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 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 };
  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
 224         if (strcmp (query_string, "") == 0 ||
 225             strcmp (query_string, "*") == 0)
 226         {
 227             final_query = mail_query;
 228         } else {
 229             string_query = notmuch->query_parser->
 230                 parse_query (query_string, NOTMUCH_QUERY_PARSER_FLAGS);
 231             final_query = Xapian::Query (Xapian::Query::OP_AND,
 232                                          mail_query, string_query);
 233         }
 234         messages->base.excluded_doc_ids = NULL;
 235
 236         if ((query->omit_excluded != NOTMUCH_EXCLUDE_FALSE) && (query->exclude_terms)) {
 237             exclude_query = _notmuch_exclude_tags (query, final_query);
 238
 239             if (query->omit_excluded == NOTMUCH_EXCLUDE_TRUE ||
 240                 query->omit_excluded == NOTMUCH_EXCLUDE_ALL)
 241             {
 242                 final_query = Xapian::Query (Xapian::Query::OP_AND_NOT,
 243                                              final_query, exclude_query);
 244             } else { /* NOTMUCH_EXCLUDE_FLAG */
 245                 exclude_query = Xapian::Query (Xapian::Query::OP_AND,
 246                                            exclude_query, final_query);
 247
 248                 enquire.set_weighting_scheme (Xapian::BoolWeight());
 249                 enquire.set_query (exclude_query);
 250
 251                 mset = enquire.get_mset (0, notmuch->xapian_db->get_doccount ());
 252
 253                 GArray *excluded_doc_ids = g_array_new (FALSE, FALSE, sizeof (unsigned int));
 254
 255                 for (iterator = mset.begin (); iterator != mset.end (); iterator++) {
 256                     unsigned int doc_id = *iterator;
 257                     g_array_append_val (excluded_doc_ids, doc_id);
 258                 }
 259                 messages->base.excluded_doc_ids = talloc (messages, _notmuch_doc_id_set);
 260                 _notmuch_doc_id_set_init (query, messages->base.excluded_doc_ids,
 261                                           excluded_doc_ids);
 262                 g_array_unref (excluded_doc_ids);
 263             }
 264         }
 265
 266
 267         enquire.set_weighting_scheme (Xapian::BoolWeight());
 268
 269         switch (query->sort) {
 270         case NOTMUCH_SORT_OLDEST_FIRST:
 271             enquire.set_sort_by_value (NOTMUCH_VALUE_TIMESTAMP, FALSE);
 272             break;
 273         case NOTMUCH_SORT_NEWEST_FIRST:
 274             enquire.set_sort_by_value (NOTMUCH_VALUE_TIMESTAMP, TRUE);
 275             break;
 276         case NOTMUCH_SORT_MESSAGE_ID:
 277             enquire.set_sort_by_value (NOTMUCH_VALUE_MESSAGE_ID, FALSE);
 278             break;
 279         case NOTMUCH_SORT_UNSORTED:
 280             break;
 281         }
 282
 283         if (_debug_query ()) {
 284             fprintf (stderr, "Exclude query is:\n%s\n",
 285                      exclude_query.get_description ().c_str ());
 286             fprintf (stderr, "Final query is:\n%s\n",
 287                      final_query.get_description ().c_str ());
 288         }
 289
 290         enquire.set_query (final_query);
 291
 292         mset = enquire.get_mset (0, notmuch->xapian_db->get_doccount ());
 293
 294         messages->iterator = mset.begin ();
 295         messages->iterator_end = mset.end ();
 296
 297         *out = &messages->base;
 298         return NOTMUCH_STATUS_SUCCESS;
 299
 300     } catch (const Xapian::Error &error) {
 301         _notmuch_database_log (notmuch,
 302                                "A Xapian exception occurred performing query: %s\n",
 303                                error.get_msg().c_str());
 304         _notmuch_database_log_append (notmuch,
 305                                "Query string was: %s\n",
 306                                query->query_string);
 307
 308         notmuch->exception_reported = TRUE;
 309         talloc_free (messages);
 310         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 311     }
 312 }
 313
 314 notmuch_bool_t
 315 _notmuch_mset_messages_valid (notmuch_messages_t *messages)
 316 {
 317     notmuch_mset_messages_t *mset_messages;
 318
 319     mset_messages = (notmuch_mset_messages_t *) messages;
 320
 321     return (mset_messages->iterator != mset_messages->iterator_end);
 322 }
 323
 324 static Xapian::docid
 325 _notmuch_mset_messages_get_doc_id (notmuch_messages_t *messages)
 326 {
 327     notmuch_mset_messages_t *mset_messages;
 328
 329     mset_messages = (notmuch_mset_messages_t *) messages;
 330
 331     if (! _notmuch_mset_messages_valid (&mset_messages->base))
 332         return 0;
 333
 334     return *mset_messages->iterator;
 335 }
 336
 337 notmuch_message_t *
 338 _notmuch_mset_messages_get (notmuch_messages_t *messages)
 339 {
 340     notmuch_message_t *message;
 341     Xapian::docid doc_id;
 342     notmuch_private_status_t status;
 343     notmuch_mset_messages_t *mset_messages;
 344
 345     mset_messages = (notmuch_mset_messages_t *) messages;
 346
 347     if (! _notmuch_mset_messages_valid (&mset_messages->base))
 348         return NULL;
 349
 350     doc_id = *mset_messages->iterator;
 351
 352     message = _notmuch_message_create (mset_messages,
 353                                        mset_messages->notmuch, doc_id,
 354                                        &status);
 355
 356     if (message == NULL &&
 357        status == NOTMUCH_PRIVATE_STATUS_NO_DOCUMENT_FOUND)
 358     {
 359         INTERNAL_ERROR ("a messages iterator contains a non-existent document ID.\n");
 360     }
 361
 362     if (messages->excluded_doc_ids &&
 363         _notmuch_doc_id_set_contains (messages->excluded_doc_ids, doc_id))
 364         notmuch_message_set_flag (message, NOTMUCH_MESSAGE_FLAG_EXCLUDED, TRUE);
 365
 366     return message;
 367 }
 368
 369 void
 370 _notmuch_mset_messages_move_to_next (notmuch_messages_t *messages)
 371 {
 372     notmuch_mset_messages_t *mset_messages;
 373
 374     mset_messages = (notmuch_mset_messages_t *) messages;
 375
 376     mset_messages->iterator++;
 377 }
 378
 379 static notmuch_bool_t
 380 _notmuch_doc_id_set_init (void *ctx,
 381                           notmuch_doc_id_set_t *doc_ids,
 382                           GArray *arr)
 383 {
 384     unsigned int max = 0;
 385     unsigned char *bitmap;
 386
 387     for (unsigned int i = 0; i < arr->len; i++)
 388         max = MAX(max, g_array_index (arr, unsigned int, i));
 389     bitmap = talloc_zero_array (ctx, unsigned char, DOCIDSET_WORD(max) + 1);
 390
 391     if (bitmap == NULL)
 392         return FALSE;
 393
 394     doc_ids->bitmap = bitmap;
 395     doc_ids->bound = max + 1;
 396
 397     for (unsigned int i = 0; i < arr->len; i++) {
 398         unsigned int doc_id = g_array_index (arr, unsigned int, i);
 399         bitmap[DOCIDSET_WORD(doc_id)] |= 1 << DOCIDSET_BIT(doc_id);
 400     }
 401
 402     return TRUE;
 403 }
 404
 405 notmuch_bool_t
 406 _notmuch_doc_id_set_contains (notmuch_doc_id_set_t *doc_ids,
 407                               unsigned int doc_id)
 408 {
 409     if (doc_id >= doc_ids->bound)
 410         return FALSE;
 411     return doc_ids->bitmap[DOCIDSET_WORD(doc_id)] & (1 << DOCIDSET_BIT(doc_id));
 412 }
 413
 414 void
 415 _notmuch_doc_id_set_remove (notmuch_doc_id_set_t *doc_ids,
 416                             unsigned int doc_id)
 417 {
 418     if (doc_id < doc_ids->bound)
 419         doc_ids->bitmap[DOCIDSET_WORD(doc_id)] &= ~(1 << DOCIDSET_BIT(doc_id));
 420 }
 421
 422 /* Glib objects force use to use a talloc destructor as well, (but not
 423  * nearly as ugly as the for messages due to C++ objects). At
 424  * this point, I'd really like to have some talloc-friendly
 425  * equivalents for the few pieces of glib that I'm using. */
 426 static int
 427 _notmuch_threads_destructor (notmuch_threads_t *threads)
 428 {
 429     if (threads->doc_ids)
 430         g_array_unref (threads->doc_ids);
 431
 432     return 0;
 433 }
 434
 435
 436 notmuch_threads_t *
 437 notmuch_query_search_threads (notmuch_query_t *query)
 438 {
 439     notmuch_status_t status;
 440     notmuch_threads_t *threads;
 441     status = notmuch_query_search_threads_st (query, &threads);
 442     if (status)
 443         return NULL;
 444     else
 445         return threads;
 446 }
 447
 448 notmuch_status_t
 449 notmuch_query_search_threads_st (notmuch_query_t *query,
 450                                  notmuch_threads_t **out)
 451 {
 452     notmuch_threads_t *threads;
 453     notmuch_messages_t *messages;
 454     notmuch_status_t status;
 455
 456     threads = talloc (query, notmuch_threads_t);
 457     if (threads == NULL)
 458         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 459     threads->doc_ids = NULL;
 460     talloc_set_destructor (threads, _notmuch_threads_destructor);
 461
 462     threads->query = query;
 463
 464     status = notmuch_query_search_messages_st (query, &messages);
 465     if (status) {
 466         talloc_free (threads);
 467         return status;
 468     }
 469
 470     threads->doc_ids = g_array_new (FALSE, FALSE, sizeof (unsigned int));
 471     while (notmuch_messages_valid (messages)) {
 472         unsigned int doc_id = _notmuch_mset_messages_get_doc_id (messages);
 473         g_array_append_val (threads->doc_ids, doc_id);
 474         notmuch_messages_move_to_next (messages);
 475     }
 476     threads->doc_id_pos = 0;
 477
 478     talloc_free (messages);
 479
 480     if (! _notmuch_doc_id_set_init (threads, &threads->match_set,
 481                                     threads->doc_ids)) {
 482         talloc_free (threads);
 483         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 484     }
 485
 486     *out = threads;
 487     return NOTMUCH_STATUS_SUCCESS;
 488 }
 489
 490 void
 491 notmuch_query_destroy (notmuch_query_t *query)
 492 {
 493     talloc_free (query);
 494 }
 495
 496 notmuch_bool_t
 497 notmuch_threads_valid (notmuch_threads_t *threads)
 498 {
 499     unsigned int doc_id;
 500
 501     if (! threads)
 502         return FALSE;
 503
 504     while (threads->doc_id_pos < threads->doc_ids->len) {
 505         doc_id = g_array_index (threads->doc_ids, unsigned int,
 506                                 threads->doc_id_pos);
 507         if (_notmuch_doc_id_set_contains (&threads->match_set, doc_id))
 508             break;
 509
 510         threads->doc_id_pos++;
 511     }
 512
 513     return threads->doc_id_pos < threads->doc_ids->len;
 514 }
 515
 516 notmuch_thread_t *
 517 notmuch_threads_get (notmuch_threads_t *threads)
 518 {
 519     unsigned int doc_id;
 520
 521     if (! notmuch_threads_valid (threads))
 522         return NULL;
 523
 524     doc_id = g_array_index (threads->doc_ids, unsigned int,
 525                             threads->doc_id_pos);
 526     return _notmuch_thread_create (threads->query,
 527                                    threads->query->notmuch,
 528                                    doc_id,
 529                                    &threads->match_set,
 530                                    threads->query->exclude_terms,
 531                                    threads->query->omit_excluded,
 532                                    threads->query->sort);
 533 }
 534
 535 void
 536 notmuch_threads_move_to_next (notmuch_threads_t *threads)
 537 {
 538     threads->doc_id_pos++;
 539 }
 540
 541 void
 542 notmuch_threads_destroy (notmuch_threads_t *threads)
 543 {
 544     talloc_free (threads);
 545 }
 546
 547 unsigned int
 548 notmuch_query_count_messages (notmuch_query_t *query)
 549 {
 550     notmuch_status_t status;
 551     unsigned int count;
 552
 553     status = notmuch_query_count_messages_st (query, &count);
 554     return status ? 0 : count;
 555 }
 556
 557 notmuch_status_t
 558 notmuch_query_count_messages_st (notmuch_query_t *query, unsigned *count_out)
 559 {
 560     return _notmuch_query_count_documents (query, "mail", count_out);
 561 }
 562
 563 notmuch_status_t
 564 _notmuch_query_count_documents (notmuch_query_t *query, const char *type, unsigned *count_out)
 565 {
 566     notmuch_database_t *notmuch = query->notmuch;
 567     const char *query_string = query->query_string;
 568     Xapian::doccount count = 0;
 569
 570     try {
 571         Xapian::Enquire enquire (*notmuch->xapian_db);
 572         Xapian::Query mail_query (talloc_asprintf (query, "%s%s",
 573                                                    _find_prefix ("type"),
 574                                                    type));
 575         Xapian::Query string_query, final_query, exclude_query;
 576         Xapian::MSet mset;
 577
 578         if (strcmp (query_string, "") == 0 ||
 579             strcmp (query_string, "*") == 0)
 580         {
 581             final_query = mail_query;
 582         } else {
 583             string_query = notmuch->query_parser->
 584                 parse_query (query_string, NOTMUCH_QUERY_PARSER_FLAGS);
 585             final_query = Xapian::Query (Xapian::Query::OP_AND,
 586                                          mail_query, string_query);
 587         }
 588
 589         exclude_query = _notmuch_exclude_tags (query, final_query);
 590
 591         final_query = Xapian::Query (Xapian::Query::OP_AND_NOT,
 592                                          final_query, exclude_query);
 593
 594         enquire.set_weighting_scheme(Xapian::BoolWeight());
 595         enquire.set_docid_order(Xapian::Enquire::ASCENDING);
 596
 597         if (_debug_query ()) {
 598             fprintf (stderr, "Exclude query is:\n%s\n",
 599                      exclude_query.get_description ().c_str ());
 600             fprintf (stderr, "Final query is:\n%s\n",
 601                      final_query.get_description ().c_str ());
 602         }
 603
 604         enquire.set_query (final_query);
 605
 606         /*
 607          * Set the checkatleast parameter to the number of documents
 608          * in the database to make get_matches_estimated() exact.
 609          * Set the max parameter to 0 to avoid fetching documents we will discard.
 610          */
 611         mset = enquire.get_mset (0, 0,
 612                                  notmuch->xapian_db->get_doccount ());
 613
 614         count = mset.get_matches_estimated();
 615
 616     } catch (const Xapian::Error &error) {
 617         _notmuch_database_log (notmuch,
 618                                "A Xapian exception occurred performing query: %s\n",
 619                                error.get_msg().c_str());
 620         _notmuch_database_log_append (notmuch,
 621                                       "Query string was: %s\n",
 622                                       query->query_string);
 623         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 624     }
 625
 626     *count_out = count;
 627     return NOTMUCH_STATUS_SUCCESS;
 628 }
 629
 630 unsigned
 631 notmuch_query_count_threads (notmuch_query_t *query)
 632 {
 633     notmuch_status_t status;
 634     unsigned int count;
 635
 636     status = notmuch_query_count_threads_st (query, &count);
 637     return status ? 0 : count;
 638 }
 639
 640 notmuch_status_t
 641 notmuch_query_count_threads_st (notmuch_query_t *query, unsigned *count)
 642 {
 643     notmuch_messages_t *messages;
 644     GHashTable *hash;
 645     notmuch_sort_t sort;
 646     notmuch_status_t ret = NOTMUCH_STATUS_SUCCESS;
 647
 648     sort = query->sort;
 649     query->sort = NOTMUCH_SORT_UNSORTED;
 650     ret = notmuch_query_search_messages_st (query, &messages);
 651     if (ret)
 652         return ret;
 653     query->sort = sort;
 654     if (messages == NULL)
 655         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 656
 657     hash = g_hash_table_new_full (g_str_hash, g_str_equal, NULL, NULL);
 658     if (hash == NULL) {
 659         talloc_free (messages);
 660         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 661     }
 662
 663     while (notmuch_messages_valid (messages)) {
 664         notmuch_message_t *message = notmuch_messages_get (messages);
 665         const char *thread_id = notmuch_message_get_thread_id (message);
 666         char *thread_id_copy = talloc_strdup (messages, thread_id);
 667         if (unlikely (thread_id_copy == NULL)) {
 668             notmuch_message_destroy (message);
 669             ret = NOTMUCH_STATUS_OUT_OF_MEMORY;
 670             goto DONE;
 671         }
 672         g_hash_table_insert (hash, thread_id_copy, NULL);
 673         notmuch_message_destroy (message);
 674         notmuch_messages_move_to_next (messages);
 675     }
 676
 677     *count = g_hash_table_size (hash);
 678
 679   DONE:
 680     g_hash_table_unref (hash);
 681     talloc_free (messages);
 682
 683     return ret;
 684 }
 685
 686 notmuch_database_t *
 687 notmuch_query_get_database (const notmuch_query_t *query)
 688 {
 689     return query->notmuch;
 690 }