towards datacache implementation

1 files changed, 159 insertions, 0 deletions

diff --git a/src/datacache/plugin_datacache.h b/src/datacache/plugin_datacache.h
new file mode 100644
index 000000000..e099cd31d
--- /dev/null
+++ b/src/datacache/plugin_datacache.h
@@ -0,0 +1,159 @@
+/*
+     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 datacache/plugin_datacache.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,
+                                                      uint32_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
+{
+  
+  /**
+   * Scheduler to use.
+   */ 
+  struct GNUNET_SCHEDULER_Handle *sched;
+
+  /**
+   * Configuration to use.
+   */
+  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 key key to store data under
+   * @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
+   */
+  uint32_t (*put) (void *cls,
+                   const GNUNET_HashCode * key,
+                   uint32_t size,
+                   const char *data,
+                   uint32_t type,
+                   struct GNUNET_TIME_Absolute discard_time);
+
+
+  /**
+   * Iterate over the results for a particular key
+   * in the datastore.
+   *
+   * @param key
+   * @param type entries of which type are relevant?
+   * @param iter maybe NULL (to just count)
+   * @return the number of results found
+   */
+  unsigned int (*get) (void *cls,
+                       const GNUNET_HashCode * key,
+                       uint32_t type,
+                       GNUNET_DATACACHE_Iterator iter,
+                       void *iter_cls);
+
+
+  /**
+   * Delete the entry with the lowest expiration value
+   * from the datacache right now.
+   * 
+   * @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 plugin_datacache.h */
+#endif