1 /* database.cc: Database::Internal base class.
2 *
3 * Copyright 1999,2000,2001 BrightStation PLC
4 * Copyright 2002 Ananova Ltd
5 * Copyright 2002,2003,2004,2005,2006,2007,2008,2009,2011,2014,2016 Olly Betts
6 * Copyright 2008 Lemur Consulting Ltd
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the
11 * License, or (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
21 * USA
22 */
23
24 #include <config.h>
25
26 #include "database.h"
27
28 #include "xapian/error.h"
29
30 #include "api/leafpostlist.h"
31 #include "omassert.h"
32 #include "slowvaluelist.h"
33
34 #include <algorithm>
35 #include <string>
36
37 using namespace std;
38 using Xapian::Internal::intrusive_ptr;
39
40 namespace Xapian {
41
~Internal()42 Database::Internal::~Internal()
43 {
44 }
45
46 void
keep_alive()47 Database::Internal::keep_alive()
48 {
49 // For the normal case of local databases, nothing needs to be done.
50 }
51
52
53 void
readahead_for_query(const Xapian::Query &)54 Database::Internal::readahead_for_query(const Xapian::Query &)
55 {
56 }
57
58 Xapian::termcount
get_doclength_lower_bound() const59 Database::Internal::get_doclength_lower_bound() const
60 {
61 // A zero-length document can't contain any terms, so we ignore such
62 // documents for the purposes of this lower bound.
63 return 1;
64 }
65
66 Xapian::termcount
get_doclength_upper_bound() const67 Database::Internal::get_doclength_upper_bound() const
68 {
69 // Not a very tight bound in general, but this is only a fall-back for
70 // backends which don't store these stats.
71 return min(get_total_length(), Xapian::totallength(Xapian::termcount(-1)));
72 }
73
74 Xapian::termcount
get_wdf_upper_bound(const string & term) const75 Database::Internal::get_wdf_upper_bound(const string & term) const
76 {
77 // Not a very tight bound in general, but this is only a fall-back for
78 // backends which don't store these stats.
79 Xapian::termcount cf;
80 get_freqs(term, NULL, &cf);
81 return cf;
82 }
83
84 // Discard any exceptions - we're called from the destructors of derived
85 // classes so we can't safely throw.
86 void
dtor_called()87 Database::Internal::dtor_called()
88 {
89 try {
90 if (transaction_active()) {
91 cancel_transaction();
92 } else if (transaction_state == TRANSACTION_NONE) {
93 commit();
94 }
95 } catch (...) {
96 // We can't safely throw exceptions from a destructor in case an
97 // exception is already active and causing us to be destroyed.
98 }
99 }
100
101 void
commit()102 Database::Internal::commit()
103 {
104 // Writable databases should override this method.
105 Assert(false);
106 }
107
108 void
cancel()109 Database::Internal::cancel()
110 {
111 // Writable databases should override this method.
112 Assert(false);
113 }
114
115 void
begin_transaction(bool flushed)116 Database::Internal::begin_transaction(bool flushed)
117 {
118 if (transaction_state != TRANSACTION_NONE) {
119 if (transaction_state == TRANSACTION_UNIMPLEMENTED)
120 throw Xapian::UnimplementedError("This backend doesn't implement transactions");
121 throw InvalidOperationError("Cannot begin transaction - transaction already in progress");
122 }
123 if (flushed) {
124 // N.B. Call commit() before we set transaction_state since commit()
125 // isn't allowing during a transaction.
126 commit();
127 transaction_state = TRANSACTION_FLUSHED;
128 } else {
129 transaction_state = TRANSACTION_UNFLUSHED;
130 }
131 }
132
133 void
commit_transaction()134 Database::Internal::commit_transaction()
135 {
136 if (!transaction_active()) {
137 if (transaction_state == TRANSACTION_UNIMPLEMENTED)
138 throw Xapian::UnimplementedError("This backend doesn't implement transactions");
139 throw InvalidOperationError("Cannot commit transaction - no transaction currently in progress");
140 }
141 bool flushed = (transaction_state == TRANSACTION_FLUSHED);
142 transaction_state = TRANSACTION_NONE;
143 // N.B. Call commit() after we clear transaction_state since commit()
144 // isn't allowing during a transaction.
145 if (flushed) commit();
146 }
147
148 void
cancel_transaction()149 Database::Internal::cancel_transaction()
150 {
151 if (!transaction_active()) {
152 if (transaction_state == TRANSACTION_UNIMPLEMENTED)
153 throw Xapian::UnimplementedError("This backend doesn't implement transactions");
154 throw InvalidOperationError("Cannot cancel transaction - no transaction currently in progress");
155 }
156 transaction_state = TRANSACTION_NONE;
157 cancel();
158 }
159
160 Xapian::docid
add_document(const Xapian::Document &)161 Database::Internal::add_document(const Xapian::Document &)
162 {
163 // Writable databases should override this method.
164 Assert(false);
165 return 0;
166 }
167
168 void
delete_document(Xapian::docid)169 Database::Internal::delete_document(Xapian::docid)
170 {
171 // Writable databases should override this method.
172 Assert(false);
173 }
174
175 void
delete_document(const string & unique_term)176 Database::Internal::delete_document(const string & unique_term)
177 {
178 // Default implementation - overridden for remote databases
179 intrusive_ptr<LeafPostList> pl(open_post_list(unique_term));
180 while (pl->next(), !pl->at_end()) {
181 delete_document(pl->get_docid());
182 }
183 }
184
185 void
replace_document(Xapian::docid,const Xapian::Document &)186 Database::Internal::replace_document(Xapian::docid, const Xapian::Document &)
187 {
188 // Writable databases should override this method.
189 Assert(false);
190 }
191
192 Xapian::docid
replace_document(const string & unique_term,const Xapian::Document & document)193 Database::Internal::replace_document(const string & unique_term,
194 const Xapian::Document & document)
195 {
196 // Default implementation - overridden for remote databases
197 intrusive_ptr<LeafPostList> pl(open_post_list(unique_term));
198 pl->next();
199 if (pl->at_end()) {
200 return add_document(document);
201 }
202 Xapian::docid did = pl->get_docid();
203 replace_document(did, document);
204 while (pl->next(), !pl->at_end()) {
205 delete_document(pl->get_docid());
206 }
207 return did;
208 }
209
210 ValueList *
open_value_list(Xapian::valueno slot) const211 Database::Internal::open_value_list(Xapian::valueno slot) const
212 {
213 return new SlowValueList(this, slot);
214 }
215
216 TermList *
open_spelling_termlist(const string &) const217 Database::Internal::open_spelling_termlist(const string &) const
218 {
219 // Only implemented for some database backends - others will just not
220 // suggest spelling corrections (or not contribute to them in a multiple
221 // database situation).
222 return NULL;
223 }
224
225 TermList *
open_spelling_wordlist() const226 Database::Internal::open_spelling_wordlist() const
227 {
228 // Only implemented for some database backends - others will just not
229 // suggest spelling corrections (or not contribute to them in a multiple
230 // database situation).
231 return NULL;
232 }
233
234 Xapian::doccount
get_spelling_frequency(const string &) const235 Database::Internal::get_spelling_frequency(const string &) const
236 {
237 // Only implemented for some database backends - others will just not
238 // suggest spelling corrections (or not contribute to them in a multiple
239 // database situation).
240 return 0;
241 }
242
243 void
add_spelling(const string &,Xapian::termcount) const244 Database::Internal::add_spelling(const string &, Xapian::termcount) const
245 {
246 throw Xapian::UnimplementedError("This backend doesn't implement spelling correction");
247 }
248
249 void
remove_spelling(const string &,Xapian::termcount) const250 Database::Internal::remove_spelling(const string &, Xapian::termcount) const
251 {
252 throw Xapian::UnimplementedError("This backend doesn't implement spelling correction");
253 }
254
255 TermList *
open_synonym_termlist(const string &) const256 Database::Internal::open_synonym_termlist(const string &) const
257 {
258 // Only implemented for some database backends - others will just not
259 // expand synonyms (or not contribute to them in a multiple database
260 // situation).
261 return NULL;
262 }
263
264 TermList *
open_synonym_keylist(const string &) const265 Database::Internal::open_synonym_keylist(const string &) const
266 {
267 // Only implemented for some database backends - others will just not
268 // expand synonyms (or not contribute to them in a multiple database
269 // situation).
270 return NULL;
271 }
272
273 void
add_synonym(const string &,const string &) const274 Database::Internal::add_synonym(const string &, const string &) const
275 {
276 throw Xapian::UnimplementedError("This backend doesn't implement synonyms");
277 }
278
279 void
remove_synonym(const string &,const string &) const280 Database::Internal::remove_synonym(const string &, const string &) const
281 {
282 throw Xapian::UnimplementedError("This backend doesn't implement synonyms");
283 }
284
285 void
clear_synonyms(const string &) const286 Database::Internal::clear_synonyms(const string &) const
287 {
288 throw Xapian::UnimplementedError("This backend doesn't implement synonyms");
289 }
290
291 string
get_metadata(const string &) const292 Database::Internal::get_metadata(const string &) const
293 {
294 return string();
295 }
296
297 TermList *
open_metadata_keylist(const string &) const298 Database::Internal::open_metadata_keylist(const string &) const
299 {
300 // Only implemented for some database backends - others will simply report
301 // there being no metadata keys.
302 return NULL;
303 }
304
305 void
set_metadata(const string &,const string &)306 Database::Internal::set_metadata(const string &, const string &)
307 {
308 throw Xapian::UnimplementedError("This backend doesn't implement metadata");
309 }
310
311 bool
reopen()312 Database::Internal::reopen()
313 {
314 // Database backends which don't support simultaneous update and reading
315 // probably don't need to do anything here. And since we didn't do
316 // anything we should return false to indicate that nothing has changed.
317 return false;
318 }
319
320 void
request_document(Xapian::docid) const321 Database::Internal::request_document(Xapian::docid /*did*/) const
322 {
323 }
324
325 Xapian::Document::Internal *
collect_document(Xapian::docid did) const326 Database::Internal::collect_document(Xapian::docid did) const
327 {
328 // Open the document lazily - collect document is only called by
329 // Enquire::Internal::read_doc() for a given MSetItem, so we know that the
330 // document already exists.
331 return open_document(did, true);
332 }
333
334 void
write_changesets_to_fd(int,const string &,bool,ReplicationInfo *)335 Database::Internal::write_changesets_to_fd(int, const string &, bool, ReplicationInfo *)
336 {
337 throw Xapian::UnimplementedError("This backend doesn't provide changesets");
338 }
339
340 string
get_revision_info() const341 Database::Internal::get_revision_info() const
342 {
343 throw Xapian::UnimplementedError("This backend doesn't provide access to revision information");
344 }
345
346 string
get_uuid() const347 Database::Internal::get_uuid() const
348 {
349 return string();
350 }
351
352 void
invalidate_doc_object(Xapian::Document::Internal *) const353 Database::Internal::invalidate_doc_object(Xapian::Document::Internal *) const
354 {
355 // Do nothing, by default.
356 }
357
358 void
get_used_docid_range(Xapian::docid &,Xapian::docid &) const359 Database::Internal::get_used_docid_range(Xapian::docid &,
360 Xapian::docid &) const
361 {
362 throw Xapian::UnimplementedError("This backend doesn't implement get_used_docid_range()");
363 }
364
365 bool
locked() const366 Database::Internal::locked() const
367 {
368 return false;
369 }
370
371 }
372