Add master/slave connection code by lstrojny

lib/Doctrine/DBAL/Connections/MasterSlaveConnection.php

+<?php
+/*
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the LGPL. For more information, see
+ * <http://www.doctrine-project.org>.
+ */
+
+namespace Doctrine\DBAL\Connections;
+
+
+use Doctrine\DBAL\Connection,
+    Doctrine\DBAL\Driver,
+    Doctrine\ORM\Configuration,
+    Doctrine\Common\EventManager,
+    Doctrine\DBAL\Events;
+
+/**
+ * Master-Slave Connection
+ *
+ * Connection can be used with master-slave setups. Instantiation through the DriverManager looks like:
+ *
+ * @example
+ *
+ * $conn = DriverManager::getConnection(array(
+ *    'master' => array('driver' => 'pdo_mysql', 'user' => '', 'password' => '', 'host' => '', 'dbname' => ''),
+ *    'slaves' => array(
+ *        array('user' => 'slave1', 'password', 'host' => '', 'dbname' => ''),
+ *        array('user' => 'slave2', 'password', 'host' => '', 'dbname' => ''),
+ *    )
+ * ));
+ *
+ * You can also pass 'driverOptions' and any other documented option to each of this drivers to pass additional information.
+ *
+ * @author Lars Strojny <lstrojny@php.net>
+ * @author Benjamin Eberlei <kontakt@beberlei.de>
+ */
+class MasterSlaveConnection extends Connection
+{
+    /**
+     * Master and slave connection (one of the randomly picked slaves)
+     *
+     * @var Doctrine\DBAL\Driver\Connection[]
+     */
+    protected $connections = array('master' => null, 'slave' => null);
+
+    /**
+     * Create Master Slave Connection
+     *
+     * @param array $params
+     * @param Driver $driver
+     * @param Configuration $config
+     * @param EventManager $eventManager
+     */
+    public function __construct(array $params, Driver $driver, Configuration $config = null, EventManager $eventManager = null)
+    {
+        if ( !isset($params['slaves']) || !isset($params['master']) ) {
+            throw new \InvalidArgumentException('master or slaves configuration missing');
+        }
+        if ( count( array_filter($params['slaves'], function($v) { return !is_numeric($v); })) > 0 ) {
+            throw new \InvalidArgumentException('You have to configure multiple slaves.');
+        }
+
+        $params['master']['driver'] = $params['driver'];
+        foreach ($params['slaves'] as $slaveKey => $slave) {
+            $params['slaves'][$slaveKey]['driver'] = $params['driver'];
+        }
+
+        parent::__construct($params, $driver, $config, $eventManager);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function connect($connectionName = 'slave')
+    {
+        if ( $connectionName !== 'slave' && $connectionName !== 'master' ) {
+            throw new \InvalidArgumentException("Invalid option to connect(), only master or slave allowed.");
+        }
+
+        $forceMasterAsSlave = false;
+
+        if ($this->getTransactionNestingLevel() > 0) {
+            $connectionName = 'master';
+            $forceMasterAsSlave = true;
+        }
+
+        if ($this->connections[$connectionName]) {
+            if ($forceMasterAsSlave) {
+                $this->connections['slave'] = $this->_conn = $this->connections['master'];
+            } else {
+                $this->_conn = $this->connections[$connectionName];
+            }
+            return false;
+        }
+
+        if ($connectionName === 'master') {
+            /** Set slave connection to master to avoid invalid reads */
+            if ($this->connections['slave']) {
+                $this->connections['slave']->close();
+            }
+
+            $this->connections['master'] = $this->connections['slave'] = $this->_conn = $this->connectTo($connectionName);
+        } else {
+            $this->connections['slave'] = $this->_conn = $this->connectTo($connectionName);
+        }
+
+        if ($this->_eventManager->hasListeners(Events::postConnect)) {
+            $eventArgs = new Event\ConnectionEventArgs($this);
+            $this->_eventManager->dispatchEvent(Events::postConnect, $eventArgs);
+        }
+
+        return true;
+    }
+
+    /**
+     * Connect to a specific connection
+     *
+     * @param  string $connectionName
+     * @return Driver
+     */
+    protected function connectTo($connectionName)
+    {
+        $params = $this->getParams();
+
+        $driverOptions = isset($params['driverOptions']) ? $params['driverOptions'] : array();
+
+        $connectionParams = $this->chooseConnectionConfiguration($connectionName, $params);
+
+        $user = isset($connectionParams['user']) ? $connectionParams['user'] : null;
+        $password = isset($connectionParams['password']) ? $connectionParams['password'] : null;
+
+        return $this->_driver->connect($connectionParams, $user, $password, $driverOptions);
+    }
+
+    protected function chooseConnectionConfiguration($connectionName, $params)
+    {
+        if ($connectionName === 'master') {
+            return $params['master'];
+        }
+
+        return $params['slaves'][array_rand($params['slaves'])];
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function executeUpdate($query, array $params = array(), array $types = array())
+    {
+        $this->connect('master');
+        return parent::executeUpdate($query, $params, $types);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function beginTransaction()
+    {
+        $this->connect('master');
+        return parent::beginTransaction();
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function commit()
+    {
+        $this->connect('master');
+        return parent::commit();
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function rollback()
+    {
+        $this->connect('master');
+        return parent::rollback();
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function delete($tableName, array $identifier)
+    {
+        $this->connect('master');
+        return parent::delete($tableName, $identifier);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function update($tableName, array $data, array $identifier)
+    {
+        $this->connect('master');
+        return parent::update($tableName, $data, $identifier);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function insert($tableName, array $data)
+    {
+        $this->connect('master');
+        return parent::insert($tableName, $data);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function exec($statement)
+    {
+        $this->connect('master');
+        return parent::exec($statement);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function getWrappedConnection()
+    {
+        $this->connect('master');
+
+        return $this->_conn;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function createSavepoint($savepoint)
+    {
+        $this->connect('master');
+
+        return parent::createSavepoint($savepoint);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function releaseSavepoint($savepoint)
+    {
+        $this->connect('master');
+
+        return parent::releaseSavepoint($savepoint);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public function rollbackSavepoint($savepoint)
+    {
+        $this->connect('master');
+
+        return parent::rollbackSavepoint($savepoint);
+    }
+}