xapian-letor/tests/harness/backendmanager_multi.cc

   1 /** @file backendmanager_multi.cc
   2  * @brief BackendManager subclass for multi databases.
   3  */
   4 /* Copyright (C) 2007,2008,2009,2011,2012,2013,2015 Olly Betts
   5  * Copyright (C) 2008 Lemur Consulting Ltd
   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 USA
  20  */
  21
  22 #include <config.h>
  23
  24 #include "backendmanager_multi.h"
  25
  26 #include "filetests.h"
  27 #include "index_utils.h"
  28 #include "str.h"
  29
  30 #include <cerrno>
  31 #include <cstdio> // For rename().
  32 #include <cstring>
  33
  34 using namespace std;
  35
  36 BackendManagerMulti::BackendManagerMulti(const std::string & subtype_)
  37         : subtype(subtype_)
  38 {
  39 #ifdef XAPIAN_HAS_GLASS_BACKEND
  40     if (subtype == "glass") return;
  41 #endif
  42     throw ("Unknown backend type \"" + subtype + "\" specified for multi database subdatabases");
  43 }
  44
  45 std::string
  46 BackendManagerMulti::get_dbtype() const
  47 {
  48     return "multi_" + subtype;
  49 }
  50
  51 #define NUMBER_OF_SUB_DBS 2
  52
  53 string
  54 BackendManagerMulti::createdb_multi(const vector<string> & files)
  55 {
  56     string dbdir = ".multi" + subtype;
  57     create_dir_if_needed(dbdir);
  58
  59     string dbname = "db";
  60     vector<string>::const_iterator i;
  61     for (i = files.begin(); i != files.end(); ++i) {
  62         dbname += "__";
  63         dbname += *i;
  64     }
  65     string dbpath = dbdir + "/" + dbname;
  66
  67     if (file_exists(dbpath)) return dbpath;
  68
  69     string tmpfile = dbpath;
  70     tmpfile += ".tmp";
  71     ofstream out(tmpfile.c_str());
  72     if (!out.is_open()) {
  73         string msg = "Couldn't create file '";
  74         msg += tmpfile;
  75         msg += "' (";
  76         msg += strerror(errno);
  77         msg += ')';
  78         throw msg;
  79     }
  80
  81     // Open NUMBER_OF_SUB_DBS databases and index files to them alternately so
  82     // a multi-db combining them contains the documents in the expected order.
  83     Xapian::WritableDatabase dbs;
  84     int flags = Xapian::DB_CREATE_OR_OVERWRITE;
  85     if (subtype == "glass") {
  86         flags |= Xapian::DB_BACKEND_GLASS;
  87     } else {
  88         string msg = "Unknown multidb subtype: ";
  89         msg += subtype;
  90         throw msg;
  91     }
  92     string dbbase = dbdir;
  93     dbbase += '/';
  94     dbbase += dbname;
  95     dbbase += "___";
  96     size_t dbbase_len = dbbase.size();
  97     string line = subtype;
  98     line += ' ';
  99     line += dbname;
 100     line += "___";
 101     for (size_t n = 0; n < NUMBER_OF_SUB_DBS; ++n) {
 102         dbbase += str(n);
 103         dbs.add_database(Xapian::WritableDatabase(dbbase, flags));
 104         dbbase.resize(dbbase_len);
 105         out << line << n << '\n';
 106     }
 107     out.close();
 108
 109     FileIndexer(get_datadir(), files).index_to(dbs);
 110
 111     rename(tmpfile.c_str(), dbpath.c_str());
 112
 113     return dbpath;
 114 }
 115
 116 string
 117 BackendManagerMulti::do_get_database_path(const vector<string> & files)
 118 {
 119     return createdb_multi(files);
 120 }
 121
 122 Xapian::WritableDatabase
 123 BackendManagerMulti::get_writable_database(const string &, const string &)
 124 {
 125     throw Xapian::UnimplementedError("Multi-databases don't support writing");
 126 }