moving plugin headers

1 files changed, 342 insertions, 0 deletions

diff --git a/src/include/gnunet_datastore_plugin.h b/src/include/gnunet_datastore_plugin.h
new file mode 100644
index 000000000..832d53a68
--- /dev/null
+++ b/src/include/gnunet_datastore_plugin.h
@@ -0,0 +1,342 @@
+/*
+     This file is part of GNUnet
+     (C) 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 datastore/gnunet_datastore_plugin.h
+ * @brief API for the database backend plugins.
+ * @author Christian Grothoff
+ */
+#ifndef PLUGIN_DATASTORE_H
+#define PLUGIN_DATASTORE_H
+
+#include "gnunet_block_lib.h"
+#include "gnunet_configuration_lib.h"
+#include "gnunet_datastore_service.h"
+#include "gnunet_statistics_service.h"
+#include "gnunet_scheduler_lib.h"
+
+
+/**
+ * How many bytes of overhead will we assume per entry
+ * in any DB (for reservations)?
+ */
+#define GNUNET_DATASTORE_ENTRY_OVERHEAD 256
+
+
+/**
+ * Function invoked to notify service of disk utilization
+ * changes.
+ *
+ * @param cls closure
+ * @param delta change in disk utilization, 
+ *        0 for "reset to empty"
+ */
+typedef void (*DiskUtilizationChange)(void *cls,
+                                      int delta);
+
+
+/**
+ * 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_DATASTORE_PluginEnvironment
+{
+  /**
+   * Configuration to use.
+   */
+  const struct GNUNET_CONFIGURATION_Handle *cfg;
+
+  /**
+   * Function to call on disk utilization change.
+   */
+  DiskUtilizationChange duc;
+
+  /**
+   * Closure.
+   */
+  void *cls;
+
+};
+
+
+/**
+ * Function invoked on behalf of a "PluginIterator"
+ * asking the database plugin to call the iterator
+ * with the next item.
+ *
+ * @param next_cls whatever argument was given
+ *        to the PluginIterator as "next_cls".
+ * @param end_it set to GNUNET_YES if we
+ *        should terminate the iteration early
+ *        (iterator should be still called once more
+ *         to signal the end of the iteration).
+ */
+typedef void (*PluginNextRequest)(void *next_cls,
+                                  int end_it);
+
+
+/**
+ * An iterator over a set of items stored in the datastore.
+ *
+ * @param cls closure
+ * @param next_cls closure to pass to the "next" function.
+ * @param key key for the content
+ * @param size number of bytes in data
+ * @param data content stored
+ * @param type type of the content
+ * @param priority priority of the content
+ * @param anonymity anonymity-level for the content
+ * @param expiration expiration time for the content
+ * @param uid unique identifier for the datum;
+ *        maybe 0 if no unique identifier is available
+ *
+ * @return GNUNET_SYSERR to abort the iteration, GNUNET_OK to continue
+ *         (continue on call to "next", of course),
+ *         GNUNET_NO to delete the item and continue (if supported)
+ */
+typedef int (*PluginIterator) (void *cls,
+                               void *next_cls,
+                               const GNUNET_HashCode * key,
+                               uint32_t size,
+                               const void *data,
+                               enum GNUNET_BLOCK_Type type,
+                               uint32_t priority,
+                               uint32_t anonymity,
+                               struct GNUNET_TIME_Absolute
+                               expiration, 
+                               uint64_t uid);
+
+/**
+ * Get an estimate of how much space the database is
+ * currently using.
+ *
+ * @param cls closure
+ * @return number of bytes used on disk
+ */
+typedef unsigned long long (*PluginGetSize) (void *cls);
+
+
+/**
+ * Store an item in the datastore.  If the item is already present,
+ * the priorities are summed up and the higher expiration time and
+ * lower anonymity level is used.
+ *
+ * @param cls closure
+ * @param key key for the item
+ * @param size number of bytes in data
+ * @param data content stored
+ * @param type type of the content
+ * @param priority priority of the content
+ * @param anonymity anonymity-level for the content
+ * @param expiration expiration time for the content
+ * @param msg set to an error message (on failure)
+ * @return GNUNET_OK on success, GNUNET_NO if the content
+ *         was already present (and may have been updated);
+ *         GNUNET_SYSERR on failure
+ */
+typedef int (*PluginPut) (void *cls,
+                          const GNUNET_HashCode * key,
+                          uint32_t size,
+                          const void *data,
+                          enum GNUNET_BLOCK_Type type,
+                          uint32_t priority,
+                          uint32_t anonymity,
+                          struct GNUNET_TIME_Absolute expiration,
+                           char **msg);
+
+
+/**
+ * Iterate over the results for a particular key
+ * in the datastore.
+ *
+ * @param cls closure
+ * @param key maybe NULL (to match all entries)
+ * @param vhash hash of the value, maybe NULL (to
+ *        match all values that have the right key).
+ *        Note that for DBlocks there is no difference
+ *        betwen key and vhash, but for other blocks
+ *        there may be!
+ * @param type entries of which type are relevant?
+ *     Use 0 for any type.
+ * @param iter function to call on each matching value; however,
+ *        after the first call to "iter", the plugin must wait
+ *        until "NextRequest" was called before giving the iterator
+ *        the next item; finally, the "iter" should be called once
+ *        once with a NULL value at the end ("next_cls" should be NULL
+ *        for that last call)
+ * @param iter_cls closure for iter
+ */
+typedef void (*PluginGet) (void *cls,
+                           const GNUNET_HashCode * key,
+                           const GNUNET_HashCode * vhash,
+                           enum GNUNET_BLOCK_Type type,
+                           PluginIterator iter, void *iter_cls);
+
+
+/**
+ * Update the priority for a particular key in the datastore.  If
+ * the expiration time in value is different than the time found in
+ * the datastore, the higher value should be kept.  For the
+ * anonymity level, the lower value is to be used.  The specified
+ * priority should be added to the existing priority, ignoring the
+ * priority in value.
+ *
+ * Note that it is possible for multiple values to match this put.
+ * In that case, all of the respective values are updated.
+ *
+ * @param cls closure
+ * @param uid unique identifier of the datum
+ * @param delta by how much should the priority
+ *     change?  If priority + delta < 0 the
+ *     priority should be set to 0 (never go
+ *     negative).
+ * @param expire new expiration time should be the
+ *     MAX of any existing expiration time and
+ *     this value
+ * @param msg set to an error message (on error)
+ * @return GNUNET_OK on success
+ */
+typedef int (*PluginUpdate) (void *cls,
+                             uint64_t uid,
+                             int delta, struct GNUNET_TIME_Absolute expire,
+                             char **msg);
+
+
+/**
+ * Select a subset of the items in the datastore and call
+ * the given iterator for each of them.
+ *
+ * @param cls closure
+ * @param type entries of which type should be considered?
+ *        Use 0 for any type.
+ * @param iter function to call on each matching value; however,
+ *        after the first call to "iter", the plugin must wait
+ *        until "NextRequest" was called before giving the iterator
+ *        the next item; finally, the "iter" should be called once
+ *        once with a NULL value at the end ("next_cls" should be NULL
+ *        for that last call)
+ * @param iter_cls closure for iter
+ */
+typedef void (*PluginSelector) (void *cls,
+                                enum GNUNET_BLOCK_Type type,
+                                PluginIterator iter,
+                                void *iter_cls);
+
+/**
+ * Drop database.
+ *
+ * @param cls closure
+ */
+typedef void (*PluginDrop) (void *cls);
+
+
+
+/**
+ * Each plugin is required to return a pointer to a struct of this
+ * type as the return value from its entry point.
+ */
+struct GNUNET_DATASTORE_PluginFunctions
+{
+
+  /**
+   * Closure to use for all of the following callbacks
+   * (except "next_request").
+   */
+  void *cls;
+
+  /**
+   * Get the current on-disk size of the SQ store.  Estimates are
+   * fine, if that's the only thing available.
+   */
+  PluginGetSize get_size;
+
+  /**
+   * Function to store an item in the datastore.
+   */
+  PluginPut put;
+
+  /**
+   * Function called by iterators whenever they want the next value;
+   * note that unlike all of the other callbacks, this one does get a
+   * the "next_cls" closure which is usually different from the "cls"
+   * member of this struct!
+   */
+  PluginNextRequest next_request;
+
+  /**
+   * Function to iterate over the results for a particular key
+   * in the datastore.
+   */
+  PluginGet get;
+
+  /**
+   * Update the priority for a particular key in the datastore.  If
+   * the expiration time in value is different than the time found in
+   * the datastore, the higher value should be kept.  For the
+   * anonymity level, the lower value is to be used.  The specified
+   * priority should be added to the existing priority, ignoring the
+   * priority in value.
+   */
+  PluginUpdate update;
+
+  /**
+   * Iterate over the items in the datastore in ascending
+   * order of priority.
+   */
+  PluginSelector iter_low_priority;
+
+  /**
+   * Iterate over content with anonymity zero.
+   */
+  PluginSelector iter_zero_anonymity;
+
+  /**
+   * Iterate over the items in the datastore in ascending order of
+   * expiration time. 
+   */
+  PluginSelector iter_ascending_expiration;
+
+  /**
+   * Iterate over the items in the datastore in migration
+   * order.  Call the given function on the next item only
+   * (and then signal 'end' with a second call).  This is
+   * a significant difference from all the other iterators!
+   */
+  PluginSelector iter_migration_order;
+
+  /**
+   * Iterate over all the items in the datastore
+   * as fast as possible in a single transaction
+   * (can lock datastore while this happens, focus
+   * is on doing it fast).
+   */
+  PluginSelector iter_all_now;
+
+  /**
+   * Delete the database.  The next operation is
+   * guaranteed to be unloading of the module.
+   */
+  PluginDrop drop;
+
+};
+
+
+#endif