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1/*
2 This file is part of GNUnet
3 (C) 2009 Christian Grothoff (and other contributing authors)
4
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 2, or (at your
8 option) any later version.
9
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA.
19*/
20
21/**
22 * @file datastore/plugin_datastore.h
23 * @brief API for the database backend plugins.
24 * @author Christian Grothoff
25 *
26 * TODO:
27 * - consider defining enumeration or at least typedef
28 * for the type of "type" (instead of using uint32_t)
29 */
30#ifndef PLUGIN_DATASTORE_H
31#define PLUGIN_DATASTORE_H
32
33#include "gnunet_configuration_lib.h"
34#include "gnunet_scheduler_lib.h"
35#include "gnunet_datastore_service.h"
36
37/**
38 * The datastore service will pass a pointer to a struct
39 * of this type as the first and only argument to the
40 * entry point of each datastore plugin.
41 */
42struct GNUNET_DATASTORE_PluginEnvironment
43{
44 /**
45 * Configuration to use.
46 */
47 struct GNUNET_CONFIGURATION_Handle *cfg;
48
49 /**
50 * Scheduler to use.
51 */
52 struct GNUNET_SCHEDULER_Handle *sched;
53
54};
55
56
57/**
58 * Get an estimate of how much space the database is
59 * currently using.
60 * @return number of bytes used on disk
61 */
62typedef unsigned long long (*GNUNET_DATASTORE_GetSize) (void *cls);
63
64
65/**
66 * Store an item in the datastore.
67 *
68 * @param cls closure
69 * @param key key for the item
70 * @param size number of bytes in data
71 * @param data content stored
72 * @param type type of the content
73 * @param priority priority of the content
74 * @param anonymity anonymity-level for the content
75 * @param expiration expiration time for the content
76 */
77typedef void
78 (*GNUNET_DATASTORE_Put) (void *cls,
79 const GNUNET_HashCode * key,
80 uint32_t size,
81 const void *data,
82 unit32_t type,
83 uint32_t priority,
84 uint32_t anonymity,
85 struct GNUNET_TIME_Absolute expiration);
86
87
88/**
89 * Iterate over the results for a particular key
90 * in the datastore.
91 *
92 * @param cls closure
93 * @param key maybe NULL (to match all entries)
94 * @param vhash hash of the value, maybe NULL (to
95 * match all values that have the right key).
96 * Note that for DBlocks there is no difference
97 * betwen key and vhash, but for other blocks
98 * there may be!
99 * @param type entries of which type are relevant?
100 * Use 0 for any type.
101 * @param iter function to call on each matching value;
102 * will be called once with a NULL value at the end
103 * @param iter_cls closure for iter
104 */
105typedef void
106 (*GNUNET_DATASTORE_Get) (void *cls,
107 const GNUNET_HashCode * key,
108 const GNUNET_HashCode * vhash,
109 uint32_t type,
110 GNUNET_DATASTORE_Iterator iter, void *iter_cls);
111
112
113/**
114 * Update the priority for a particular key in the datastore. If
115 * the expiration time in value is different than the time found in
116 * the datastore, the higher value should be kept. For the
117 * anonymity level, the lower value is to be used. The specified
118 * priority should be added to the existing priority, ignoring the
119 * priority in value.
120 *
121 * Note that it is possible for multiple values to match this put.
122 * In that case, all of the respective values are updated.
123 *
124 * @param uid unique identifier of the datum
125 * @param delta by how much should the priority
126 * change? If priority + delta < 0 the
127 * priority should be set to 0 (never go
128 * negative).
129 * @param expire new expiration time should be the
130 * MAX of any existing expiration time and
131 * this value
132 */
133typedef void
134 (*GNUNET_DATASTORE_Update) (void *cls,
135 unsigned long long uid,
136 int delta, struct GNUNET_TIME_Absolute expire);
137
138
139/**
140 * Select a subset of the items in the datastore and call
141 * the given iterator for each of them.
142 *
143 * @param type entries of which type should be considered?
144 * Use 0 for any type.
145 * @param iter function to call on each matching value;
146 * will be called once with a NULL value at the end
147 * @param iter_cls closure for iter
148 */
149typedef void
150 (*GNUNET_DATASTORE_Selector) (void *cls,
151 uint32_t type,
152 GNUNET_DATASTORE_Iterator iter,
153 void *iter_cls);
154
155/**
156 * Drop database.
157 */
158typedef void (*GNUNET_DATASTORE_Drop) (void *cls);
159
160
161
162/**
163 * Each plugin is required to return a pointer to a struct of this
164 * type as the return value from its entry point.
165 */
166struct GNUNET_DATASTORE_PluginFunctions
167{
168
169 /**
170 * Closure to use for all of the following callbacks.
171 */
172 void *cls;
173
174 /**
175 * Get the current on-disk size of the SQ store. Estimates are
176 * fine, if that's the only thing available.
177 */
178 GNUNET_DATASTORE_GetSize size;
179
180 /**
181 * Function to store an item in the datastore.
182 */
183 GNUNET_DATASTORE_Put put;
184
185 /**
186 * Function to iterate over the results for a particular key
187 * in the datastore.
188 */
189 GNUNET_DATASTORE_Get get;
190
191 /**
192 * Update the priority for a particular key in the datastore. If
193 * the expiration time in value is different than the time found in
194 * the datastore, the higher value should be kept. For the
195 * anonymity level, the lower value is to be used. The specified
196 * priority should be added to the existing priority, ignoring the
197 * priority in value.
198 */
199 GNUNET_DATASTORE_Update update;
200
201 /**
202 * Iterate over the items in the datastore in ascending
203 * order of priority.
204 */
205 GNUNET_DATASTORE_Selector iter_low_priority;
206
207 /**
208 * Iterate over content with anonymity zero.
209 */
210 GNUNET_DATASTORE_Selector iter_zero_anonymity;
211
212 /**
213 * Iterate over the items in the datastore in ascending
214 * order of expiration time.
215 */
216 GNUNET_DATSTORE_Selector iter_ascending_expiration;
217
218 /**
219 * Iterate over the items in the datastore in migration
220 * order.
221 */
222 GNUNET_DATASTORE_Selector iter_migration_order;
223
224 /**
225 * Iterate over all the items in the datastore
226 * as fast as possible in a single transaction
227 * (can lock datastore while this happens, focus
228 * is on doing it fast).
229 */
230 GNUNET_DATASTORE_Selector iter_all_now;
231
232 /**
233 * Delete the database. The next operation is
234 * guaranteed to be unloading of the module.
235 */
236 GNUNET_DATASTORE_Drop drop;
237
238};
239
240
241#endif