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+/*
+ This file is part of GNUnet
+ (C) 2006, 2009 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 include/gnunet_datacache_plugin.h
+ * @brief API for database backends for the datacache
+ * @author Christian Grothoff
+ */
+#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 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 size number of bytes in data
+ * @param data data to store
+ * @param type type of the value
+ * @param discard_time when to discard the value in any case
+ * @return 0 on error, number of bytes used otherwise
+ */
+ size_t (*put) (void *cls, const GNUNET_HashCode * key, size_t size,
+ const char *data, enum GNUNET_BLOCK_Type type,
+ struct GNUNET_TIME_Absolute discard_time);
+
+
+ /**
+ * Iterate over the results for a particular key
+ * in the datastore.
+ *
+ * @param cls closure (internal context for the plugin)
+ * @param key
+ * @param type entries of which type are relevant?
+ * @param iter maybe NULL (to just count)
+ * @param iter_cls closure for iter
+ * @return the number of results found
+ */
+ unsigned int (*get) (void *cls, const 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);
+
+
+};
+
+
+#if 0 /* keep Emacsens' auto-indent happy */
+{
+#endif
+#ifdef __cplusplus
+}
+#endif
+
+/* end of gnunet_datacache_plugin.h */
+#endif