git.notmuchmail.org Git - notmuch/blob - lib/query.cc

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