[FEATURE] Master/slave connection support. (#214)

* Added master/slave connection support.

* Fixed master/slave validation not checking first slave configuration.

* Refactored master/slave connection tests.

Author: Zigmas Satkevičius

src/Configuration/Connections/MasterSlaveConnection.php

@@ -0,0 +1,115 @@
+<?php
+
+namespace LaravelDoctrine\ORM\Configuration\Connections;
+
+use Doctrine\DBAL\Connections\MasterSlaveConnection as MasterSlaveDoctrineWrapper;
+use Illuminate\Contracts\Config\Repository;
+
+/**
+ * Handles master slave connection settings.
+ */
+class MasterSlaveConnection extends Connection
+{
+    /**
+     * @var array|Connection
+     */
+    private $resolvedBaseSettings;
+
+    /**
+     * @var array Ignored configuration fields for master slave configuration.
+     */
+    private $masterSlaveConfigIgnored = ['driver'];
+
+    /**
+     * MasterSlaveConnection constructor.
+     *
+     * @param Repository       $config
+     * @param array|Connection $resolvedBaseSettings
+     */
+    public function __construct(Repository $config, $resolvedBaseSettings)
+    {
+        parent::__construct($config);
+
+        $this->resolvedBaseSettings = $resolvedBaseSettings;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function resolve(array $settings = [])
+    {
+        $driver = $this->resolvedBaseSettings['driver'];
+
+        return [
+            'wrapperClass' => MasterSlaveDoctrineWrapper::class,
+            'driver'       => $driver,
+            'master'       => $this->getConnectionData(isset($settings['write']) ? $settings['write'] : [], $driver),
+            'slaves'       => $this->getSlavesConfig($settings['read'], $driver),
+        ];
+    }
+
+    /**
+     * Returns config for slave connections.
+     *
+     * @param array  $slaves
+     * @param string $driver
+     *
+     * @return array
+     */
+    public function getSlavesConfig(array $slaves, $driver)
+    {
+        $handledSlaves = [];
+        foreach ($slaves as $slave) {
+            $handledSlaves[] = $this->getConnectionData($slave, $driver);
+        }
+
+        return $handledSlaves;
+    }
+
+    /**
+     * Returns single connection (slave or master) config.
+     *
+     * @param array  $connection
+     * @param string $driver
+     *
+     * @return array
+     */
+    private function getConnectionData(array $connection, $driver)
+    {
+        $connection = $this->replaceKeyIfExists($connection, 'database', $driver === 'pdo_sqlite' ? 'path' : 'dbname');
+        $connection = $this->replaceKeyIfExists($connection, 'username', 'user');
+
+        return array_merge($this->getFilteredConfig(), $connection);
+    }
+
+    /**
+     * Returns filtered configuration to use in slaves/masters.
+     *
+     * @return array
+     */
+    private function getFilteredConfig()
+    {
+        return array_diff_key($this->resolvedBaseSettings, array_flip($this->masterSlaveConfigIgnored));
+    }
+
+    /**
+     * Replaces key in array if it exists.
+     *
+     * @param array  $array
+     * @param string $oldKey
+     * @param string $newKey
+     *
+     * @return array
+     */
+    private function replaceKeyIfExists(array $array, $oldKey, $newKey)
+    {
+        if (!isset($array[$oldKey])) {
+            return $array;
+        }
+
+        $array[$newKey] = $array[$oldKey];
+        unset($array[$oldKey]);
+
+        return $array;
+    }
+}

src/EntityManagerFactory.php

@@ -14,6 +14,7 @@
 use InvalidArgumentException;
 use LaravelDoctrine\ORM\Configuration\Cache\CacheManager;
 use LaravelDoctrine\ORM\Configuration\Connections\ConnectionManager;
+use LaravelDoctrine\ORM\Configuration\Connections\MasterSlaveConnection;
 use LaravelDoctrine\ORM\Configuration\LaravelNamingStrategy;
 use LaravelDoctrine\ORM\Configuration\MetaData\MetaData;
 use LaravelDoctrine\ORM\Configuration\MetaData\MetaDataManager;
@@ -109,6 +110,11 @@ public function create(array $settings = [])
             $driver
         );
 
+        if ($this->isMasterSlaveConfigured($driver)) {
+            $this->hasValidMasterSlaveConfig($driver);
+            $connection = (new MasterSlaveConnection($this->config, $connection))->resolve($driver);
+        }
+
         $this->setNamingStrategy($settings, $configuration);
         $this->setCustomFunctions($configuration);
         $this->setCacheSettings($configuration);
@@ -440,4 +446,40 @@ protected function registerMappingTypes(array $settings = [], EntityManagerInter
             $manager->getConnection()->getDatabasePlatform()->registerDoctrineTypeMapping($dbType, $doctrineType);
         }
     }
+
+    /**
+     * Check if master slave connection was being configured.
+     *
+     * @param array $driverConfig
+     *
+     * @return bool
+     */
+    private function isMasterSlaveConfigured(array $driverConfig)
+    {
+        // Setting read is mandatory for master/slave configuration. Setting write is optional.
+        // But if write was set and read wasn't, it means configuration is incorrect and we must inform the user.
+        return isset($driverConfig['read']) || isset($driverConfig['write']);
+    }
+
+    /**
+     * Check if slave configuration is valid.
+     *
+     * @param array $driverConfig
+     */
+    private function hasValidMasterSlaveConfig(array $driverConfig)
+    {
+        if (!isset($driverConfig['read'])) {
+            throw new \InvalidArgumentException("Parameter 'read' must be set for read/write config.");
+        }
+
+        $slaves = $driverConfig['read'];
+
+        if (!is_array($slaves) || in_array(false, array_map('is_array', $slaves))) {
+            throw new \InvalidArgumentException("Parameter 'read' must be an array containing multiple arrays.");
+        }
+
+        if (($key = array_search(0, array_map('count', $slaves))) !== false) {
+            throw new \InvalidArgumentException("Parameter 'read' config no. {$key} is empty.");
+        }
+    }
 }