first commit

9 files changed, 843 insertions, 0 deletions

diff --git a/www/wiki/includes/config/Config.php b/www/wiki/includes/config/Config.php
new file mode 100644
index 00000000..38f589dc
--- /dev/null
+++ b/www/wiki/includes/config/Config.php
@@ -0,0 +1,47 @@
+<?php
+/**
+ * Copyright 2014
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Interface for configuration instances
+ *
+ * @since 1.23
+ */
+interface Config {
+
+	/**
+	 * Get a configuration variable such as "Sitename" or "UploadMaintenance."
+	 *
+	 * @param string $name Name of configuration option
+	 * @return mixed Value configured
+	 * @throws ConfigException
+	 */
+	public function get( $name );
+
+	/**
+	 * Check whether a configuration option is set for the given name
+	 *
+	 * @param string $name Name of configuration option
+	 * @return bool
+	 * @since 1.24
+	 */
+	public function has( $name );
+}
diff --git a/www/wiki/includes/config/ConfigException.php b/www/wiki/includes/config/ConfigException.php
new file mode 100644
index 00000000..3b3ba9de
--- /dev/null
+++ b/www/wiki/includes/config/ConfigException.php
@@ -0,0 +1,29 @@
+<?php
+/**
+ * Copyright 2014
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Exceptions for config failures
+ *
+ * @since 1.23
+ */
+class ConfigException extends Exception {
+}
diff --git a/www/wiki/includes/config/ConfigFactory.php b/www/wiki/includes/config/ConfigFactory.php
new file mode 100644
index 00000000..2c7afdae
--- /dev/null
+++ b/www/wiki/includes/config/ConfigFactory.php
@@ -0,0 +1,155 @@
+<?php
+
+/**
+ * Copyright 2014
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+use MediaWiki\Services\SalvageableService;
+use Wikimedia\Assert\Assert;
+
+/**
+ * Factory class to create Config objects
+ *
+ * @since 1.23
+ */
+class ConfigFactory implements SalvageableService {
+
+	/**
+	 * Map of config name => callback
+	 * @var array
+	 */
+	protected $factoryFunctions = [];
+
+	/**
+	 * Config objects that have already been created
+	 * name => Config object
+	 * @var array
+	 */
+	protected $configs = [];
+
+	/**
+	 * @deprecated since 1.27, use MediaWikiServices::getConfigFactory() instead.
+	 *
+	 * @return ConfigFactory
+	 */
+	public static function getDefaultInstance() {
+		return \MediaWiki\MediaWikiServices::getInstance()->getConfigFactory();
+	}
+
+	/**
+	 * Re-uses existing Cache objects from $other. Cache objects are only re-used if the
+	 * registered factory function for both is the same. Cache config is not copied,
+	 * and only instances of caches defined on this instance with the same config
+	 * are copied.
+	 *
+	 * @see SalvageableService::salvage()
+	 *
+	 * @param SalvageableService $other The object to salvage state from. $other must have the
+	 * exact same type as $this.
+	 */
+	public function salvage( SalvageableService $other ) {
+		Assert::parameterType( self::class, $other, '$other' );
+
+		/** @var ConfigFactory $other */
+		foreach ( $other->factoryFunctions as $name => $otherFunc ) {
+			if ( !isset( $this->factoryFunctions[$name] ) ) {
+				continue;
+			}
+
+			// if the callback function is the same, salvage the Cache object
+			// XXX: Closures are never equal!
+			if ( isset( $other->configs[$name] )
+				&& $this->factoryFunctions[$name] == $otherFunc
+			) {
+				$this->configs[$name] = $other->configs[$name];
+				unset( $other->configs[$name] );
+			}
+		}
+
+		// disable $other
+		$other->factoryFunctions = [];
+		$other->configs = [];
+	}
+
+	/**
+	 * @return string[]
+	 */
+	public function getConfigNames() {
+		return array_keys( $this->factoryFunctions );
+	}
+
+	/**
+	 * Register a new config factory function.
+	 * Will override if it's already registered.
+	 * Use "*" for $name to provide a fallback config for all unknown names.
+	 * @param string $name
+	 * @param callable|Config $callback A factory callback that takes this ConfigFactory
+	 *        as an argument and returns a Config instance, or an existing Config instance.
+	 * @throws InvalidArgumentException If an invalid callback is provided
+	 */
+	public function register( $name, $callback ) {
+		if ( !is_callable( $callback ) && !( $callback instanceof Config ) ) {
+			if ( is_array( $callback ) ) {
+				$callback = '[ ' . implode( ', ', $callback ) . ' ]';
+			} elseif ( is_object( $callback ) ) {
+				$callback = 'instanceof ' . get_class( $callback );
+			}
+			throw new InvalidArgumentException( 'Invalid callback \'' . $callback . '\' provided' );
+		}
+
+		unset( $this->configs[$name] );
+		$this->factoryFunctions[$name] = $callback;
+	}
+
+	/**
+	 * Create a given Config using the registered callback for $name.
+	 * If an object was already created, the same Config object is returned.
+	 * @param string $name Name of the extension/component you want a Config object for
+	 *                     'main' is used for core
+	 * @throws ConfigException If a factory function isn't registered for $name
+	 * @throws UnexpectedValueException If the factory function returns a non-Config object
+	 * @return Config
+	 */
+	public function makeConfig( $name ) {
+		if ( !isset( $this->configs[$name] ) ) {
+			$key = $name;
+			if ( !isset( $this->factoryFunctions[$key] ) ) {
+				$key = '*';
+			}
+			if ( !isset( $this->factoryFunctions[$key] ) ) {
+				throw new ConfigException( "No registered builder available for $name." );
+			}
+
+			if ( $this->factoryFunctions[$key] instanceof Config ) {
+				$conf = $this->factoryFunctions[$key];
+			} else {
+				$conf = call_user_func( $this->factoryFunctions[$key], $this );
+			}
+
+			if ( $conf instanceof Config ) {
+				$this->configs[$name] = $conf;
+			} else {
+				throw new UnexpectedValueException( "The builder for $name returned a non-Config object." );
+			}
+		}
+
+		return $this->configs[$name];
+	}
+
+}
diff --git a/www/wiki/includes/config/EtcdConfig.php b/www/wiki/includes/config/EtcdConfig.php
new file mode 100644
index 00000000..7020159f
--- /dev/null
+++ b/www/wiki/includes/config/EtcdConfig.php
@@ -0,0 +1,333 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+use Psr\Log\LoggerAwareInterface;
+use Psr\Log\LoggerInterface;
+use Wikimedia\ObjectFactory;
+use Wikimedia\WaitConditionLoop;
+
+/**
+ * Interface for configuration instances
+ *
+ * @since 1.29
+ */
+class EtcdConfig implements Config, LoggerAwareInterface {
+	/** @var MultiHttpClient */
+	private $http;
+	/** @var BagOStuff */
+	private $srvCache;
+	/** @var array */
+	private $procCache;
+	/** @var LoggerInterface */
+	private $logger;
+
+	/** @var string */
+	private $host;
+	/** @var string */
+	private $protocol;
+	/** @var string */
+	private $directory;
+	/** @var string */
+	private $encoding;
+	/** @var int */
+	private $baseCacheTTL;
+	/** @var int */
+	private $skewCacheTTL;
+	/** @var int */
+	private $timeout;
+
+	/**
+	 * @param array $params Parameter map:
+	 *   - host: the host address and port
+	 *   - protocol: either http or https
+	 *   - directory: the etc "directory" were MediaWiki specific variables are located
+	 *   - encoding: one of ("JSON", "YAML"). Defaults to JSON. [optional]
+	 *   - cache: BagOStuff instance or ObjectFactory spec thereof for a server cache.
+	 *            The cache will also be used as a fallback if etcd is down. [optional]
+	 *   - cacheTTL: logical cache TTL in seconds [optional]
+	 *   - skewTTL: maximum seconds to randomly lower the assigned TTL on cache save [optional]
+	 *   - timeout: seconds to wait for etcd before throwing an error [optional]
+	 */
+	public function __construct( array $params ) {
+		$params += [
+			'protocol' => 'http',
+			'encoding' => 'JSON',
+			'cacheTTL' => 10,
+			'skewTTL' => 1,
+			'timeout' => 2
+		];
+
+		$this->host = $params['host'];
+		$this->protocol = $params['protocol'];
+		$this->directory = trim( $params['directory'], '/' );
+		$this->encoding = $params['encoding'];
+		$this->skewCacheTTL = $params['skewTTL'];
+		$this->baseCacheTTL = max( $params['cacheTTL'] - $this->skewCacheTTL, 0 );
+		$this->timeout = $params['timeout'];
+
+		if ( !isset( $params['cache'] ) ) {
+			$this->srvCache = new HashBagOStuff();
+		} elseif ( $params['cache'] instanceof BagOStuff ) {
+			$this->srvCache = $params['cache'];
+		} else {
+			$this->srvCache = ObjectFactory::getObjectFromSpec( $params['cache'] );
+		}
+
+		$this->logger = new Psr\Log\NullLogger();
+		$this->http = new MultiHttpClient( [
+			'connTimeout' => $this->timeout,
+			'reqTimeout' => $this->timeout,
+			'logger' => $this->logger
+		] );
+	}
+
+	public function setLogger( LoggerInterface $logger ) {
+		$this->logger = $logger;
+		$this->http->setLogger( $logger );
+	}
+
+	public function has( $name ) {
+		$this->load();
+
+		return array_key_exists( $name, $this->procCache['config'] );
+	}
+
+	public function get( $name ) {
+		$this->load();
+
+		if ( !array_key_exists( $name, $this->procCache['config'] ) ) {
+			throw new ConfigException( "No entry found for '$name'." );
+		}
+
+		return $this->procCache['config'][$name];
+	}
+
+	public function getModifiedIndex() {
+		$this->load();
+		return $this->procCache['modifiedIndex'];
+	}
+
+	/**
+	 * @throws ConfigException
+	 */
+	private function load() {
+		if ( $this->procCache !== null ) {
+			return; // already loaded
+		}
+
+		$now = microtime( true );
+		$key = $this->srvCache->makeGlobalKey(
+			__CLASS__,
+			$this->host,
+			$this->directory
+		);
+
+		// Get the cached value or block until it is regenerated (by this or another thread)...
+		$data = null; // latest config info
+		$error = null; // last error message
+		$loop = new WaitConditionLoop(
+			function () use ( $key, $now, &$data, &$error ) {
+				// Check if the values are in cache yet...
+				$data = $this->srvCache->get( $key );
+				if ( is_array( $data ) && $data['expires'] > $now ) {
+					$this->logger->debug( "Found up-to-date etcd configuration cache." );
+
+					return WaitConditionLoop::CONDITION_REACHED;
+				}
+
+				// Cache is either empty or stale;
+				// refresh the cache from etcd, using a mutex to reduce stampedes...
+				if ( $this->srvCache->lock( $key, 0, $this->baseCacheTTL ) ) {
+					try {
+						$etcdResponse = $this->fetchAllFromEtcd();
+						$error = $etcdResponse['error'];
+						if ( is_array( $etcdResponse['config'] ) ) {
+							// Avoid having all servers expire cache keys at the same time
+							$expiry = microtime( true ) + $this->baseCacheTTL;
+							$expiry += mt_rand( 0, 1e6 ) / 1e6 * $this->skewCacheTTL;
+							$data = [
+								'config' => $etcdResponse['config'],
+								'expires' => $expiry,
+								'modifiedIndex' => $etcdResponse['modifiedIndex']
+							];
+							$this->srvCache->set( $key, $data, BagOStuff::TTL_INDEFINITE );
+
+							$this->logger->info( "Refreshed stale etcd configuration cache." );
+
+							return WaitConditionLoop::CONDITION_REACHED;
+						} else {
+							$this->logger->error( "Failed to fetch configuration: $error" );
+							if ( !$etcdResponse['retry'] ) {
+								// Fail fast since the error is likely to keep happening
+								return WaitConditionLoop::CONDITION_FAILED;
+							}
+						}
+					} finally {
+						$this->srvCache->unlock( $key ); // release mutex
+					}
+				}
+
+				if ( is_array( $data ) ) {
+					$this->logger->info( "Using stale etcd configuration cache." );
+
+					return WaitConditionLoop::CONDITION_REACHED;
+				}
+
+				return WaitConditionLoop::CONDITION_CONTINUE;
+			},
+			$this->timeout
+		);
+
+		if ( $loop->invoke() !== WaitConditionLoop::CONDITION_REACHED ) {
+			// No cached value exists and etcd query failed; throw an error
+			throw new ConfigException( "Failed to load configuration from etcd: $error" );
+		}
+
+		$this->procCache = $data;
+	}
+
+	/**
+	 * @return array (containing the keys config, error, retry, modifiedIndex)
+	 */
+	public function fetchAllFromEtcd() {
+		// TODO: inject DnsSrvDiscoverer in order to be able to test this method
+		$dsd = new DnsSrvDiscoverer( $this->host );
+		$servers = $dsd->getServers();
+		if ( !$servers ) {
+			return $this->fetchAllFromEtcdServer( $this->host );
+		}
+
+		do {
+			// Pick a random etcd server from dns
+			$server = $dsd->pickServer( $servers );
+			$host = IP::combineHostAndPort( $server['target'], $server['port'] );
+			// Try to load the config from this particular server
+			$response = $this->fetchAllFromEtcdServer( $host );
+			if ( is_array( $response['config'] ) || $response['retry'] ) {
+				break;
+			}
+
+			// Avoid the server next time if that failed
+			$servers = $dsd->removeServer( $server, $servers );
+		} while ( $servers );
+
+		return $response;
+	}
+
+	/**
+	 * @param string $address Host and port
+	 * @return array (containing the keys config, error, retry, modifiedIndex)
+	 */
+	protected function fetchAllFromEtcdServer( $address ) {
+		// Retrieve all the values under the MediaWiki config directory
+		list( $rcode, $rdesc, /* $rhdrs */, $rbody, $rerr ) = $this->http->run( [
+			'method' => 'GET',
+			'url' => "{$this->protocol}://{$address}/v2/keys/{$this->directory}/?recursive=true",
+			'headers' => [ 'content-type' => 'application/json' ]
+		] );
+
+		$response = [ 'config' => null, 'error' => null, 'retry' => false, 'modifiedIndex' => 0 ];
+
+		static $terminalCodes = [ 404 => true ];
+		if ( $rcode < 200 || $rcode > 399 ) {
+			$response['error'] = strlen( $rerr ) ? $rerr : "HTTP $rcode ($rdesc)";
+			$response['retry'] = empty( $terminalCodes[$rcode] );
+			return $response;
+		}
+
+		try {
+			$parsedResponse = $this->parseResponse( $rbody );
+		} catch ( EtcdConfigParseError $e ) {
+			$parsedResponse = [ 'error' => $e->getMessage() ];
+		}
+		return array_merge( $response, $parsedResponse );
+	}
+
+	/**
+	 * Parse a response body, throwing EtcdConfigParseError if there is a validation error
+	 *
+	 * @param string $rbody
+	 * @return array
+	 */
+	protected function parseResponse( $rbody ) {
+		$info = json_decode( $rbody, true );
+		if ( $info === null ) {
+			throw new EtcdConfigParseError( "Error unserializing JSON response." );
+		}
+		if ( !isset( $info['node'] ) || !is_array( $info['node'] ) ) {
+			throw new EtcdConfigParseError(
+				"Unexpected JSON response: Missing or invalid node at top level." );
+		}
+		$config = [];
+		$lastModifiedIndex = $this->parseDirectory( '', $info['node'], $config );
+		return [ 'modifiedIndex' => $lastModifiedIndex, 'config' => $config ];
+	}
+
+	/**
+	 * Recursively parse a directory node and populate the array passed by
+	 * reference, throwing EtcdConfigParseError if there is a validation error
+	 *
+	 * @param string $dirName The relative directory name
+	 * @param array $dirNode The decoded directory node
+	 * @param array &$config The output array
+	 * @return int lastModifiedIndex The maximum last modified index across all keys in the directory
+	 */
+	protected function parseDirectory( $dirName, $dirNode, &$config ) {
+		$lastModifiedIndex = 0;
+		if ( !isset( $dirNode['nodes'] ) ) {
+			throw new EtcdConfigParseError(
+				"Unexpected JSON response in dir '$dirName'; missing 'nodes' list." );
+		}
+		if ( !is_array( $dirNode['nodes'] ) ) {
+			throw new EtcdConfigParseError(
+				"Unexpected JSON response in dir '$dirName'; 'nodes' is not an array." );
+		}
+
+		foreach ( $dirNode['nodes'] as $node ) {
+			$baseName = basename( $node['key'] );
+			$fullName = $dirName === '' ? $baseName : "$dirName/$baseName";
+			if ( !empty( $node['dir'] ) ) {
+				$lastModifiedIndex = max(
+					$this->parseDirectory( $fullName, $node, $config ),
+					$lastModifiedIndex );
+			} else {
+				$value = $this->unserialize( $node['value'] );
+				if ( !is_array( $value ) || !array_key_exists( 'val', $value ) ) {
+					throw new EtcdConfigParseError( "Failed to parse value for '$fullName'." );
+				}
+				$lastModifiedIndex = max( $node['modifiedIndex'], $lastModifiedIndex );
+				$config[$fullName] = $value['val'];
+			}
+		}
+		return $lastModifiedIndex;
+	}
+
+	/**
+	 * @param string $string
+	 * @return mixed
+	 */
+	private function unserialize( $string ) {
+		if ( $this->encoding === 'YAML' ) {
+			return yaml_parse( $string );
+		} else { // JSON
+			return json_decode( $string, true );
+		}
+	}
+}
diff --git a/www/wiki/includes/config/EtcdConfigParseError.php b/www/wiki/includes/config/EtcdConfigParseError.php
new file mode 100644
index 00000000..cab90a8e
--- /dev/null
+++ b/www/wiki/includes/config/EtcdConfigParseError.php
@@ -0,0 +1,4 @@
+<?php
+
+class EtcdConfigParseError extends Exception {
+}
diff --git a/www/wiki/includes/config/GlobalVarConfig.php b/www/wiki/includes/config/GlobalVarConfig.php
new file mode 100644
index 00000000..62953719
--- /dev/null
+++ b/www/wiki/includes/config/GlobalVarConfig.php
@@ -0,0 +1,87 @@
+<?php
+/**
+ * Copyright 2014
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Accesses configuration settings from $GLOBALS
+ *
+ * @since 1.23
+ */
+class GlobalVarConfig implements Config {
+
+	/**
+	 * Prefix to use for configuration variables
+	 * @var string
+	 */
+	private $prefix;
+
+	/**
+	 * Default builder function
+	 * @return GlobalVarConfig
+	 */
+	public static function newInstance() {
+		return new GlobalVarConfig();
+	}
+
+	public function __construct( $prefix = 'wg' ) {
+		$this->prefix = $prefix;
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public function get( $name ) {
+		if ( !$this->has( $name ) ) {
+			throw new ConfigException( __METHOD__ . ": undefined option: '$name'" );
+		}
+		return $this->getWithPrefix( $this->prefix, $name );
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public function has( $name ) {
+		return $this->hasWithPrefix( $this->prefix, $name );
+	}
+
+	/**
+	 * Get a variable with a given prefix, if not the defaults.
+	 *
+	 * @param string $prefix Prefix to use on the variable, if one.
+	 * @param string $name Variable name without prefix
+	 * @return mixed
+	 */
+	protected function getWithPrefix( $prefix, $name ) {
+		return $GLOBALS[$prefix . $name];
+	}
+
+	/**
+	 * Check if a variable with a given prefix is set
+	 *
+	 * @param string $prefix Prefix to use on the variable
+	 * @param string $name Variable name without prefix
+	 * @return bool
+	 */
+	protected function hasWithPrefix( $prefix, $name ) {
+		$var = $prefix . $name;
+		return array_key_exists( $var, $GLOBALS );
+	}
+}
diff --git a/www/wiki/includes/config/HashConfig.php b/www/wiki/includes/config/HashConfig.php
new file mode 100644
index 00000000..d020d20f
--- /dev/null
+++ b/www/wiki/includes/config/HashConfig.php
@@ -0,0 +1,78 @@
+<?php
+/**
+ * Copyright 2014
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * A Config instance which stores all settings as a member variable
+ *
+ * @since 1.24
+ */
+class HashConfig implements Config, MutableConfig {
+
+	/**
+	 * Array of config settings
+	 *
+	 * @var array
+	 */
+	private $settings;
+
+	/**
+	 * @return HashConfig
+	 */
+	public static function newInstance() {
+		return new HashConfig;
+	}
+
+	/**
+	 * @param array $settings Any current settings to pre-load
+	 */
+	public function __construct( array $settings = [] ) {
+		$this->settings = $settings;
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public function get( $name ) {
+		if ( !$this->has( $name ) ) {
+			throw new ConfigException( __METHOD__ . ": undefined option: '$name'" );
+		}
+
+		return $this->settings[$name];
+	}
+
+	/**
+	 * @inheritDoc
+	 * @since 1.24
+	 */
+	public function has( $name ) {
+		return array_key_exists( $name, $this->settings );
+	}
+
+	/**
+	 * @see MutableConfig::set
+	 * @param string $name
+	 * @param mixed $value
+	 */
+	public function set( $name, $value ) {
+		$this->settings[$name] = $value;
+	}
+}
diff --git a/www/wiki/includes/config/MultiConfig.php b/www/wiki/includes/config/MultiConfig.php
new file mode 100644
index 00000000..2bbc84c9
--- /dev/null
+++ b/www/wiki/includes/config/MultiConfig.php
@@ -0,0 +1,72 @@
+<?php
+/**
+ * Copyright 2014
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Provides a fallback sequence for Config objects
+ *
+ * @since 1.24
+ */
+class MultiConfig implements Config {
+
+	/**
+	 * Array of Config objects to use
+	 * Order matters, the Config objects
+	 * will be checked in order to see
+	 * whether they have the requested setting
+	 *
+	 * @var Config[]
+	 */
+	private $configs;
+
+	/**
+	 * @param Config[] $configs
+	 */
+	public function __construct( array $configs ) {
+		$this->configs = $configs;
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public function get( $name ) {
+		foreach ( $this->configs as $config ) {
+			if ( $config->has( $name ) ) {
+				return $config->get( $name );
+			}
+		}
+
+		throw new ConfigException( __METHOD__ . ": undefined option: '$name'" );
+	}
+
+	/**
+	 * @inheritDoc
+	 */
+	public function has( $name ) {
+		foreach ( $this->configs as $config ) {
+			if ( $config->has( $name ) ) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+}
diff --git a/www/wiki/includes/config/MutableConfig.php b/www/wiki/includes/config/MutableConfig.php
new file mode 100644
index 00000000..e765e3bc
--- /dev/null
+++ b/www/wiki/includes/config/MutableConfig.php
@@ -0,0 +1,38 @@
+<?php
+/**
+ * Copyright 2014
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * Interface for mutable configuration instances
+ *
+ * @since 1.24
+ */
+interface MutableConfig {
+
+	/**
+	 * Set a configuration variable such a "Sitename" to something like "My Wiki"
+	 *
+	 * @param string $name Name of configuration option
+	 * @param mixed $value Value to set
+	 * @throws ConfigException
+	 */
+	public function set( $name, $value );
+}