first commit

8 files changed, 697 insertions, 0 deletions

diff --git a/www/wiki/includes/services/CannotReplaceActiveServiceException.php b/www/wiki/includes/services/CannotReplaceActiveServiceException.php
new file mode 100644
index 00000000..49930737
--- /dev/null
+++ b/www/wiki/includes/services/CannotReplaceActiveServiceException.php
@@ -0,0 +1,43 @@
+<?php
+namespace MediaWiki\Services;
+
+use Exception;
+use RuntimeException;
+
+/**
+ * Exception thrown when trying to replace an already active service.
+ *
+ * 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
+ *
+ * @since 1.27
+ */
+
+/**
+ * Exception thrown when trying to replace an already active service.
+ */
+class CannotReplaceActiveServiceException extends RuntimeException {
+
+	/**
+	 * @param string $serviceName
+	 * @param Exception|null $previous
+	 */
+	public function __construct( $serviceName, Exception $previous = null ) {
+		parent::__construct( "Cannot replace an active service: $serviceName", 0, $previous );
+	}
+
+}
diff --git a/www/wiki/includes/services/ContainerDisabledException.php b/www/wiki/includes/services/ContainerDisabledException.php
new file mode 100644
index 00000000..ede076d9
--- /dev/null
+++ b/www/wiki/includes/services/ContainerDisabledException.php
@@ -0,0 +1,42 @@
+<?php
+namespace MediaWiki\Services;
+
+use Exception;
+use RuntimeException;
+
+/**
+ * Exception thrown when trying to access a service on a disabled container or factory.
+ *
+ * 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
+ *
+ * @since 1.27
+ */
+
+/**
+ * Exception thrown when trying to access a service on a disabled container or factory.
+ */
+class ContainerDisabledException extends RuntimeException {
+
+	/**
+	 * @param Exception|null $previous
+	 */
+	public function __construct( Exception $previous = null ) {
+		parent::__construct( 'Container disabled!', 0, $previous );
+	}
+
+}
diff --git a/www/wiki/includes/services/DestructibleService.php b/www/wiki/includes/services/DestructibleService.php
new file mode 100644
index 00000000..6ce9af2a
--- /dev/null
+++ b/www/wiki/includes/services/DestructibleService.php
@@ -0,0 +1,45 @@
+<?php
+namespace MediaWiki\Services;
+
+/**
+ * Interface for destructible services.
+ *
+ * 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
+ *
+ * @since 1.27
+ */
+
+/**
+ * DestructibleService defines a standard interface for shutting down a service instance.
+ * The intended use is for a service container to be able to shut down services that should
+ * no longer be used, and allow such services to release any system resources.
+ *
+ * @note There is no expectation that services will be destroyed when the process (or web request)
+ * terminates.
+ */
+interface DestructibleService {
+
+	/**
+	 * Notifies the service object that it should expect to no longer be used, and should release
+	 * any system resources it may own. The behavior of all service methods becomes undefined after
+	 * destroy() has been called. It is recommended that implementing classes should throw an
+	 * exception when service methods are accessed after destroy() has been called.
+	 */
+	public function destroy();
+
+}
diff --git a/www/wiki/includes/services/NoSuchServiceException.php b/www/wiki/includes/services/NoSuchServiceException.php
new file mode 100644
index 00000000..36e50d2f
--- /dev/null
+++ b/www/wiki/includes/services/NoSuchServiceException.php
@@ -0,0 +1,43 @@
+<?php
+namespace MediaWiki\Services;
+
+use Exception;
+use RuntimeException;
+
+/**
+ * Exception thrown when the requested service is not known.
+ *
+ * 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
+ *
+ * @since 1.27
+ */
+
+/**
+ * Exception thrown when the requested service is not known.
+ */
+class NoSuchServiceException extends RuntimeException {
+
+	/**
+	 * @param string $serviceName
+	 * @param Exception|null $previous
+	 */
+	public function __construct( $serviceName, Exception $previous = null ) {
+		parent::__construct( "No such service: $serviceName", 0, $previous );
+	}
+
+}
diff --git a/www/wiki/includes/services/SalvageableService.php b/www/wiki/includes/services/SalvageableService.php
new file mode 100644
index 00000000..a613050d
--- /dev/null
+++ b/www/wiki/includes/services/SalvageableService.php
@@ -0,0 +1,58 @@
+<?php
+namespace MediaWiki\Services;
+
+/**
+ * Interface for salvageable services.
+ *
+ * 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
+ *
+ * @since 1.28
+ */
+
+/**
+ * SalvageableService defines an interface for services that are able to salvage state from a
+ * previous instance of the same class. The intent is to allow new service instances to re-use
+ * resources that would be expensive to re-create, such as cached data or network connections.
+ *
+ * @note There is no expectation that services will be destroyed when the process (or web request)
+ * terminates.
+ */
+interface SalvageableService {
+
+	/**
+	 * Re-uses state from $other. $other must not be used after being passed to salvage(),
+	 * and should be considered to be destroyed.
+	 *
+	 * @note Implementations are responsible for determining what parts of $other can be re-used
+	 * safely. In particular, implementations should check that the relevant configuration of
+	 * $other is the same as in $this before re-using resources from $other.
+	 *
+	 * @note Implementations must take care to detach any re-used resources from the original
+	 * service instance. If $other is destroyed later, resources that are now used by the
+	 * new service instance must not be affected.
+	 *
+	 * @note If $other is a DestructibleService, implementations should make sure that $other
+	 * is in destroyed state after salvage finished. This may be done by calling $other->destroy()
+	 * after carefully detaching all relevant resources.
+	 *
+	 * @param SalvageableService $other The object to salvage state from. $other must have the
+	 * exact same type as $this.
+	 */
+	public function salvage( SalvageableService $other );
+
+}
diff --git a/www/wiki/includes/services/ServiceAlreadyDefinedException.php b/www/wiki/includes/services/ServiceAlreadyDefinedException.php
new file mode 100644
index 00000000..c6344d39
--- /dev/null
+++ b/www/wiki/includes/services/ServiceAlreadyDefinedException.php
@@ -0,0 +1,45 @@
+<?php
+namespace MediaWiki\Services;
+
+use Exception;
+use RuntimeException;
+
+/**
+ * Exception thrown when a service was already defined, but the
+ * caller expected it to not exist.
+ *
+ * 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
+ *
+ * @since 1.27
+ */
+
+/**
+ * Exception thrown when a service was already defined, but the
+ * caller expected it to not exist.
+ */
+class ServiceAlreadyDefinedException extends RuntimeException {
+
+	/**
+	 * @param string $serviceName
+	 * @param Exception|null $previous
+	 */
+	public function __construct( $serviceName, Exception $previous = null ) {
+		parent::__construct( "Service already defined: $serviceName", 0, $previous );
+	}
+
+}
diff --git a/www/wiki/includes/services/ServiceContainer.php b/www/wiki/includes/services/ServiceContainer.php
new file mode 100644
index 00000000..9f09e22f
--- /dev/null
+++ b/www/wiki/includes/services/ServiceContainer.php
@@ -0,0 +1,378 @@
+<?php
+namespace MediaWiki\Services;
+
+use InvalidArgumentException;
+use RuntimeException;
+use Wikimedia\Assert\Assert;
+
+/**
+ * Generic service container.
+ *
+ * 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
+ *
+ * @since 1.27
+ */
+
+/**
+ * ServiceContainer provides a generic service to manage named services using
+ * lazy instantiation based on instantiator callback functions.
+ *
+ * Services managed by an instance of ServiceContainer may or may not implement
+ * a common interface.
+ *
+ * @note When using ServiceContainer to manage a set of services, consider
+ * creating a wrapper or a subclass that provides access to the services via
+ * getter methods with more meaningful names and more specific return type
+ * declarations.
+ *
+ * @see docs/injection.txt for an overview of using dependency injection in the
+ *      MediaWiki code base.
+ */
+class ServiceContainer implements DestructibleService {
+
+	/**
+	 * @var object[]
+	 */
+	private $services = [];
+
+	/**
+	 * @var callable[]
+	 */
+	private $serviceInstantiators = [];
+
+	/**
+	 * @var bool[] disabled status, per service name
+	 */
+	private $disabled = [];
+
+	/**
+	 * @var array
+	 */
+	private $extraInstantiationParams;
+
+	/**
+	 * @var bool
+	 */
+	private $destroyed = false;
+
+	/**
+	 * @param array $extraInstantiationParams Any additional parameters to be passed to the
+	 * instantiator function when creating a service. This is typically used to provide
+	 * access to additional ServiceContainers or Config objects.
+	 */
+	public function __construct( array $extraInstantiationParams = [] ) {
+		$this->extraInstantiationParams = $extraInstantiationParams;
+	}
+
+	/**
+	 * Destroys all contained service instances that implement the DestructibleService
+	 * interface. This will render all services obtained from this MediaWikiServices
+	 * instance unusable. In particular, this will disable access to the storage backend
+	 * via any of these services. Any future call to getService() will throw an exception.
+	 *
+	 * @see resetGlobalInstance()
+	 */
+	public function destroy() {
+		foreach ( $this->getServiceNames() as $name ) {
+			$service = $this->peekService( $name );
+			if ( $service !== null && $service instanceof DestructibleService ) {
+				$service->destroy();
+			}
+		}
+
+		$this->destroyed = true;
+	}
+
+	/**
+	 * @param array $wiringFiles A list of PHP files to load wiring information from.
+	 * Each file is loaded using PHP's include mechanism. Each file is expected to
+	 * return an associative array that maps service names to instantiator functions.
+	 */
+	public function loadWiringFiles( array $wiringFiles ) {
+		foreach ( $wiringFiles as $file ) {
+			// the wiring file is required to return an array of instantiators.
+			$wiring = require $file;
+
+			Assert::postcondition(
+				is_array( $wiring ),
+				"Wiring file $file is expected to return an array!"
+			);
+
+			$this->applyWiring( $wiring );
+		}
+	}
+
+	/**
+	 * Registers multiple services (aka a "wiring").
+	 *
+	 * @param array $serviceInstantiators An associative array mapping service names to
+	 *        instantiator functions.
+	 */
+	public function applyWiring( array $serviceInstantiators ) {
+		Assert::parameterElementType( 'callable', $serviceInstantiators, '$serviceInstantiators' );
+
+		foreach ( $serviceInstantiators as $name => $instantiator ) {
+			$this->defineService( $name, $instantiator );
+		}
+	}
+
+	/**
+	 * Imports all wiring defined in $container. Wiring defined in $container
+	 * will override any wiring already defined locally. However, already
+	 * existing service instances will be preserved.
+	 *
+	 * @since 1.28
+	 *
+	 * @param ServiceContainer $container
+	 * @param string[] $skip A list of service names to skip during import
+	 */
+	public function importWiring( ServiceContainer $container, $skip = [] ) {
+		$newInstantiators = array_diff_key(
+			$container->serviceInstantiators,
+			array_flip( $skip )
+		);
+
+		$this->serviceInstantiators = array_merge(
+			$this->serviceInstantiators,
+			$newInstantiators
+		);
+	}
+
+	/**
+	 * Returns true if a service is defined for $name, that is, if a call to getService( $name )
+	 * would return a service instance.
+	 *
+	 * @param string $name
+	 *
+	 * @return bool
+	 */
+	public function hasService( $name ) {
+		return isset( $this->serviceInstantiators[$name] );
+	}
+
+	/**
+	 * Returns the service instance for $name only if that service has already been instantiated.
+	 * This is intended for situations where services get destroyed/cleaned up, so we can
+	 * avoid creating a service just to destroy it again.
+	 *
+	 * @note This is intended for internal use and for test fixtures.
+	 * Application logic should use getService() instead.
+	 *
+	 * @see getService().
+	 *
+	 * @param string $name
+	 *
+	 * @return object|null The service instance, or null if the service has not yet been instantiated.
+	 * @throws RuntimeException if $name does not refer to a known service.
+	 */
+	public function peekService( $name ) {
+		if ( !$this->hasService( $name ) ) {
+			throw new NoSuchServiceException( $name );
+		}
+
+		return isset( $this->services[$name] ) ? $this->services[$name] : null;
+	}
+
+	/**
+	 * @return string[]
+	 */
+	public function getServiceNames() {
+		return array_keys( $this->serviceInstantiators );
+	}
+
+	/**
+	 * Define a new service. The service must not be known already.
+	 *
+	 * @see getService().
+	 * @see replaceService().
+	 *
+	 * @param string $name The name of the service to register, for use with getService().
+	 * @param callable $instantiator Callback that returns a service instance.
+	 *        Will be called with this MediaWikiServices instance as the only parameter.
+	 *        Any extra instantiation parameters provided to the constructor will be
+	 *        passed as subsequent parameters when invoking the instantiator.
+	 *
+	 * @throws RuntimeException if there is already a service registered as $name.
+	 */
+	public function defineService( $name, callable $instantiator ) {
+		Assert::parameterType( 'string', $name, '$name' );
+
+		if ( $this->hasService( $name ) ) {
+			throw new ServiceAlreadyDefinedException( $name );
+		}
+
+		$this->serviceInstantiators[$name] = $instantiator;
+	}
+
+	/**
+	 * Replace an already defined service.
+	 *
+	 * @see defineService().
+	 *
+	 * @note This causes any previously instantiated instance of the service to be discarded.
+	 *
+	 * @param string $name The name of the service to register.
+	 * @param callable $instantiator Callback function that returns a service instance.
+	 *        Will be called with this MediaWikiServices instance as the only parameter.
+	 *        The instantiator must return a service compatible with the originally defined service.
+	 *        Any extra instantiation parameters provided to the constructor will be
+	 *        passed as subsequent parameters when invoking the instantiator.
+	 *
+	 * @throws RuntimeException if $name is not a known service.
+	 */
+	public function redefineService( $name, callable $instantiator ) {
+		Assert::parameterType( 'string', $name, '$name' );
+
+		if ( !$this->hasService( $name ) ) {
+			throw new NoSuchServiceException( $name );
+		}
+
+		if ( isset( $this->services[$name] ) ) {
+			throw new CannotReplaceActiveServiceException( $name );
+		}
+
+		$this->serviceInstantiators[$name] = $instantiator;
+		unset( $this->disabled[$name] );
+	}
+
+	/**
+	 * Disables a service.
+	 *
+	 * @note Attempts to call getService() for a disabled service will result
+	 * in a DisabledServiceException. Calling peekService for a disabled service will
+	 * return null. Disabled services are listed by getServiceNames(). A disabled service
+	 * can be enabled again using redefineService().
+	 *
+	 * @note If the service was already active (that is, instantiated) when getting disabled,
+	 * and the service instance implements DestructibleService, destroy() is called on the
+	 * service instance.
+	 *
+	 * @see redefineService()
+	 * @see resetService()
+	 *
+	 * @param string $name The name of the service to disable.
+	 *
+	 * @throws RuntimeException if $name is not a known service.
+	 */
+	public function disableService( $name ) {
+		$this->resetService( $name );
+
+		$this->disabled[$name] = true;
+	}
+
+	/**
+	 * Resets a service by dropping the service instance.
+	 * If the service instances implements DestructibleService, destroy()
+	 * is called on the service instance.
+	 *
+	 * @warning This is generally unsafe! Other services may still retain references
+	 * to the stale service instance, leading to failures and inconsistencies. Subclasses
+	 * may use this method to reset specific services under specific instances, but
+	 * it should not be exposed to application logic.
+	 *
+	 * @note This is declared final so subclasses can not interfere with the expectations
+	 * disableService() has when calling resetService().
+	 *
+	 * @see redefineService()
+	 * @see disableService().
+	 *
+	 * @param string $name The name of the service to reset.
+	 * @param bool $destroy Whether the service instance should be destroyed if it exists.
+	 *        When set to false, any existing service instance will effectively be detached
+	 *        from the container.
+	 *
+	 * @throws RuntimeException if $name is not a known service.
+	 */
+	final protected function resetService( $name, $destroy = true ) {
+		Assert::parameterType( 'string', $name, '$name' );
+
+		$instance = $this->peekService( $name );
+
+		if ( $destroy && $instance instanceof DestructibleService ) {
+			$instance->destroy();
+		}
+
+		unset( $this->services[$name] );
+		unset( $this->disabled[$name] );
+	}
+
+	/**
+	 * Returns a service object of the kind associated with $name.
+	 * Services instances are instantiated lazily, on demand.
+	 * This method may or may not return the same service instance
+	 * when called multiple times with the same $name.
+	 *
+	 * @note Rather than calling this method directly, it is recommended to provide
+	 * getters with more meaningful names and more specific return types, using
+	 * a subclass or wrapper.
+	 *
+	 * @see redefineService().
+	 *
+	 * @param string $name The service name
+	 *
+	 * @throws NoSuchServiceException if $name is not a known service.
+	 * @throws ContainerDisabledException if this container has already been destroyed.
+	 * @throws ServiceDisabledException if the requested service has been disabled.
+	 *
+	 * @return object The service instance
+	 */
+	public function getService( $name ) {
+		if ( $this->destroyed ) {
+			throw new ContainerDisabledException();
+		}
+
+		if ( isset( $this->disabled[$name] ) ) {
+			throw new ServiceDisabledException( $name );
+		}
+
+		if ( !isset( $this->services[$name] ) ) {
+			$this->services[$name] = $this->createService( $name );
+		}
+
+		return $this->services[$name];
+	}
+
+	/**
+	 * @param string $name
+	 *
+	 * @throws InvalidArgumentException if $name is not a known service.
+	 * @return object
+	 */
+	private function createService( $name ) {
+		if ( isset( $this->serviceInstantiators[$name] ) ) {
+			$service = call_user_func_array(
+				$this->serviceInstantiators[$name],
+				array_merge( [ $this ], $this->extraInstantiationParams )
+			);
+			// NOTE: when adding more wiring logic here, make sure copyWiring() is kept in sync!
+		} else {
+			throw new NoSuchServiceException( $name );
+		}
+
+		return $service;
+	}
+
+	/**
+	 * @param string $name
+	 * @return bool Whether the service is disabled
+	 * @since 1.28
+	 */
+	public function isServiceDisabled( $name ) {
+		return isset( $this->disabled[$name] );
+	}
+}
diff --git a/www/wiki/includes/services/ServiceDisabledException.php b/www/wiki/includes/services/ServiceDisabledException.php
new file mode 100644
index 00000000..ae15b7ce
--- /dev/null
+++ b/www/wiki/includes/services/ServiceDisabledException.php
@@ -0,0 +1,43 @@
+<?php
+namespace MediaWiki\Services;
+
+use Exception;
+use RuntimeException;
+
+/**
+ * Exception thrown when trying to access a disabled service.
+ *
+ * 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
+ *
+ * @since 1.27
+ */
+
+/**
+ * Exception thrown when trying to access a disabled service.
+ */
+class ServiceDisabledException extends RuntimeException {
+
+	/**
+	 * @param string $serviceName
+	 * @param Exception|null $previous
+	 */
+	public function __construct( $serviceName, Exception $previous = null ) {
+		parent::__construct( "Service disabled: $serviceName", 0, $previous );
+	}
+
+}