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   1 /* query.cc - Support for searching a notmuch database
   2  *
   3  * Copyright © 2009 Carl Worth
   4  *
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation, either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see https://www.gnu.org/licenses/ .
  17  *
  18  * Author: Carl Worth <cworth@cworth.org>
  19  */
  20
  21 #include "notmuch-private.h"
  22 #include "database-private.h"
  23
  24 #include <glib.h> /* GHashTable, GPtrArray */
  25
  26 struct _notmuch_query {
  27     notmuch_database_t *notmuch;
  28     const char *query_string;
  29     notmuch_sort_t sort;
  30     notmuch_string_list_t *exclude_terms;
  31     notmuch_exclude_t omit_excluded;
  32     notmuch_bool_t parsed;
  33     Xapian::Query xapian_query;
  34     std::set<std::string> terms;
  35 };
  36
  37 typedef struct _notmuch_mset_messages {
  38     notmuch_messages_t base;
  39     notmuch_database_t *notmuch;
  40     Xapian::MSetIterator iterator;
  41     Xapian::MSetIterator iterator_end;
  42 } notmuch_mset_messages_t;
  43
  44 struct _notmuch_doc_id_set {
  45     unsigned char *bitmap;
  46     unsigned int bound;
  47 };
  48
  49 #define DOCIDSET_WORD(bit) ((bit) / CHAR_BIT)
  50 #define DOCIDSET_BIT(bit) ((bit) % CHAR_BIT)
  51
  52 struct visible _notmuch_threads {
  53     notmuch_query_t *query;
  54
  55     /* The ordered list of doc ids matched by the query. */
  56     GArray *doc_ids;
  57     /* Our iterator's current position in doc_ids. */
  58     unsigned int doc_id_pos;
  59     /* The set of matched docid's that have not been assigned to a
  60      * thread. Initially, this contains every docid in doc_ids. */
  61     notmuch_doc_id_set_t match_set;
  62 };
  63
  64 /* We need this in the message functions so forward declare. */
  65 static notmuch_bool_t
  66 _notmuch_doc_id_set_init (void *ctx,
  67                           notmuch_doc_id_set_t *doc_ids,
  68                           GArray *arr);
  69
  70 static notmuch_bool_t
  71 _debug_query (void)
  72 {
  73     char *env = getenv ("NOTMUCH_DEBUG_QUERY");
  74     return (env && strcmp (env, "") != 0);
  75 }
  76
  77 /* Explicit destructor call for placement new */
  78 static int
  79 _notmuch_query_destructor (notmuch_query_t *query) {
  80     query->xapian_query.~Query();
  81     query->terms.~set<std::string>();
  82     return 0;
  83 }
  84
  85 notmuch_query_t *
  86 notmuch_query_create (notmuch_database_t *notmuch,
  87                       const char *query_string)
  88 {
  89     notmuch_query_t *query;
  90
  91     if (_debug_query ())
  92         fprintf (stderr, "Query string is:\n%s\n", query_string);
  93
  94     query = talloc (notmuch, notmuch_query_t);
  95     if (unlikely (query == NULL))
  96         return NULL;
  97
  98     new (&query->xapian_query) Xapian::Query ();
  99     new (&query->terms) std::set<std::string> ();
 100     query->parsed = FALSE;
 101
 102     talloc_set_destructor (query, _notmuch_query_destructor);
 103
 104     query->notmuch = notmuch;
 105
 106     query->query_string = talloc_strdup (query, query_string);
 107
 108     query->sort = NOTMUCH_SORT_NEWEST_FIRST;
 109
 110     query->exclude_terms = _notmuch_string_list_create (query);
 111
 112     query->omit_excluded = NOTMUCH_EXCLUDE_TRUE;
 113
 114     return query;
 115 }
 116
 117 static notmuch_status_t
 118 _notmuch_query_ensure_parsed (notmuch_query_t *query)
 119 {
 120     if (query->parsed)
 121         return NOTMUCH_STATUS_SUCCESS;
 122
 123     try {
 124         query->xapian_query =
 125             query->notmuch->query_parser->
 126                 parse_query (query->query_string, NOTMUCH_QUERY_PARSER_FLAGS);
 127
 128        /* Xapian doesn't support skip_to on terms from a query since
 129         *  they are unordered, so cache a copy of all terms in
 130         *  something searchable.
 131         */
 132
 133         for (Xapian::TermIterator t = query->xapian_query.get_terms_begin ();
 134              t != query->xapian_query.get_terms_end (); ++t)
 135             query->terms.insert (*t);
 136
 137         query->parsed = TRUE;
 138
 139     } catch (const Xapian::Error &error) {
 140         if (!query->notmuch->exception_reported) {
 141             _notmuch_database_log (query->notmuch,
 142                                    "A Xapian exception occurred parsing query: %s\n",
 143                                    error.get_msg ().c_str ());
 144             _notmuch_database_log_append (query->notmuch,
 145                                           "Query string was: %s\n",
 146                                           query->query_string);
 147             query->notmuch->exception_reported = TRUE;
 148         }
 149
 150         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 151     }
 152     return NOTMUCH_STATUS_SUCCESS;
 153 }
 154
 155 const char *
 156 notmuch_query_get_query_string (const notmuch_query_t *query)
 157 {
 158     return query->query_string;
 159 }
 160
 161 void
 162 notmuch_query_set_omit_excluded (notmuch_query_t *query,
 163                                  notmuch_exclude_t omit_excluded)
 164 {
 165     query->omit_excluded = omit_excluded;
 166 }
 167
 168 void
 169 notmuch_query_set_sort (notmuch_query_t *query, notmuch_sort_t sort)
 170 {
 171     query->sort = sort;
 172 }
 173
 174 notmuch_sort_t
 175 notmuch_query_get_sort (const notmuch_query_t *query)
 176 {
 177     return query->sort;
 178 }
 179
 180 void
 181 notmuch_query_add_tag_exclude (notmuch_query_t *query, const char *tag)
 182 {
 183     notmuch_status_t status;
 184     char *term;
 185
 186     status = _notmuch_query_ensure_parsed (query);
 187     /* The following is not ideal error handling, but to avoid
 188      * breaking the ABI, we can live with it for now. In particular at
 189      * least in the notmuch CLI, any syntax error in the query is
 190      * caught in a later call to _notmuch_query_ensure_parsed with a
 191      * better error path.
 192      *
 193      * TODO: add status return to this function.
 194      */
 195     if (status)
 196         return;
 197
 198     term = talloc_asprintf (query, "%s%s", _find_prefix ("tag"), tag);
 199     if (query->terms.count(term) != 0)
 200         return; /* XXX report ignoring exclude? */
 201
 202     _notmuch_string_list_append (query->exclude_terms, term);
 203 }
 204
 205 /* We end up having to call the destructors explicitly because we had
 206  * to use "placement new" in order to initialize C++ objects within a
 207  * block that we allocated with talloc. So C++ is making talloc
 208  * slightly less simple to use, (we wouldn't need
 209  * talloc_set_destructor at all otherwise).
 210  */
 211 static int
 212 _notmuch_messages_destructor (notmuch_mset_messages_t *messages)
 213 {
 214     messages->iterator.~MSetIterator ();
 215     messages->iterator_end.~MSetIterator ();
 216
 217     return 0;
 218 }
 219
 220 /* Return a query that matches messages with the excluded tags
 221  * registered with query. The caller of this function has to combine the returned
 222  * query appropriately.*/
 223 static Xapian::Query
 224 _notmuch_exclude_tags (notmuch_query_t *query)
 225 {
 226     Xapian::Query exclude_query = Xapian::Query::MatchNothing;
 227
 228     for (notmuch_string_node_t *term = query->exclude_terms->head; term;
 229          term = term->next) {
 230         exclude_query = Xapian::Query (Xapian::Query::OP_OR,
 231                                        exclude_query, Xapian::Query (term->string));
 232     }
 233     return exclude_query;
 234 }
 235
 236 notmuch_messages_t *
 237 notmuch_query_search_messages (notmuch_query_t *query)
 238 {
 239     notmuch_status_t status;
 240     notmuch_messages_t *messages;
 241     status = notmuch_query_search_messages_st (query, &messages);
 242     if (status)
 243         return NULL;
 244     else
 245         return messages;
 246 }
 247
 248 notmuch_status_t
 249 notmuch_query_search_messages_st (notmuch_query_t *query,
 250                                   notmuch_messages_t **out)
 251 {
 252     return _notmuch_query_search_documents (query, "mail", out);
 253 }
 254
 255 notmuch_status_t
 256 _notmuch_query_search_documents (notmuch_query_t *query,
 257                                  const char *type,
 258                                  notmuch_messages_t **out)
 259 {
 260     notmuch_database_t *notmuch = query->notmuch;
 261     const char *query_string = query->query_string;
 262     notmuch_mset_messages_t *messages;
 263     notmuch_status_t status;
 264
 265     status = _notmuch_query_ensure_parsed (query);
 266     if (status)
 267         return status;
 268
 269     messages = talloc (query, notmuch_mset_messages_t);
 270     if (unlikely (messages == NULL))
 271         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 272
 273     try {
 274
 275         messages->base.is_of_list_type = FALSE;
 276         messages->base.iterator = NULL;
 277         messages->notmuch = notmuch;
 278         new (&messages->iterator) Xapian::MSetIterator ();
 279         new (&messages->iterator_end) Xapian::MSetIterator ();
 280
 281         talloc_set_destructor (messages, _notmuch_messages_destructor);
 282
 283         Xapian::Enquire enquire (*notmuch->xapian_db);
 284         Xapian::Query mail_query (talloc_asprintf (query, "%s%s",
 285                                                    _find_prefix ("type"),
 286                                                    type));
 287         Xapian::Query final_query, exclude_query;
 288         Xapian::MSet mset;
 289         Xapian::MSetIterator iterator;
 290
 291         if (strcmp (query_string, "") == 0 ||
 292             strcmp (query_string, "*") == 0)
 293         {
 294             final_query = mail_query;
 295         } else {
 296             final_query = Xapian::Query (Xapian::Query::OP_AND,
 297                                          mail_query, query->xapian_query);
 298         }
 299         messages->base.excluded_doc_ids = NULL;
 300
 301         if ((query->omit_excluded != NOTMUCH_EXCLUDE_FALSE) && (query->exclude_terms)) {
 302             exclude_query = _notmuch_exclude_tags (query);
 303
 304             if (query->omit_excluded == NOTMUCH_EXCLUDE_TRUE ||
 305                 query->omit_excluded == NOTMUCH_EXCLUDE_ALL)
 306             {
 307                 final_query = Xapian::Query (Xapian::Query::OP_AND_NOT,
 308                                              final_query, exclude_query);
 309             } else { /* NOTMUCH_EXCLUDE_FLAG */
 310                 exclude_query = Xapian::Query (Xapian::Query::OP_AND,
 311                                            exclude_query, final_query);
 312
 313                 enquire.set_weighting_scheme (Xapian::BoolWeight());
 314                 enquire.set_query (exclude_query);
 315
 316                 mset = enquire.get_mset (0, notmuch->xapian_db->get_doccount ());
 317
 318                 GArray *excluded_doc_ids = g_array_new (FALSE, FALSE, sizeof (unsigned int));
 319
 320                 for (iterator = mset.begin (); iterator != mset.end (); iterator++) {
 321                     unsigned int doc_id = *iterator;
 322                     g_array_append_val (excluded_doc_ids, doc_id);
 323                 }
 324                 messages->base.excluded_doc_ids = talloc (messages, _notmuch_doc_id_set);
 325                 _notmuch_doc_id_set_init (query, messages->base.excluded_doc_ids,
 326                                           excluded_doc_ids);
 327                 g_array_unref (excluded_doc_ids);
 328             }
 329         }
 330
 331
 332         enquire.set_weighting_scheme (Xapian::BoolWeight());
 333
 334         switch (query->sort) {
 335         case NOTMUCH_SORT_OLDEST_FIRST:
 336             enquire.set_sort_by_value (NOTMUCH_VALUE_TIMESTAMP, FALSE);
 337             break;
 338         case NOTMUCH_SORT_NEWEST_FIRST:
 339             enquire.set_sort_by_value (NOTMUCH_VALUE_TIMESTAMP, TRUE);
 340             break;
 341         case NOTMUCH_SORT_MESSAGE_ID:
 342             enquire.set_sort_by_value (NOTMUCH_VALUE_MESSAGE_ID, FALSE);
 343             break;
 344         case NOTMUCH_SORT_UNSORTED:
 345             break;
 346         }
 347
 348         if (_debug_query ()) {
 349             fprintf (stderr, "Exclude query is:\n%s\n",
 350                      exclude_query.get_description ().c_str ());
 351             fprintf (stderr, "Final query is:\n%s\n",
 352                      final_query.get_description ().c_str ());
 353         }
 354
 355         enquire.set_query (final_query);
 356
 357         mset = enquire.get_mset (0, notmuch->xapian_db->get_doccount ());
 358
 359         messages->iterator = mset.begin ();
 360         messages->iterator_end = mset.end ();
 361
 362         *out = &messages->base;
 363         return NOTMUCH_STATUS_SUCCESS;
 364
 365     } catch (const Xapian::Error &error) {
 366         _notmuch_database_log (notmuch,
 367                                "A Xapian exception occurred performing query: %s\n",
 368                                error.get_msg().c_str());
 369         _notmuch_database_log_append (notmuch,
 370                                "Query string was: %s\n",
 371                                query->query_string);
 372
 373         notmuch->exception_reported = TRUE;
 374         talloc_free (messages);
 375         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 376     }
 377 }
 378
 379 notmuch_bool_t
 380 _notmuch_mset_messages_valid (notmuch_messages_t *messages)
 381 {
 382     notmuch_mset_messages_t *mset_messages;
 383
 384     mset_messages = (notmuch_mset_messages_t *) messages;
 385
 386     return (mset_messages->iterator != mset_messages->iterator_end);
 387 }
 388
 389 static Xapian::docid
 390 _notmuch_mset_messages_get_doc_id (notmuch_messages_t *messages)
 391 {
 392     notmuch_mset_messages_t *mset_messages;
 393
 394     mset_messages = (notmuch_mset_messages_t *) messages;
 395
 396     if (! _notmuch_mset_messages_valid (&mset_messages->base))
 397         return 0;
 398
 399     return *mset_messages->iterator;
 400 }
 401
 402 notmuch_message_t *
 403 _notmuch_mset_messages_get (notmuch_messages_t *messages)
 404 {
 405     notmuch_message_t *message;
 406     Xapian::docid doc_id;
 407     notmuch_private_status_t status;
 408     notmuch_mset_messages_t *mset_messages;
 409
 410     mset_messages = (notmuch_mset_messages_t *) messages;
 411
 412     if (! _notmuch_mset_messages_valid (&mset_messages->base))
 413         return NULL;
 414
 415     doc_id = *mset_messages->iterator;
 416
 417     message = _notmuch_message_create (mset_messages,
 418                                        mset_messages->notmuch, doc_id,
 419                                        &status);
 420
 421     if (message == NULL &&
 422        status == NOTMUCH_PRIVATE_STATUS_NO_DOCUMENT_FOUND)
 423     {
 424         INTERNAL_ERROR ("a messages iterator contains a non-existent document ID.\n");
 425     }
 426
 427     if (messages->excluded_doc_ids &&
 428         _notmuch_doc_id_set_contains (messages->excluded_doc_ids, doc_id))
 429         notmuch_message_set_flag (message, NOTMUCH_MESSAGE_FLAG_EXCLUDED, TRUE);
 430
 431     return message;
 432 }
 433
 434 void
 435 _notmuch_mset_messages_move_to_next (notmuch_messages_t *messages)
 436 {
 437     notmuch_mset_messages_t *mset_messages;
 438
 439     mset_messages = (notmuch_mset_messages_t *) messages;
 440
 441     mset_messages->iterator++;
 442 }
 443
 444 static notmuch_bool_t
 445 _notmuch_doc_id_set_init (void *ctx,
 446                           notmuch_doc_id_set_t *doc_ids,
 447                           GArray *arr)
 448 {
 449     unsigned int max = 0;
 450     unsigned char *bitmap;
 451
 452     for (unsigned int i = 0; i < arr->len; i++)
 453         max = MAX(max, g_array_index (arr, unsigned int, i));
 454     bitmap = talloc_zero_array (ctx, unsigned char, DOCIDSET_WORD(max) + 1);
 455
 456     if (bitmap == NULL)
 457         return FALSE;
 458
 459     doc_ids->bitmap = bitmap;
 460     doc_ids->bound = max + 1;
 461
 462     for (unsigned int i = 0; i < arr->len; i++) {
 463         unsigned int doc_id = g_array_index (arr, unsigned int, i);
 464         bitmap[DOCIDSET_WORD(doc_id)] |= 1 << DOCIDSET_BIT(doc_id);
 465     }
 466
 467     return TRUE;
 468 }
 469
 470 notmuch_bool_t
 471 _notmuch_doc_id_set_contains (notmuch_doc_id_set_t *doc_ids,
 472                               unsigned int doc_id)
 473 {
 474     if (doc_id >= doc_ids->bound)
 475         return FALSE;
 476     return doc_ids->bitmap[DOCIDSET_WORD(doc_id)] & (1 << DOCIDSET_BIT(doc_id));
 477 }
 478
 479 void
 480 _notmuch_doc_id_set_remove (notmuch_doc_id_set_t *doc_ids,
 481                             unsigned int doc_id)
 482 {
 483     if (doc_id < doc_ids->bound)
 484         doc_ids->bitmap[DOCIDSET_WORD(doc_id)] &= ~(1 << DOCIDSET_BIT(doc_id));
 485 }
 486
 487 /* Glib objects force use to use a talloc destructor as well, (but not
 488  * nearly as ugly as the for messages due to C++ objects). At
 489  * this point, I'd really like to have some talloc-friendly
 490  * equivalents for the few pieces of glib that I'm using. */
 491 static int
 492 _notmuch_threads_destructor (notmuch_threads_t *threads)
 493 {
 494     if (threads->doc_ids)
 495         g_array_unref (threads->doc_ids);
 496
 497     return 0;
 498 }
 499
 500 notmuch_status_t
 501 notmuch_query_search_threads_st (notmuch_query_t *query, notmuch_threads_t **out)
 502 {
 503     return notmuch_query_search_threads(query, out);
 504 }
 505
 506 notmuch_status_t
 507 notmuch_query_search_threads (notmuch_query_t *query,
 508                               notmuch_threads_t **out)
 509 {
 510     notmuch_threads_t *threads;
 511     notmuch_messages_t *messages;
 512     notmuch_status_t status;
 513
 514     threads = talloc (query, notmuch_threads_t);
 515     if (threads == NULL)
 516         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 517     threads->doc_ids = NULL;
 518     talloc_set_destructor (threads, _notmuch_threads_destructor);
 519
 520     threads->query = query;
 521
 522     status = notmuch_query_search_messages_st (query, &messages);
 523     if (status) {
 524         talloc_free (threads);
 525         return status;
 526     }
 527
 528     threads->doc_ids = g_array_new (FALSE, FALSE, sizeof (unsigned int));
 529     while (notmuch_messages_valid (messages)) {
 530         unsigned int doc_id = _notmuch_mset_messages_get_doc_id (messages);
 531         g_array_append_val (threads->doc_ids, doc_id);
 532         notmuch_messages_move_to_next (messages);
 533     }
 534     threads->doc_id_pos = 0;
 535
 536     talloc_free (messages);
 537
 538     if (! _notmuch_doc_id_set_init (threads, &threads->match_set,
 539                                     threads->doc_ids)) {
 540         talloc_free (threads);
 541         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 542     }
 543
 544     *out = threads;
 545     return NOTMUCH_STATUS_SUCCESS;
 546 }
 547
 548 void
 549 notmuch_query_destroy (notmuch_query_t *query)
 550 {
 551     talloc_free (query);
 552 }
 553
 554 notmuch_bool_t
 555 notmuch_threads_valid (notmuch_threads_t *threads)
 556 {
 557     unsigned int doc_id;
 558
 559     if (! threads)
 560         return FALSE;
 561
 562     while (threads->doc_id_pos < threads->doc_ids->len) {
 563         doc_id = g_array_index (threads->doc_ids, unsigned int,
 564                                 threads->doc_id_pos);
 565         if (_notmuch_doc_id_set_contains (&threads->match_set, doc_id))
 566             break;
 567
 568         threads->doc_id_pos++;
 569     }
 570
 571     return threads->doc_id_pos < threads->doc_ids->len;
 572 }
 573
 574 notmuch_thread_t *
 575 notmuch_threads_get (notmuch_threads_t *threads)
 576 {
 577     unsigned int doc_id;
 578
 579     if (! notmuch_threads_valid (threads))
 580         return NULL;
 581
 582     doc_id = g_array_index (threads->doc_ids, unsigned int,
 583                             threads->doc_id_pos);
 584     return _notmuch_thread_create (threads->query,
 585                                    threads->query->notmuch,
 586                                    doc_id,
 587                                    &threads->match_set,
 588                                    threads->query->exclude_terms,
 589                                    threads->query->omit_excluded,
 590                                    threads->query->sort);
 591 }
 592
 593 void
 594 notmuch_threads_move_to_next (notmuch_threads_t *threads)
 595 {
 596     threads->doc_id_pos++;
 597 }
 598
 599 void
 600 notmuch_threads_destroy (notmuch_threads_t *threads)
 601 {
 602     talloc_free (threads);
 603 }
 604
 605 unsigned int
 606 notmuch_query_count_messages (notmuch_query_t *query)
 607 {
 608     notmuch_status_t status;
 609     unsigned int count;
 610
 611     status = notmuch_query_count_messages_st (query, &count);
 612     return status ? 0 : count;
 613 }
 614
 615 notmuch_status_t
 616 notmuch_query_count_messages_st (notmuch_query_t *query, unsigned *count_out)
 617 {
 618     return _notmuch_query_count_documents (query, "mail", count_out);
 619 }
 620
 621 notmuch_status_t
 622 _notmuch_query_count_documents (notmuch_query_t *query, const char *type, unsigned *count_out)
 623 {
 624     notmuch_database_t *notmuch = query->notmuch;
 625     const char *query_string = query->query_string;
 626     Xapian::doccount count = 0;
 627     notmuch_status_t status;
 628
 629     status = _notmuch_query_ensure_parsed (query);
 630     if (status)
 631         return status;
 632
 633     try {
 634         Xapian::Enquire enquire (*notmuch->xapian_db);
 635         Xapian::Query mail_query (talloc_asprintf (query, "%s%s",
 636                                                    _find_prefix ("type"),
 637                                                    type));
 638         Xapian::Query final_query, exclude_query;
 639         Xapian::MSet mset;
 640
 641         if (strcmp (query_string, "") == 0 ||
 642             strcmp (query_string, "*") == 0)
 643         {
 644             final_query = mail_query;
 645         } else {
 646             final_query = Xapian::Query (Xapian::Query::OP_AND,
 647                                          mail_query, query->xapian_query);
 648         }
 649
 650         exclude_query = _notmuch_exclude_tags (query);
 651
 652         final_query = Xapian::Query (Xapian::Query::OP_AND_NOT,
 653                                          final_query, exclude_query);
 654
 655         enquire.set_weighting_scheme(Xapian::BoolWeight());
 656         enquire.set_docid_order(Xapian::Enquire::ASCENDING);
 657
 658         if (_debug_query ()) {
 659             fprintf (stderr, "Exclude query is:\n%s\n",
 660                      exclude_query.get_description ().c_str ());
 661             fprintf (stderr, "Final query is:\n%s\n",
 662                      final_query.get_description ().c_str ());
 663         }
 664
 665         enquire.set_query (final_query);
 666
 667         /*
 668          * Set the checkatleast parameter to the number of documents
 669          * in the database to make get_matches_estimated() exact.
 670          * Set the max parameter to 0 to avoid fetching documents we will discard.
 671          */
 672         mset = enquire.get_mset (0, 0,
 673                                  notmuch->xapian_db->get_doccount ());
 674
 675         count = mset.get_matches_estimated();
 676
 677     } catch (const Xapian::Error &error) {
 678         _notmuch_database_log (notmuch,
 679                                "A Xapian exception occurred performing query: %s\n",
 680                                error.get_msg().c_str());
 681         _notmuch_database_log_append (notmuch,
 682                                       "Query string was: %s\n",
 683                                       query->query_string);
 684         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 685     }
 686
 687     *count_out = count;
 688     return NOTMUCH_STATUS_SUCCESS;
 689 }
 690
 691 unsigned
 692 notmuch_query_count_threads (notmuch_query_t *query)
 693 {
 694     notmuch_status_t status;
 695     unsigned int count;
 696
 697     status = notmuch_query_count_threads_st (query, &count);
 698     return status ? 0 : count;
 699 }
 700
 701 notmuch_status_t
 702 notmuch_query_count_threads_st (notmuch_query_t *query, unsigned *count)
 703 {
 704     notmuch_messages_t *messages;
 705     GHashTable *hash;
 706     notmuch_sort_t sort;
 707     notmuch_status_t ret = NOTMUCH_STATUS_SUCCESS;
 708
 709     sort = query->sort;
 710     query->sort = NOTMUCH_SORT_UNSORTED;
 711     ret = notmuch_query_search_messages_st (query, &messages);
 712     if (ret)
 713         return ret;
 714     query->sort = sort;
 715     if (messages == NULL)
 716         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 717
 718     hash = g_hash_table_new_full (g_str_hash, g_str_equal, NULL, NULL);
 719     if (hash == NULL) {
 720         talloc_free (messages);
 721         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 722     }
 723
 724     while (notmuch_messages_valid (messages)) {
 725         notmuch_message_t *message = notmuch_messages_get (messages);
 726         const char *thread_id = notmuch_message_get_thread_id (message);
 727         char *thread_id_copy = talloc_strdup (messages, thread_id);
 728         if (unlikely (thread_id_copy == NULL)) {
 729             notmuch_message_destroy (message);
 730             ret = NOTMUCH_STATUS_OUT_OF_MEMORY;
 731             goto DONE;
 732         }
 733         g_hash_table_insert (hash, thread_id_copy, NULL);
 734         notmuch_message_destroy (message);
 735         notmuch_messages_move_to_next (messages);
 736     }
 737
 738     *count = g_hash_table_size (hash);
 739
 740   DONE:
 741     g_hash_table_unref (hash);
 742     talloc_free (messages);
 743
 744     return ret;
 745 }
 746
 747 notmuch_database_t *
 748 notmuch_query_get_database (const notmuch_query_t *query)
 749 {
 750     return query->notmuch;
 751 }