git.m6w6.name Git - m6w6/pq-gateway/blob - lib/pq/Gateway/Table/PessimisticLock.php

   1 <?php
   2
   3 namespace pq\Gateway\Table;
   4
   5 use \pq\Gateway\Row;
   6
   7 /**
   8  * A pessimistic row lock implementation using an additional SELECT FOR UPDATE
   9  */
  10 class PessimisticLock implements \SplObserver
  11 {
  12         /**
  13          * @param \pq\Gateway\Table $table
  14          * @param \pq\Gateway\Row $row
  15          * @param string $event create/update/delete
  16          * @param array $where reference to the criteria
  17          * @throws \UnexpectedValueException if the row has already been modified
  18          */
  19         function update(\SplSubject $table, Row $row = null, $event = null, array &$where = null) {
  20                 if ($event === "update") {
  21                         if (1 != count($rowset = $table->find($where, null, 0, 0, "update nowait"))) {
  22                                 throw new \UnexpectedValueException("Failed to select a single row");
  23                         }
  24                         if ($rowset->current()->getData() != $row->getData()) {
  25                                 throw new \UnexpectedValueException("Row has already been modified");
  26                         }
  27                 }
  28         }
  29 }