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   1 /* query.cc - Support for searching a notmuch database
   2  *
   3  * Copyright © 2009 Carl Worth
   4  *
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation, either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see https://www.gnu.org/licenses/ .
  17  *
  18  * Author: Carl Worth <cworth@cworth.org>
  19  */
  20
  21 #include "notmuch-private.h"
  22 #include "database-private.h"
  23
  24 #include <glib.h> /* GHashTable, GPtrArray */
  25
  26 #if HAVE_SFSEXP
  27 #include "sexp.h"
  28 #endif
  29
  30 struct _notmuch_query {
  31     notmuch_database_t *notmuch;
  32     const char *query_string;
  33     notmuch_sort_t sort;
  34     notmuch_string_list_t *exclude_terms;
  35     notmuch_exclude_t omit_excluded;
  36     bool parsed;
  37     notmuch_query_syntax_t syntax;
  38     Xapian::Query xapian_query;
  39     std::set<std::string> terms;
  40 };
  41
  42 typedef struct _notmuch_mset_messages {
  43     notmuch_messages_t base;
  44     notmuch_database_t *notmuch;
  45     Xapian::MSetIterator iterator;
  46     Xapian::MSetIterator iterator_end;
  47 } notmuch_mset_messages_t;
  48
  49 struct _notmuch_doc_id_set {
  50     unsigned char *bitmap;
  51     unsigned int bound;
  52 };
  53
  54 #define DOCIDSET_WORD(bit) ((bit) / CHAR_BIT)
  55 #define DOCIDSET_BIT(bit) ((bit) % CHAR_BIT)
  56
  57 struct _notmuch_threads {
  58     notmuch_query_t *query;
  59
  60     /* The ordered list of doc ids matched by the query. */
  61     GArray *doc_ids;
  62     /* Our iterator's current position in doc_ids. */
  63     unsigned int doc_id_pos;
  64     /* The set of matched docid's that have not been assigned to a
  65      * thread. Initially, this contains every docid in doc_ids. */
  66     notmuch_doc_id_set_t match_set;
  67 };
  68
  69 /* We need this in the message functions so forward declare. */
  70 static bool
  71 _notmuch_doc_id_set_init (void *ctx,
  72                           notmuch_doc_id_set_t *doc_ids,
  73                           GArray *arr);
  74
  75 static bool
  76 _debug_query (void)
  77 {
  78     char *env = getenv ("NOTMUCH_DEBUG_QUERY");
  79
  80     return (env && strcmp (env, "") != 0);
  81 }
  82
  83 /* Explicit destructor call for placement new */
  84 static int
  85 _notmuch_query_destructor (notmuch_query_t *query)
  86 {
  87     query->xapian_query.~Query();
  88     query->terms.~set<std::string>();
  89     return 0;
  90 }
  91
  92 static notmuch_query_t *
  93 _notmuch_query_constructor (notmuch_database_t *notmuch,
  94                             const char *query_string)
  95 {
  96     notmuch_query_t *query;
  97
  98     if (_debug_query ())
  99         fprintf (stderr, "Query string is:\n%s\n", query_string);
 100
 101     query = talloc (notmuch, notmuch_query_t);
 102     if (unlikely (query == NULL))
 103         return NULL;
 104
 105     new (&query->xapian_query) Xapian::Query ();
 106     new (&query->terms) std::set<std::string> ();
 107     query->parsed = false;
 108
 109     talloc_set_destructor (query, _notmuch_query_destructor);
 110
 111     query->notmuch = notmuch;
 112
 113     if (query_string)
 114         query->query_string = talloc_strdup (query, query_string);
 115     else
 116         query->query_string = NULL;
 117
 118     query->sort = NOTMUCH_SORT_NEWEST_FIRST;
 119
 120     query->exclude_terms = _notmuch_string_list_create (query);
 121
 122     query->omit_excluded = NOTMUCH_EXCLUDE_TRUE;
 123
 124     return query;
 125 }
 126
 127 notmuch_query_t *
 128 notmuch_query_create (notmuch_database_t *notmuch,
 129                       const char *query_string)
 130 {
 131
 132     notmuch_query_t *query;
 133     notmuch_status_t status;
 134
 135     status = notmuch_query_create_with_syntax (notmuch, query_string,
 136                                                NOTMUCH_QUERY_SYNTAX_XAPIAN,
 137                                                &query);
 138     if (status)
 139         return NULL;
 140
 141     return query;
 142 }
 143
 144 notmuch_status_t
 145 notmuch_query_create_with_syntax (notmuch_database_t *notmuch,
 146                                   const char *query_string,
 147                                   notmuch_query_syntax_t syntax,
 148                                   notmuch_query_t **output)
 149 {
 150
 151     notmuch_query_t *query;
 152
 153     if (! output)
 154         return NOTMUCH_STATUS_NULL_POINTER;
 155
 156     query = _notmuch_query_constructor (notmuch, query_string);
 157     if (! query)
 158         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 159
 160     if (syntax == NOTMUCH_QUERY_SYNTAX_SEXP && ! HAVE_SFSEXP) {
 161         _notmuch_database_log (notmuch, "sexp query parser not available");
 162         return NOTMUCH_STATUS_ILLEGAL_ARGUMENT;
 163     }
 164
 165     query->syntax = syntax;
 166
 167     *output = query;
 168
 169     return NOTMUCH_STATUS_SUCCESS;
 170 }
 171
 172 static notmuch_status_t
 173 _notmuch_query_ensure_parsed_xapian (notmuch_query_t *query)
 174 {
 175     try {
 176         query->xapian_query =
 177             query->notmuch->query_parser->
 178             parse_query (query->query_string, NOTMUCH_QUERY_PARSER_FLAGS);
 179
 180         /* Xapian doesn't support skip_to on terms from a query since
 181          *  they are unordered, so cache a copy of all terms in
 182          *  something searchable.
 183          */
 184
 185         for (Xapian::TermIterator t = query->xapian_query.get_terms_begin ();
 186              t != query->xapian_query.get_terms_end (); ++t)
 187             query->terms.insert (*t);
 188
 189         query->parsed = true;
 190
 191     } catch (const Xapian::Error &error) {
 192         if (! query->notmuch->exception_reported) {
 193             _notmuch_database_log (query->notmuch,
 194                                    "A Xapian exception occurred parsing query: %s\n",
 195                                    error.get_msg ().c_str ());
 196             _notmuch_database_log_append (query->notmuch,
 197                                           "Query string was: %s\n",
 198                                           query->query_string);
 199             query->notmuch->exception_reported = true;
 200         }
 201
 202         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 203     }
 204     return NOTMUCH_STATUS_SUCCESS;
 205 }
 206
 207 static notmuch_status_t
 208 _notmuch_query_ensure_parsed_sexpr (notmuch_query_t *query)
 209 {
 210     if (query->parsed)
 211         return NOTMUCH_STATUS_SUCCESS;
 212
 213     query->xapian_query = Xapian::Query::MatchAll;
 214     return NOTMUCH_STATUS_SUCCESS;
 215 }
 216
 217 static notmuch_status_t
 218 _notmuch_query_ensure_parsed (notmuch_query_t *query)
 219 {
 220     if (query->parsed)
 221         return NOTMUCH_STATUS_SUCCESS;
 222
 223 #if HAVE_SFSEXP
 224     if (query->syntax == NOTMUCH_QUERY_SYNTAX_SEXP)
 225         return _notmuch_query_ensure_parsed_sexpr (query);
 226 #endif
 227
 228     return _notmuch_query_ensure_parsed_xapian (query);
 229 }
 230
 231 const char *
 232 notmuch_query_get_query_string (const notmuch_query_t *query)
 233 {
 234     return query->query_string;
 235 }
 236
 237 void
 238 notmuch_query_set_omit_excluded (notmuch_query_t *query,
 239                                  notmuch_exclude_t omit_excluded)
 240 {
 241     query->omit_excluded = omit_excluded;
 242 }
 243
 244 void
 245 notmuch_query_set_sort (notmuch_query_t *query, notmuch_sort_t sort)
 246 {
 247     query->sort = sort;
 248 }
 249
 250 notmuch_sort_t
 251 notmuch_query_get_sort (const notmuch_query_t *query)
 252 {
 253     return query->sort;
 254 }
 255
 256 notmuch_status_t
 257 notmuch_query_add_tag_exclude (notmuch_query_t *query, const char *tag)
 258 {
 259     notmuch_status_t status;
 260     char *term;
 261
 262     status = _notmuch_query_ensure_parsed (query);
 263     if (status)
 264         return status;
 265
 266     term = talloc_asprintf (query, "%s%s", _find_prefix ("tag"), tag);
 267     if (query->terms.count (term) != 0)
 268         return NOTMUCH_STATUS_IGNORED;
 269
 270     _notmuch_string_list_append (query->exclude_terms, term);
 271     return NOTMUCH_STATUS_SUCCESS;
 272 }
 273
 274 /* We end up having to call the destructors explicitly because we had
 275  * to use "placement new" in order to initialize C++ objects within a
 276  * block that we allocated with talloc. So C++ is making talloc
 277  * slightly less simple to use, (we wouldn't need
 278  * talloc_set_destructor at all otherwise).
 279  */
 280 static int
 281 _notmuch_messages_destructor (notmuch_mset_messages_t *messages)
 282 {
 283     messages->iterator.~MSetIterator ();
 284     messages->iterator_end.~MSetIterator ();
 285
 286     return 0;
 287 }
 288
 289 /* Return a query that matches messages with the excluded tags
 290  * registered with query. The caller of this function has to combine the returned
 291  * query appropriately.*/
 292 static Xapian::Query
 293 _notmuch_exclude_tags (notmuch_query_t *query)
 294 {
 295     Xapian::Query exclude_query = Xapian::Query::MatchNothing;
 296
 297     for (notmuch_string_node_t *term = query->exclude_terms->head; term;
 298          term = term->next) {
 299         exclude_query = Xapian::Query (Xapian::Query::OP_OR,
 300                                        exclude_query, Xapian::Query (term->string));
 301     }
 302     return exclude_query;
 303 }
 304
 305
 306 notmuch_status_t
 307 notmuch_query_search_messages_st (notmuch_query_t *query,
 308                                   notmuch_messages_t **out)
 309 {
 310     return notmuch_query_search_messages (query, out);
 311 }
 312
 313 notmuch_status_t
 314 notmuch_query_search_messages (notmuch_query_t *query,
 315                                notmuch_messages_t **out)
 316 {
 317     return _notmuch_query_search_documents (query, "mail", out);
 318 }
 319
 320 notmuch_status_t
 321 _notmuch_query_search_documents (notmuch_query_t *query,
 322                                  const char *type,
 323                                  notmuch_messages_t **out)
 324 {
 325     notmuch_database_t *notmuch = query->notmuch;
 326     const char *query_string = query->query_string;
 327     notmuch_mset_messages_t *messages;
 328     notmuch_status_t status;
 329
 330     status = _notmuch_query_ensure_parsed (query);
 331     if (status)
 332         return status;
 333
 334     messages = talloc (query, notmuch_mset_messages_t);
 335     if (unlikely (messages == NULL))
 336         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 337
 338     try {
 339
 340         messages->base.is_of_list_type = false;
 341         messages->base.iterator = NULL;
 342         messages->notmuch = notmuch;
 343         new (&messages->iterator) Xapian::MSetIterator ();
 344         new (&messages->iterator_end) Xapian::MSetIterator ();
 345
 346         talloc_set_destructor (messages, _notmuch_messages_destructor);
 347
 348         Xapian::Enquire enquire (*notmuch->xapian_db);
 349         Xapian::Query mail_query (talloc_asprintf (query, "%s%s",
 350                                                    _find_prefix ("type"),
 351                                                    type));
 352         Xapian::Query final_query, exclude_query;
 353         Xapian::MSet mset;
 354         Xapian::MSetIterator iterator;
 355
 356         if (strcmp (query_string, "") == 0 ||
 357             strcmp (query_string, "*") == 0) {
 358             final_query = mail_query;
 359         } else {
 360             final_query = Xapian::Query (Xapian::Query::OP_AND,
 361                                          mail_query, query->xapian_query);
 362         }
 363         messages->base.excluded_doc_ids = NULL;
 364
 365         if ((query->omit_excluded != NOTMUCH_EXCLUDE_FALSE) && (query->exclude_terms)) {
 366             exclude_query = _notmuch_exclude_tags (query);
 367
 368             if (query->omit_excluded == NOTMUCH_EXCLUDE_TRUE ||
 369                 query->omit_excluded == NOTMUCH_EXCLUDE_ALL) {
 370                 final_query = Xapian::Query (Xapian::Query::OP_AND_NOT,
 371                                              final_query, exclude_query);
 372             } else { /* NOTMUCH_EXCLUDE_FLAG */
 373                 exclude_query = Xapian::Query (Xapian::Query::OP_AND,
 374                                                exclude_query, final_query);
 375
 376                 enquire.set_weighting_scheme (Xapian::BoolWeight ());
 377                 enquire.set_query (exclude_query);
 378
 379                 mset = enquire.get_mset (0, notmuch->xapian_db->get_doccount ());
 380
 381                 GArray *excluded_doc_ids = g_array_new (false, false, sizeof (unsigned int));
 382
 383                 for (iterator = mset.begin (); iterator != mset.end (); iterator++) {
 384                     unsigned int doc_id = *iterator;
 385                     g_array_append_val (excluded_doc_ids, doc_id);
 386                 }
 387                 messages->base.excluded_doc_ids = talloc (messages, _notmuch_doc_id_set);
 388                 _notmuch_doc_id_set_init (query, messages->base.excluded_doc_ids,
 389                                           excluded_doc_ids);
 390                 g_array_unref (excluded_doc_ids);
 391             }
 392         }
 393
 394
 395         enquire.set_weighting_scheme (Xapian::BoolWeight ());
 396
 397         switch (query->sort) {
 398         case NOTMUCH_SORT_OLDEST_FIRST:
 399             enquire.set_sort_by_value (NOTMUCH_VALUE_TIMESTAMP, false);
 400             break;
 401         case NOTMUCH_SORT_NEWEST_FIRST:
 402             enquire.set_sort_by_value (NOTMUCH_VALUE_TIMESTAMP, true);
 403             break;
 404         case NOTMUCH_SORT_MESSAGE_ID:
 405             enquire.set_sort_by_value (NOTMUCH_VALUE_MESSAGE_ID, false);
 406             break;
 407         case NOTMUCH_SORT_UNSORTED:
 408             break;
 409         }
 410
 411         if (_debug_query ()) {
 412             fprintf (stderr, "Exclude query is:\n%s\n",
 413                      exclude_query.get_description ().c_str ());
 414             fprintf (stderr, "Final query is:\n%s\n",
 415                      final_query.get_description ().c_str ());
 416         }
 417
 418         enquire.set_query (final_query);
 419
 420         mset = enquire.get_mset (0, notmuch->xapian_db->get_doccount ());
 421
 422         messages->iterator = mset.begin ();
 423         messages->iterator_end = mset.end ();
 424
 425         *out = &messages->base;
 426         return NOTMUCH_STATUS_SUCCESS;
 427
 428     } catch (const Xapian::Error &error) {
 429         _notmuch_database_log (notmuch,
 430                                "A Xapian exception occurred performing query: %s\n",
 431                                error.get_msg ().c_str ());
 432         _notmuch_database_log_append (notmuch,
 433                                       "Query string was: %s\n",
 434                                       query->query_string);
 435
 436         notmuch->exception_reported = true;
 437         talloc_free (messages);
 438         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 439     }
 440 }
 441
 442 bool
 443 _notmuch_mset_messages_valid (notmuch_messages_t *messages)
 444 {
 445     notmuch_mset_messages_t *mset_messages;
 446
 447     mset_messages = (notmuch_mset_messages_t *) messages;
 448
 449     return (mset_messages->iterator != mset_messages->iterator_end);
 450 }
 451
 452 static Xapian::docid
 453 _notmuch_mset_messages_get_doc_id (notmuch_messages_t *messages)
 454 {
 455     notmuch_mset_messages_t *mset_messages;
 456
 457     mset_messages = (notmuch_mset_messages_t *) messages;
 458
 459     if (! _notmuch_mset_messages_valid (&mset_messages->base))
 460         return 0;
 461
 462     return *mset_messages->iterator;
 463 }
 464
 465 notmuch_message_t *
 466 _notmuch_mset_messages_get (notmuch_messages_t *messages)
 467 {
 468     notmuch_message_t *message;
 469     Xapian::docid doc_id;
 470     notmuch_private_status_t status;
 471     notmuch_mset_messages_t *mset_messages;
 472
 473     mset_messages = (notmuch_mset_messages_t *) messages;
 474
 475     if (! _notmuch_mset_messages_valid (&mset_messages->base))
 476         return NULL;
 477
 478     doc_id = *mset_messages->iterator;
 479
 480     message = _notmuch_message_create (mset_messages,
 481                                        mset_messages->notmuch, doc_id,
 482                                        &status);
 483
 484     if (message == NULL &&
 485         status == NOTMUCH_PRIVATE_STATUS_NO_DOCUMENT_FOUND) {
 486         INTERNAL_ERROR ("a messages iterator contains a non-existent document ID.\n");
 487     }
 488
 489     if (messages->excluded_doc_ids &&
 490         _notmuch_doc_id_set_contains (messages->excluded_doc_ids, doc_id))
 491         notmuch_message_set_flag (message, NOTMUCH_MESSAGE_FLAG_EXCLUDED, true);
 492
 493     return message;
 494 }
 495
 496 void
 497 _notmuch_mset_messages_move_to_next (notmuch_messages_t *messages)
 498 {
 499     notmuch_mset_messages_t *mset_messages;
 500
 501     mset_messages = (notmuch_mset_messages_t *) messages;
 502
 503     mset_messages->iterator++;
 504 }
 505
 506 static bool
 507 _notmuch_doc_id_set_init (void *ctx,
 508                           notmuch_doc_id_set_t *doc_ids,
 509                           GArray *arr)
 510 {
 511     unsigned int max = 0;
 512     unsigned char *bitmap;
 513
 514     for (unsigned int i = 0; i < arr->len; i++)
 515         max = MAX (max, g_array_index (arr, unsigned int, i));
 516     bitmap = talloc_zero_array (ctx, unsigned char, DOCIDSET_WORD (max) + 1);
 517
 518     if (bitmap == NULL)
 519         return false;
 520
 521     doc_ids->bitmap = bitmap;
 522     doc_ids->bound = max + 1;
 523
 524     for (unsigned int i = 0; i < arr->len; i++) {
 525         unsigned int doc_id = g_array_index (arr, unsigned int, i);
 526         bitmap[DOCIDSET_WORD (doc_id)] |= 1 << DOCIDSET_BIT (doc_id);
 527     }
 528
 529     return true;
 530 }
 531
 532 bool
 533 _notmuch_doc_id_set_contains (notmuch_doc_id_set_t *doc_ids,
 534                               unsigned int doc_id)
 535 {
 536     if (doc_id >= doc_ids->bound)
 537         return false;
 538     return doc_ids->bitmap[DOCIDSET_WORD (doc_id)] & (1 << DOCIDSET_BIT (doc_id));
 539 }
 540
 541 void
 542 _notmuch_doc_id_set_remove (notmuch_doc_id_set_t *doc_ids,
 543                             unsigned int doc_id)
 544 {
 545     if (doc_id < doc_ids->bound)
 546         doc_ids->bitmap[DOCIDSET_WORD (doc_id)] &= ~(1 << DOCIDSET_BIT (doc_id));
 547 }
 548
 549 /* Glib objects force use to use a talloc destructor as well, (but not
 550  * nearly as ugly as the for messages due to C++ objects). At
 551  * this point, I'd really like to have some talloc-friendly
 552  * equivalents for the few pieces of glib that I'm using. */
 553 static int
 554 _notmuch_threads_destructor (notmuch_threads_t *threads)
 555 {
 556     if (threads->doc_ids)
 557         g_array_unref (threads->doc_ids);
 558
 559     return 0;
 560 }
 561
 562 notmuch_status_t
 563 notmuch_query_search_threads_st (notmuch_query_t *query, notmuch_threads_t **out)
 564 {
 565     return notmuch_query_search_threads (query, out);
 566 }
 567
 568 notmuch_status_t
 569 notmuch_query_search_threads (notmuch_query_t *query,
 570                               notmuch_threads_t **out)
 571 {
 572     notmuch_threads_t *threads;
 573     notmuch_messages_t *messages;
 574     notmuch_status_t status;
 575
 576     threads = talloc (query, notmuch_threads_t);
 577     if (threads == NULL)
 578         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 579     threads->doc_ids = NULL;
 580     talloc_set_destructor (threads, _notmuch_threads_destructor);
 581
 582     threads->query = query;
 583
 584     status = notmuch_query_search_messages (query, &messages);
 585     if (status) {
 586         talloc_free (threads);
 587         return status;
 588     }
 589
 590     threads->doc_ids = g_array_new (false, false, sizeof (unsigned int));
 591     while (notmuch_messages_valid (messages)) {
 592         unsigned int doc_id = _notmuch_mset_messages_get_doc_id (messages);
 593         g_array_append_val (threads->doc_ids, doc_id);
 594         notmuch_messages_move_to_next (messages);
 595     }
 596     threads->doc_id_pos = 0;
 597
 598     talloc_free (messages);
 599
 600     if (! _notmuch_doc_id_set_init (threads, &threads->match_set,
 601                                     threads->doc_ids)) {
 602         talloc_free (threads);
 603         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 604     }
 605
 606     *out = threads;
 607     return NOTMUCH_STATUS_SUCCESS;
 608 }
 609
 610 void
 611 notmuch_query_destroy (notmuch_query_t *query)
 612 {
 613     talloc_free (query);
 614 }
 615
 616 notmuch_bool_t
 617 notmuch_threads_valid (notmuch_threads_t *threads)
 618 {
 619     unsigned int doc_id;
 620
 621     if (! threads)
 622         return false;
 623
 624     while (threads->doc_id_pos < threads->doc_ids->len) {
 625         doc_id = g_array_index (threads->doc_ids, unsigned int,
 626                                 threads->doc_id_pos);
 627         if (_notmuch_doc_id_set_contains (&threads->match_set, doc_id))
 628             break;
 629
 630         threads->doc_id_pos++;
 631     }
 632
 633     return threads->doc_id_pos < threads->doc_ids->len;
 634 }
 635
 636 notmuch_thread_t *
 637 notmuch_threads_get (notmuch_threads_t *threads)
 638 {
 639     unsigned int doc_id;
 640
 641     if (! notmuch_threads_valid (threads))
 642         return NULL;
 643
 644     doc_id = g_array_index (threads->doc_ids, unsigned int,
 645                             threads->doc_id_pos);
 646     return _notmuch_thread_create (threads->query,
 647                                    threads->query->notmuch,
 648                                    doc_id,
 649                                    &threads->match_set,
 650                                    threads->query->exclude_terms,
 651                                    threads->query->omit_excluded,
 652                                    threads->query->sort);
 653 }
 654
 655 void
 656 notmuch_threads_move_to_next (notmuch_threads_t *threads)
 657 {
 658     threads->doc_id_pos++;
 659 }
 660
 661 void
 662 notmuch_threads_destroy (notmuch_threads_t *threads)
 663 {
 664     talloc_free (threads);
 665 }
 666
 667 notmuch_status_t
 668 notmuch_query_count_messages_st (notmuch_query_t *query, unsigned *count_out)
 669 {
 670     return notmuch_query_count_messages (query, count_out);
 671 }
 672
 673 notmuch_status_t
 674 notmuch_query_count_messages (notmuch_query_t *query, unsigned *count_out)
 675 {
 676     return _notmuch_query_count_documents (query, "mail", count_out);
 677 }
 678
 679 notmuch_status_t
 680 _notmuch_query_count_documents (notmuch_query_t *query, const char *type, unsigned *count_out)
 681 {
 682     notmuch_database_t *notmuch = query->notmuch;
 683     const char *query_string = query->query_string;
 684     Xapian::doccount count = 0;
 685     notmuch_status_t status;
 686
 687     status = _notmuch_query_ensure_parsed (query);
 688     if (status)
 689         return status;
 690
 691     try {
 692         Xapian::Enquire enquire (*notmuch->xapian_db);
 693         Xapian::Query mail_query (talloc_asprintf (query, "%s%s",
 694                                                    _find_prefix ("type"),
 695                                                    type));
 696         Xapian::Query final_query, exclude_query;
 697         Xapian::MSet mset;
 698
 699         if (strcmp (query_string, "") == 0 ||
 700             strcmp (query_string, "*") == 0) {
 701             final_query = mail_query;
 702         } else {
 703             final_query = Xapian::Query (Xapian::Query::OP_AND,
 704                                          mail_query, query->xapian_query);
 705         }
 706
 707         exclude_query = _notmuch_exclude_tags (query);
 708
 709         final_query = Xapian::Query (Xapian::Query::OP_AND_NOT,
 710                                      final_query, exclude_query);
 711
 712         enquire.set_weighting_scheme (Xapian::BoolWeight ());
 713         enquire.set_docid_order (Xapian::Enquire::ASCENDING);
 714
 715         if (_debug_query ()) {
 716             fprintf (stderr, "Exclude query is:\n%s\n",
 717                      exclude_query.get_description ().c_str ());
 718             fprintf (stderr, "Final query is:\n%s\n",
 719                      final_query.get_description ().c_str ());
 720         }
 721
 722         enquire.set_query (final_query);
 723
 724         /*
 725          * Set the checkatleast parameter to the number of documents
 726          * in the database to make get_matches_estimated() exact.
 727          * Set the max parameter to 1 to avoid fetching documents we will discard.
 728          */
 729         mset = enquire.get_mset (0, 1,
 730                                  notmuch->xapian_db->get_doccount ());
 731
 732         count = mset.get_matches_estimated ();
 733
 734     } catch (const Xapian::Error &error) {
 735         _notmuch_database_log (notmuch,
 736                                "A Xapian exception occurred performing query: %s\n",
 737                                error.get_msg ().c_str ());
 738         _notmuch_database_log_append (notmuch,
 739                                       "Query string was: %s\n",
 740                                       query->query_string);
 741         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 742     }
 743
 744     *count_out = count;
 745     return NOTMUCH_STATUS_SUCCESS;
 746 }
 747
 748 notmuch_status_t
 749 notmuch_query_count_threads_st (notmuch_query_t *query, unsigned *count)
 750 {
 751     return notmuch_query_count_threads (query, count);
 752 }
 753
 754 notmuch_status_t
 755 notmuch_query_count_threads (notmuch_query_t *query, unsigned *count)
 756 {
 757     notmuch_messages_t *messages;
 758     GHashTable *hash;
 759     notmuch_sort_t sort;
 760     notmuch_status_t ret = NOTMUCH_STATUS_SUCCESS;
 761
 762     sort = query->sort;
 763     query->sort = NOTMUCH_SORT_UNSORTED;
 764     ret = notmuch_query_search_messages (query, &messages);
 765     if (ret)
 766         return ret;
 767     query->sort = sort;
 768     if (messages == NULL)
 769         return NOTMUCH_STATUS_XAPIAN_EXCEPTION;
 770
 771     hash = g_hash_table_new_full (g_str_hash, g_str_equal, NULL, NULL);
 772     if (hash == NULL) {
 773         talloc_free (messages);
 774         return NOTMUCH_STATUS_OUT_OF_MEMORY;
 775     }
 776
 777     while (notmuch_messages_valid (messages)) {
 778         notmuch_message_t *message = notmuch_messages_get (messages);
 779         const char *thread_id = notmuch_message_get_thread_id (message);
 780         char *thread_id_copy = talloc_strdup (messages, thread_id);
 781         if (unlikely (thread_id_copy == NULL)) {
 782             notmuch_message_destroy (message);
 783             ret = NOTMUCH_STATUS_OUT_OF_MEMORY;
 784             goto DONE;
 785         }
 786         g_hash_table_insert (hash, thread_id_copy, NULL);
 787         notmuch_message_destroy (message);
 788         notmuch_messages_move_to_next (messages);
 789     }
 790
 791     *count = g_hash_table_size (hash);
 792
 793   DONE:
 794     g_hash_table_unref (hash);
 795     talloc_free (messages);
 796
 797     return ret;
 798 }
 799
 800 notmuch_database_t *
 801 notmuch_query_get_database (const notmuch_query_t *query)
 802 {
 803     return query->notmuch;
 804 }