includes/ExternalStoreDB.php

   1 <?php
   2 /**
   3  *
   4  * @package MediaWiki
   5  *
   6  * DB accessable external objects
   7  *
   8  */
   9 require_once( 'LoadBalancer.php' );
  10
  11
  12 /** @package MediaWiki */
  13
  14 class ExternalStoreDB {
  15         var $loadBalancers = array();
  16
  17         /**
  18          * Fetch data from given URL
  19          * @param string $url An url
  20          */
  21
  22         function &getLoadBalancer( $cluster ) {
  23                 global $wgExternalServers;
  24                 if ( !array_key_exists( $cluster, $this->loadBalancers ) ) {
  25                         $this->loadBalancers[$cluster] = LoadBalancer::newFromParams( $wgExternalServers[$cluster] );
  26                 }
  27                 return $this->loadBalancers[$cluster];
  28         }
  29
  30         function &getSlave( $cluster ) {
  31                 $lb =& $this->getLoadBalancer( $cluster );
  32                 return $lb->getConnection( DB_SLAVE );
  33         }
  34
  35         function &getMaster( $cluster ) {
  36                 $lb =& $this->getLoadBalancer( $cluster );
  37                 return $lb->getConnection( DB_MASTER );
  38         }
  39
  40         function fetchFromURL($url) {
  41                 global $wgExternalServers;
  42                 #
  43                 # URLs have the form DB://cluster/id or DB://cluster/id/itemid for concatenated storage
  44                 #
  45                 $path = explode( '/', $url );
  46                 $cluster  = $path[2];
  47                 $id       = $path[3];
  48                 if ( isset( $path[4] ) ) {
  49                         $itemID = $path[4];
  50                 } else {
  51                         $itemID = false;
  52                 }
  53
  54                 $dbr =& $this->getSlave( $cluster );
  55                 $ret = $dbr->selectField( 'blobs', 'blob_text', array( 'blob_id' => $id ) );
  56
  57                 if ( $itemID !== false ) {
  58                         # Unserialise object and get item
  59                         $obj = unserialize( $ret );
  60                         $ret = $obj->getItem( $itemID );
  61                 }
  62                 return $ret;
  63         }
  64
  65         /**
  66          * Insert a data item into a given cluster
  67          *
  68          * @param string $cluster The cluster name
  69          * @param string $data The data item
  70          * @return string URL
  71          */
  72         function store( $cluster, $data ) {
  73                 global $wgExternalServers;
  74                 $fname = 'ExternalStoreDB::store';
  75
  76                 $dbw =& $this->getMaster( $cluster );
  77
  78                 $id = $dbw->nextSequenceValue( 'blob_blob_id_seq' );
  79                 $dbw->insert( 'blobs', array( 'blob_id' => $id, 'blob_text' => $data ), $fname );
  80                 return "DB://$cluster/" . $dbw->insertId();
  81         }
  82 }
  83 ?>