xapian-core/backends/databasereplicator.h

   1 /** @file databasereplicator.h
   2  * @brief Class to manage replication of databases.
   3  */
   4 /* Copyright (C) 2008 Lemur Consulting Ltd
   5  * Copyright (C) 2009,2010 Olly Betts
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as
   9  * published by the Free Software Foundation; either version 2 of the
  10  * License, or (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
  20  * USA
  21  */
  22
  23 #ifndef XAPIAN_INCLUDED_DATABASEREPLICATOR_H
  24 #define XAPIAN_INCLUDED_DATABASEREPLICATOR_H
  25
  26 #include <string>
  27
  28 #include "xapian/types.h"
  29
  30 class RemoteConnection;
  31
  32 namespace Xapian {
  33
  34 /** Base class for database replicator objects.
  35  *
  36  *  This is subclassed by each database backend which supports replication.
  37  */
  38 class DatabaseReplicator {
  39     private:
  40         /// Copies are not allowed.
  41         DatabaseReplicator(const DatabaseReplicator &);
  42
  43         /// Assignment is not allowed.
  44         void operator=(const DatabaseReplicator &);
  45
  46     protected:
  47         /** Constructor to allow construction of subclasses from the open()
  48          *  method.
  49          */
  50         DatabaseReplicator() { }
  51
  52     public:
  53         /** Destroy the replicator.
  54          */
  55         virtual ~DatabaseReplicator();
  56
  57         /** Open a DatabaseReplicator for the given path.
  58          *
  59          *  The type of the database at the path is automatically detected.
  60          */
  61         static DatabaseReplicator * open(const std::string & path);
  62
  63         /** Check if the revision of the database is at least that of a target.
  64          *
  65          *  @param rev The database revision.
  66          *  @param target The target revision.
  67          */
  68         virtual bool check_revision_at_least(const std::string & rev,
  69                                              const std::string & target) const = 0;
  70
  71         /** Read and apply the next changeset.
  72          *
  73          *  @param conn The remote connection manager.
  74          *
  75          *  @param end_time The time to timeout at.
  76          *
  77          *  @param db_valid Whether the database is known to be valid at the
  78          *  start of the changeset.  If this is true, some additional checks
  79          *  are performed.
  80          */
  81         virtual std::string apply_changeset_from_conn(RemoteConnection & conn,
  82                                                       double end_time,
  83                                                       bool db_valid) const = 0;
  84
  85         /** Get a UUID for the replica.
  86          *
  87          *  If the UUID cannot be read (for example, because the database is
  88          *  not valid), this should return the empty string, rather than
  89          *  raising an exception.
  90          */
  91         virtual std::string get_uuid() const = 0;
  92 };
  93
  94 }
  95
  96 #endif /* XAPIAN_INCLUDED_DATABASEREPLICATOR_H */