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1 =head1 LICENSE
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2
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3 Copyright (c) 1999-2012 The European Bioinformatics Institute and
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4 Genome Research Limited. All rights reserved.
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5
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6 This software is distributed under a modified Apache license.
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7 For license details, please see
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8
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9 http://www.ensembl.org/info/about/code_licence.html
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10
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11 =head1 CONTACT
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12
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13 Please email comments or questions to the public Ensembl
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14 developers list at <dev@ensembl.org>.
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15
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16 Questions may also be sent to the Ensembl help desk at
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17 <helpdesk@ensembl.org>.
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18
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19 =cut
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20
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21 =head1 NAME
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22
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23 Bio::EnsEMBL::DBSQL::ProxyDBConnection - Database connection wrapper allowing
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24 for one backing connection to be used for multiple DBs
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25
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26 =head1 SYNOPSIS
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27
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28 my $dbc = Bio::EnsEMBL::DBSQL::DBConnection->new(-HOST => 'host', -PORT => 3306, -USER => 'user');
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29 my $p_h_dbc = Bio::EnsEMBL::DBSQL::ProxyDBConnection->new(-DBC => $dbc, -DBNAME => 'human');
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30 my $p_m_dbc = Bio::EnsEMBL::DBSQL::ProxyDBConnection->new(-DBC => $dbc, -DBNAME => 'mouse');
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31
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32 =head1 DESCRIPTION
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33
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34 This class is used to maintain one active connection to a database whilst it
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35 appears to be working against multiple schemas. It does this by checking the
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36 currently connected database before performing any query which could require
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37 a database change such as prepare.
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38
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39 This class is only intended for internal use so please do not use unless
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40 you are aware of what it will do and what the consequences of its usage are.
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41
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42 =head1 METHODS
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43
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44 =cut
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45
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46 package Bio::EnsEMBL::DBSQL::ProxyDBConnection;
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47
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48 use strict;
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49 use warnings;
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50
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51 use Bio::EnsEMBL::Utils::Exception qw/warning/;
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52 use Bio::EnsEMBL::Utils::Argument qw/rearrange/;
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53
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54 use base qw/Bio::EnsEMBL::Utils::Proxy/;
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55
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56 sub new {
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57 my ($class, @args) = @_;
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58 my ($dbc, $dbname) = rearrange([qw/DBC DBNAME/], @args);
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59 my $self = $class->SUPER::new($dbc);
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60 $self->dbname($dbname);
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61 return $self;
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62 }
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63
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64 =head2 switch_database
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65
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66 Description : Performs a switch of the backing DBConnection if the currently
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67 connected database is not the same as the database this proxy
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68 wants to connect to. It currently supports MySQL, Oracle and
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69 Postges switches is untested with all bar MySQL. If it
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70 cannot do a live DB/schema switch then it will disconnect
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71 the connection and then wait for the next process to
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72 connect therefore switching the DB.
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73 Exceptions : None but will warn if you attempt to switch a DB with
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74 active kids attached to the proxied database handle.
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75
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76 =cut
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77
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78 sub switch_database {
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79 my ($self) = @_;
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80 my $proxy = $self->__proxy();
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81 my $backing_dbname = $proxy->dbname();
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82 my $dbname = $self->dbname();
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83
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84 my $switch = 0;
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85 if(defined $dbname) {
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86 if(defined $backing_dbname) {
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87 $switch = ($dbname ne $backing_dbname) ? 1 : 0;
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88 }
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89 else {
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90 $switch = 1;
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91 }
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92 }
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93 else {
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94 $switch = 1 if defined $backing_dbname;
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95 }
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96
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97 if($switch) {
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98 $proxy->dbname($dbname);
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99 if($proxy->connected()) {
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100 my $kids = $proxy->db_handle()->{Kids};
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101 my $driver = lc($proxy->driver());
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102 #Edit to add other DB switching strategies on a per driver basis
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103 if($driver eq 'mysql') {
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104 $proxy->do('use '.$dbname);
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105 }
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106 elsif($driver eq 'oracle') {
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107 $proxy->do('ALTER SESSION SET CURRENT_SCHEMA = '.$dbname);
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108 }
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109 elsif($driver eq 'pg') {
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110 $proxy->do('set search_path to '.$dbname);
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111 }
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112 else {
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113 if($kids > 0) {
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114 warning "Attempting a database switch from '$backing_dbname' to '$dbname' with $kids active handle(s). Check your logic or do not use a ProxyDBConnection";
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115 }
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116 $proxy->disconnect_if_idle();
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117 }
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118 }
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119 }
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120
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121 return $switch;
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122 }
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123
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124 sub dbname {
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125 my ($self, $dbname) = @_;
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126 $self->{'dbname'} = $dbname if defined $dbname;
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127 return $self->{'dbname'};
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128 }
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129
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130 my %SWITCH_METHODS = map { $_ => 1 } qw/
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131 connect
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132 db_handle
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133 do
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134 prepare
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135 reconnect
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136 work_with_db_handle
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137 /;
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138
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139 sub __resolver {
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140 my ($self, $package, $method) = @_;
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141 if($self->__proxy()->can($method)) {
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142 if($SWITCH_METHODS{$method}) {
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143 return sub {
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144 my ($local_self, @args) = @_;
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145 $local_self->switch_database();
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146 return $local_self->__proxy()->$method(@args);
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147 };
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148 }
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149 else {
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150 return sub {
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151 my ($local_self, @args) = @_;
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152 return $local_self->__proxy()->$method(@args);
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153 };
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154 }
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155 }
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156 return;
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157 }
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158
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159 1;
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