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