param xor_distance how close is @a key to our PID?
* @param size number of bytes in @a data
* @param data data to store
* @param type type of the value
* @param discard_time when to discard the value in any case
* @param path_info_len number of entries in @a path_info
* @param path_info a path through the network
* @return 0 if duplicate, -1 on error, number of bytes used otherwise
*/
ssize_t (*put) (void *cls,
const struct GNUNET_HashCode *key,
uint32_t xor_distance,
size_t size,
const char *data,
enum GNUNET_BLOCK_Type type,
struct GNUNET_TIME_Absolute discard_time,
unsigned int path_info_len,
const struct GNUNET_PeerIdentity *path_info);
/**
* Iterate over the results for a particular key
* in the datastore.
*
* @param cls closure (internal context for the plugin)
* @param key key to look for
* @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 (*get) (void *cls,
const struct GNUNET_HashCode *key,
enum GNUNET_BLOCK_Type type,
GNUNET_DATACACHE_Iterator iter,
void *iter_cls);
/**
* Delete the entry with the lowest expiration value
* from the datacache right now.
*
* @param cls closure (internal context for the plugin)
* @return #GNUNET_OK on success, #GNUNET_SYSERR on error
*/
int (*del) (void *cls);
/**
* Return a random value from the datastore.
*
* @param cls closure (internal context for the plugin)
* @param iter maybe NULL (to just count)
* @param iter_cls closure for @a iter
* @return the number of results found (zero or one)
*/
unsigned int (*get_random) (void *cls,
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 cls closure (internal context for the plugin)
* @param key area of the keyspace to look into
* @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 (*get_closest) (void *cls,
const struct GNUNET_HashCode *key,
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 */
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