add identity and lock

[m6w6/pq-gateway] / lib / pq / Gateway / Table / PessimisticLock.php

diff --git a/lib/pq/Gateway/Table/PessimisticLock.php b/lib/pq/Gateway/Table/PessimisticLock.php
new file mode 100644 (file)
index 0000000..e711b46
--- /dev/null
+++ b/lib/pq/Gateway/Table/PessimisticLock.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace pq\Gateway\Table;
+
+use \pq\Gateway\Row;
+
+/**
+ * A pessimistic row lock implementation using an additional SELECT FOR UPDATE
+ */
+class PessimisticLock implements LockInterface
+{
+       /**
+        * @inheritdoc
+        * @param \pq\Gateway\Row $row
+        * @param array $ignore
+        * @throws \UnexpectedValueException if the row has already been modified
+        */
+       function criteria(Row $row, array &$ignore) {
+               $where = array();
+               foreach ($row->getIdentity() as $col => $val) {
+                       if (isset($val)) {
+                               $where["$col="] = $val;
+                       } else {
+                               $where["$col IS"] = new QueryExpr("NULL");
+                       }
+               }
+               
+               if (1 != count($rowset = $row->getTable()->find($where, null, 0, 0, "update nowait"))) {
+                       throw new \UnexpectedValueException("Failed to select a single row");
+               }
+               if ($rowset->current()->getData() != $row->getData()) {
+                       throw new \UnexpectedValueException("Row has already been modified");
+               }
+       }
+}
\ No newline at end of file