git.cworth.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     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
 501 notmuch_threads_t *
 502 notmuch_query_search_threads (notmuch_query_t *query)
 503 {
 504     notmuch_status_t status;
 505     notmuch_threads_t *threads;
 506     status = notmuch_query_search_threads_st (query, &threads);
 507     if (status)
 508         return NULL;
 509     else
 510         return threads;
 511 }
 512
 513 notmuch_status_t
 514 notmuch_query_search_threads_st (notmuch_query_t *query,
 515                                  notmuch_threads_t **out)
 516 {
 517     notmuch_threads_t *threads;
 518     notmuch_messages_t *messages;
 519     notmuch_status_t status;
 520
 521     threads = talloc (query, notmuch_threads_t);
 522     if (threads == NULL)
 523         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 524     threads->doc_ids = NULL;
 525     talloc_set_destructor (threads, _notmuch_threads_destructor);
 526
 527     threads->query = query;
 528
 529     status = notmuch_query_search_messages_st (query, &messages);
 530     if (status) {
 531         talloc_free (threads);
 532         return status;
 533     }
 534
 535     threads->doc_ids = g_array_new (FALSE, FALSE, sizeof (unsigned int));
 536     while (notmuch_messages_valid (messages)) {
 537         unsigned int doc_id = _notmuch_mset_messages_get_doc_id (messages);
 538         g_array_append_val (threads->doc_ids, doc_id);
 539         notmuch_messages_move_to_next (messages);
 540     }
 541     threads->doc_id_pos = 0;
 542
 543     talloc_free (messages);
 544
 545     if (! _notmuch_doc_id_set_init (threads, &threads->match_set,
 546                                     threads->doc_ids)) {
 547         talloc_free (threads);
 548         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 549     }
 550
 551     *out = threads;
 552     return NOTMUCH_STATUS_SUCCESS;
 553 }
 554
 555 void
 556 notmuch_query_destroy (notmuch_query_t *query)
 557 {
 558     talloc_free (query);
 559 }
 560
 561 notmuch_bool_t
 562 notmuch_threads_valid (notmuch_threads_t *threads)
 563 {
 564     unsigned int doc_id;
 565
 566     if (! threads)
 567         return FALSE;
 568
 569     while (threads->doc_id_pos < threads->doc_ids->len) {
 570         doc_id = g_array_index (threads->doc_ids, unsigned int,
 571                                 threads->doc_id_pos);
 572         if (_notmuch_doc_id_set_contains (&threads->match_set, doc_id))
 573             break;
 574
 575         threads->doc_id_pos++;
 576     }
 577
 578     return threads->doc_id_pos < threads->doc_ids->len;
 579 }
 580
 581 notmuch_thread_t *
 582 notmuch_threads_get (notmuch_threads_t *threads)
 583 {
 584     unsigned int doc_id;
 585
 586     if (! notmuch_threads_valid (threads))
 587         return NULL;
 588
 589     doc_id = g_array_index (threads->doc_ids, unsigned int,
 590                             threads->doc_id_pos);
 591     return _notmuch_thread_create (threads->query,
 592                                    threads->query->notmuch,
 593                                    doc_id,
 594                                    &threads->match_set,
 595                                    threads->query->exclude_terms,
 596                                    threads->query->omit_excluded,
 597                                    threads->query->sort);
 598 }
 599
 600 void
 601 notmuch_threads_move_to_next (notmuch_threads_t *threads)
 602 {
 603     threads->doc_id_pos++;
 604 }
 605
 606 void
 607 notmuch_threads_destroy (notmuch_threads_t *threads)
 608 {
 609     talloc_free (threads);
 610 }
 611
 612 unsigned int
 613 notmuch_query_count_messages (notmuch_query_t *query)
 614 {
 615     notmuch_status_t status;
 616     unsigned int count;
 617
 618     status = notmuch_query_count_messages_st (query, &count);
 619     return status ? 0 : count;
 620 }
 621
 622 notmuch_status_t
 623 notmuch_query_count_messages_st (notmuch_query_t *query, unsigned *count_out)
 624 {
 625     return _notmuch_query_count_documents (query, "mail", count_out);
 626 }
 627
 628 notmuch_status_t
 629 _notmuch_query_count_documents (notmuch_query_t *query, const char *type, unsigned *count_out)
 630 {
 631     notmuch_database_t *notmuch = query->notmuch;
 632     const char *query_string = query->query_string;
 633     Xapian::doccount count = 0;
 634     notmuch_status_t status;
 635
 636     status = _notmuch_query_ensure_parsed (query);
 637     if (status)
 638         return status;
 639
 640     try {
 641         Xapian::Enquire enquire (*notmuch->xapian_db);
 642         Xapian::Query mail_query (talloc_asprintf (query, "%s%s",
 643                                                    _find_prefix ("type"),
 644                                                    type));
 645         Xapian::Query final_query, exclude_query;
 646         Xapian::MSet mset;
 647
 648         if (strcmp (query_string, "") == 0 ||
 649             strcmp (query_string, "*") == 0)
 650         {
 651             final_query = mail_query;
 652         } else {
 653             final_query = Xapian::Query (Xapian::Query::OP_AND,
 654                                          mail_query, query->xapian_query);
 655         }
 656
 657         exclude_query = _notmuch_exclude_tags (query);
 658
 659         final_query = Xapian::Query (Xapian::Query::OP_AND_NOT,
 660                                          final_query, exclude_query);
 661
 662         enquire.set_weighting_scheme(Xapian::BoolWeight());
 663         enquire.set_docid_order(Xapian::Enquire::ASCENDING);
 664
 665         if (_debug_query ()) {
 666             fprintf (stderr, "Exclude query is:\n%s\n",
 667                      exclude_query.get_description ().c_str ());
 668             fprintf (stderr, "Final query is:\n%s\n",
 669                      final_query.get_description ().c_str ());
 670         }
 671
 672         enquire.set_query (final_query);
 673
 674         /*
 675          * Set the checkatleast parameter to the number of documents
 676          * in the database to make get_matches_estimated() exact.
 677          * Set the max parameter to 0 to avoid fetching documents we will discard.
 678          */
 679         mset = enquire.get_mset (0, 0,
 680                                  notmuch->xapian_db->get_doccount ());
 681
 682         count = mset.get_matches_estimated();
 683
 684     } catch (const Xapian::Error &error) {
 685         _notmuch_database_log (notmuch,
 686                                "A Xapian exception occurred performing query: %s\n",
 687                                error.get_msg().c_str());
 688         _notmuch_database_log_append (notmuch,
 689                                       "Query string was: %s\n",
 690                                       query->query_string);
 691         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 692     }
 693
 694     *count_out = count;
 695     return NOTMUCH_STATUS_SUCCESS;
 696 }
 697
 698 unsigned
 699 notmuch_query_count_threads (notmuch_query_t *query)
 700 {
 701     notmuch_status_t status;
 702     unsigned int count;
 703
 704     status = notmuch_query_count_threads_st (query, &count);
 705     return status ? 0 : count;
 706 }
 707
 708 notmuch_status_t
 709 notmuch_query_count_threads_st (notmuch_query_t *query, unsigned *count)
 710 {
 711     notmuch_messages_t *messages;
 712     GHashTable *hash;
 713     notmuch_sort_t sort;
 714     notmuch_status_t ret = NOTMUCH_STATUS_SUCCESS;
 715
 716     sort = query->sort;
 717     query->sort = NOTMUCH_SORT_UNSORTED;
 718     ret = notmuch_query_search_messages_st (query, &messages);
 719     if (ret)
 720         return ret;
 721     query->sort = sort;
 722     if (messages == NULL)
 723         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 724
 725     hash = g_hash_table_new_full (g_str_hash, g_str_equal, NULL, NULL);
 726     if (hash == NULL) {
 727         talloc_free (messages);
 728         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 729     }
 730
 731     while (notmuch_messages_valid (messages)) {
 732         notmuch_message_t *message = notmuch_messages_get (messages);
 733         const char *thread_id = notmuch_message_get_thread_id (message);
 734         char *thread_id_copy = talloc_strdup (messages, thread_id);
 735         if (unlikely (thread_id_copy == NULL)) {
 736             notmuch_message_destroy (message);
 737             ret = NOTMUCH_STATUS_OUT_OF_MEMORY;
 738             goto DONE;
 739         }
 740         g_hash_table_insert (hash, thread_id_copy, NULL);
 741         notmuch_message_destroy (message);
 742         notmuch_messages_move_to_next (messages);
 743     }
 744
 745     *count = g_hash_table_size (hash);
 746
 747   DONE:
 748     g_hash_table_unref (hash);
 749     talloc_free (messages);
 750
 751     return ret;
 752 }
 753
 754 notmuch_database_t *
 755 notmuch_query_get_database (const notmuch_query_t *query)
 756 {
 757     return query->notmuch;
 758 }