lib/dml/sqlsrv_native_moodle_recordset.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 2 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * sqlsrv specific recordset.
  19  *
  20  * @package    core_dml
  21  * @copyright  2009 onwards Eloy Lafuente (stronk7) {@link http://stronk7.com}
  22  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v2 or later
  23  */
  24
  25 defined('MOODLE_INTERNAL') || die();
  26
  27 require_once(__DIR__.'/moodle_recordset.php');
  28
  29 class sqlsrv_native_moodle_recordset extends moodle_recordset {
  30
  31     protected $rsrc;
  32     protected $current;
  33
  34     /** @var array recordset buffer */
  35     protected $buffer = null;
  36
  37     /** @var sqlsrv_native_moodle_database */
  38     protected $db;
  39
  40     public function __construct($rsrc, sqlsrv_native_moodle_database $db) {
  41         $this->rsrc    = $rsrc;
  42         $this->current = $this->fetch_next();
  43         $this->db      = $db;
  44     }
  45
  46     /**
  47      * Inform existing open recordsets that transaction
  48      * is starting, this works around MARS problem described
  49      * in MDL-37734.
  50      */
  51     public function transaction_starts() {
  52         if ($this->buffer !== null) {
  53             $this->unregister();
  54             return;
  55         }
  56         if (!$this->rsrc) {
  57             $this->unregister();
  58             return;
  59         }
  60         // This might eat memory pretty quickly...
  61         raise_memory_limit('2G');
  62         $this->buffer = array();
  63
  64         while($next = $this->fetch_next()) {
  65             $this->buffer[] = $next;
  66         }
  67     }
  68
  69     /**
  70      * Unregister recordset from the global list of open recordsets.
  71      */
  72     private function unregister() {
  73         if ($this->db) {
  74             $this->db->recordset_closed($this);
  75             $this->db = null;
  76         }
  77     }
  78
  79     public function __destruct() {
  80         $this->close();
  81     }
  82
  83     private function fetch_next() {
  84         if (!$this->rsrc) {
  85             return false;
  86         }
  87         if (!$row = sqlsrv_fetch_array($this->rsrc, SQLSRV_FETCH_ASSOC)) {
  88             sqlsrv_free_stmt($this->rsrc);
  89             $this->rsrc = null;
  90             $this->unregister();
  91             return false;
  92         }
  93
  94         unset($row['sqlsrvrownumber']);
  95         $row = array_change_key_case($row, CASE_LOWER);
  96         return $row;
  97     }
  98
  99     public function current() {
 100         return (object)$this->current;
 101     }
 102
 103     public function key() {
 104         // return first column value as key
 105         if (!$this->current) {
 106             return false;
 107         }
 108         $key = reset($this->current);
 109         return $key;
 110     }
 111
 112     public function next() {
 113         if ($this->buffer === null) {
 114             $this->current = $this->fetch_next();
 115         } else {
 116             $this->current = array_shift($this->buffer);
 117         }
 118     }
 119
 120     public function valid() {
 121         return !empty($this->current);
 122     }
 123
 124     public function close() {
 125         if ($this->rsrc) {
 126             sqlsrv_free_stmt($this->rsrc);
 127             $this->rsrc  = null;
 128         }
 129         $this->current = null;
 130         $this->buffer  = null;
 131         $this->unregister();
 132     }
 133 }