Fixes #8920: Added yii\mutex\PgsqlMutex which implements mutex "lock" mechanism via PgSQL locks

framework/mutex/PgsqlMutex.php

@@ -0,0 +1,93 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yii\mutex;
+
+use Yii;
+use yii\base\InvalidConfigException;
+use yii\base\InvalidParamException;
+
+/**
+ * PgsqlMutex implements mutex "lock" mechanism via PgSQL locks.
+ *
+ * Application configuration example:
+ *
+ * ```
+ * [
+ *     'components' => [
+ *         'db' => [
+ *             'class' => 'yii\db\Connection',
+ *             'dsn' => 'pgsql:host=127.0.0.1;dbname=demo',
+ *         ]
+ *         'mutex' => [
+ *             'class' => 'yii\mutex\PgsqlMutex',
+ *         ],
+ *     ],
+ * ]
+ * ```
+ *
+ * @see Mutex
+ *
+ * @author nineinchnick <janek.jan@gmail.com>
+ * @since 2.0.5
+ */
+class PgsqlMutex extends DbMutex
+{
+    /**
+     * Initializes PgSQL specific mutex component implementation.
+     * @throws InvalidConfigException if [[db]] is not PgSQL connection.
+     */
+    public function init()
+    {
+        parent::init();
+        if ($this->db->driverName !== 'pgsql') {
+            throw new InvalidConfigException('In order to use PgsqlMutex connection must be configured to use PgSQL database.');
+        }
+    }
+
+    /**
+     * Converts a string into two 32 bit integer keys using the SHA1 hash function.
+     * @param string $name
+     * @return array contains two 32 bit integer keys
+     */
+    private function getKeysFromName($name)
+    {
+        return array_values(unpack('N2', sha1($name, true)));
+    }
+
+    /**
+     * Acquires lock by given name.
+     * @param string $name of the lock to be acquired.
+     * @param integer $timeout to wait for lock to become released.
+     * @return boolean acquiring result.
+     * @see http://www.postgresql.org/docs/9.0/static/functions-admin.html
+     */
+    protected function acquireLock($name, $timeout = 0)
+    {
+        if ($timeout !== 0) {
+            throw new InvalidParamException('PgsqlMutex does not support timeout.');
+        }
+        list($key1, $key2) = $this->getKeysFromName($name);
+        return (bool) $this->db
+            ->createCommand('SELECT pg_try_advisory_lock(:key1, :key2)', [':key1' => $key1, ':key2' => $key2])
+            ->queryScalar();
+    }
+
+    /**
+     * Releases lock by given name.
+     * @param string $name of the lock to be released.
+     * @return boolean release result.
+     * @see http://www.postgresql.org/docs/9.0/static/functions-admin.html
+     */
+    protected function releaseLock($name)
+    {
+        list($key1, $key2) = $this->getKeysFromName($name);
+        return (bool) $this->db
+            ->createCommand('SELECT pg_advisory_unlock(:key1, :key2)', [':key1' => $key1, ':key2' => $key2])
+            ->queryScalar();
+    }
+}