xapian-core/matcher/remotesubmatch.h

   1 /** @file remotesubmatch.h
   2  *  @brief SubMatch class for a remote database.
   3  */
   4 /* Copyright (C) 2006,2007,2009,2011,2014,2015 Olly Betts
   5  * Copyright (C) 2007,2008 Lemur Consulting Ltd
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  20  */
  21
  22 #ifndef XAPIAN_INCLUDED_REMOTESUBMATCH_H
  23 #define XAPIAN_INCLUDED_REMOTESUBMATCH_H
  24
  25 #include "backends/remote/remote-database.h"
  26 #include "xapian/weight.h"
  27
  28 namespace Xapian {
  29     class MatchSpy;
  30 }
  31
  32 /// Class for performing matching on a remote database.
  33 class RemoteSubMatch {
  34     /// Don't allow assignment.
  35     RemoteSubMatch& operator=(const RemoteSubMatch &) = delete;
  36
  37     /// Don't allow copying.
  38     RemoteSubMatch(const RemoteSubMatch &) = delete;
  39
  40     /// The remote database.
  41     const RemoteDatabase *db;
  42
  43     typedef Xapian::Internal::opt_intrusive_ptr<Xapian::MatchSpy> opt_ptr_spy;
  44
  45     /// The matchspies to use.
  46     const std::vector<opt_ptr_spy>& matchspies;
  47
  48   public:
  49     /// Constructor.
  50     RemoteSubMatch(const RemoteDatabase *db_,
  51                    const std::vector<opt_ptr_spy>& matchspies);
  52
  53     /** Fetch and collate statistics.
  54      *
  55      *  Before we can calculate term weights we need to fetch statistics from
  56      *  each database involved and collate them.
  57      *
  58      *  @param block    A RemoteSubMatch may not be able to report statistics
  59      *                  when first asked.  If block is false, it will return
  60      *                  false in this situation allowing the matcher to prepare
  61      *                  other submatches.  If block is true, then this method
  62      *                  will block until statistics are available.
  63      *
  64      *  @param total_stats A stats object to which the statistics should be
  65      *                  added.
  66      *
  67      *  @return         If block is false and results aren't available yet
  68      *                  then false will be returned and this method must be
  69      *                  called again before the match can proceed.  If results
  70      *                  are available or block is true, then this method
  71      *                  returns true.
  72      */
  73     bool prepare_match(bool block, Xapian::Weight::Internal& total_stats);
  74
  75     /** Start the match.
  76      *
  77      *  @param first          The first item in the result set to return.
  78      *  @param maxitems       The maximum number of items to return.
  79      *  @param check_at_least The minimum number of items to check.
  80      *  @param total_stats    The total statistics for the collection.
  81      */
  82     void start_match(Xapian::doccount first,
  83                      Xapian::doccount maxitems,
  84                      Xapian::doccount check_at_least,
  85                      Xapian::Weight::Internal& total_stats);
  86
  87     /// Get MSet.
  88     Xapian::MSet get_mset() { return db->get_mset(matchspies); }
  89 };
  90
  91 #endif /* XAPIAN_INCLUDED_REMOTESUBMATCH_H */