Wikimedia\Services\ServiceContainer Class Reference

ServiceContainer provides a generic service to manage named services using lazy instantiation based on instantiator callback functions. More...

Inheritance diagram for Wikimedia\Services\ServiceContainer:

Public Member Functions
	__construct (array $extraInstantiationParams=[])
	destroy ()
	Destroys all contained service instances that implement the DestructibleService interface.
	loadWiringFiles (array $wiringFiles)
	applyWiring (array $serviceInstantiators)
	Registers multiple services (aka a "wiring").
	importWiring (ServiceContainer $container, array $skip=[])
	Imports all wiring defined in $container.
	hasService (string $name)
	Returns true if a service is defined for $name, that is, if a call to getService( $name ) would return a service instance.
	has (string $name)
	@inheritDoc
	peekService (string $name)
	Returns the service instance for $name only if that service has already been instantiated.
	getServiceNames ()
	defineService (string $name, callable $instantiator)
	Define a new service.
	redefineService (string $name, callable $instantiator)
	Replace an already defined service.
	addServiceManipulator (string $name, callable $manipulator)
	Add a service manipulator callback for the given service.
	disableService (string $name)
	Disables a service.
	getService (string $name)
	Returns a service of the kind associated with $name.
	get (string $name)
	@inheritDoc
	isServiceDisabled (string $name)

Protected Member Functions
	resetService (string $name, bool $destroy=true)
	Resets a service by dropping the service instance.

Detailed Description

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 also

MediaWiki core's docs/Injection.md for an overview of using dependency injection in that code base.

Constructor & Destructor Documentation

__construct()

Wikimedia\Services\ServiceContainer::__construct

(

array

$extraInstantiationParams = []

)

Parameters

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.

Member Function Documentation

addServiceManipulator()

Wikimedia\Services\ServiceContainer::addServiceManipulator	(	string	$name,
		callable	$manipulator )

Add a service manipulator callback for the given service.

This method may be used by extensions that need to wrap, replace, or re-configure a service. It would typically be called from a MediaWikiServices hook handler.

The manipulator callback is called just after the service is instantiated. It can call methods on the service to change configuration, or wrap or otherwise replace it.

See also

defineService().

redefineService().

Note

This will fail if the service was already instantiated.

Since

1.32

Parameters

string	$name	The name of the service to manipulate.
callable	$manipulator	Callback function that manipulates, wraps or replaces a service instance. The callback receives the new service instance and this ServiceContainer as parameters, as well as any extra instantiation parameters specified when constructing this ServiceContainer. If the callback returns a value, that value replaces the original service instance.

Exceptions

NoSuchServiceException	if $name is not a known service.
CannotReplaceActiveServiceException	if the service was already instantiated.

applyWiring()

Wikimedia\Services\ServiceContainer::applyWiring

(

array

$serviceInstantiators

)

Registers multiple services (aka a "wiring").

Parameters

callable[]

$serviceInstantiators

An associative array mapping service names to instantiator functions.

defineService()

Wikimedia\Services\ServiceContainer::defineService	(	string	$name,
		callable	$instantiator )

Define a new service.

The service must not be known already.

See also

getService().

redefineService().

Parameters

string	$name	The name of the service to register, for use with getService().
callable	$instantiator	Callback that returns a service instance. Will be called with this ServiceContainer instance as the only parameter. Any extra instantiation parameters provided to the constructor will be passed as subsequent parameters when invoking the instantiator.

Exceptions

RuntimeException

if there is already a service registered as $name.

destroy()

Wikimedia\Services\ServiceContainer::destroy

(

)

Destroys all contained service instances that implement the DestructibleService interface.

This will render all services obtained from this ServiceContainer 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 also

MediaWikiServices::resetGlobalInstance()

Implements Wikimedia\Services\DestructibleService.

disableService()

true[] Set of services that got disabled via see Wikimedia\Services\ServiceContainer::disableService

(

string

$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().

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 also

redefineService()

resetService()

Parameters

string

$name

The name of the service to disable.

getService()

Wikimedia\Services\ServiceContainer::getService

(

string

$name

)

Returns a service 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 also

redefineService().

Parameters

string

$name

The service name

Exceptions

NoSuchServiceException	if $name is not a known service.
ContainerDisabledException	if this container has already been destroyed.
ServiceDisabledException	if the requested service has been disabled.

Returns

mixed The service instance

getServiceNames()

Wikimedia\Services\ServiceContainer::getServiceNames

(

)

Returns

string[]

hasService()

Wikimedia\Services\ServiceContainer::hasService

(

string

$name

)

Returns true if a service is defined for $name, that is, if a call to getService( $name ) would return a service instance.

Parameters

string

$name

Returns

bool

importWiring()

Wikimedia\Services\ServiceContainer::importWiring	(	ServiceContainer	$container,
		array	$skip = [] )

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

Parameters

ServiceContainer	$container
string[]	$skip	A list of service names to skip during import

isServiceDisabled()

Wikimedia\Services\ServiceContainer::isServiceDisabled

(

string

$name

)

Parameters

string

$name

Returns

bool Whether the service is disabled

Since

1.28

loadWiringFiles()

Wikimedia\Services\ServiceContainer::loadWiringFiles

(

array

$wiringFiles

)

Parameters

string[]

$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.

peekService()

Wikimedia\Services\ServiceContainer::peekService

(

string

$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 also

getService().

Parameters

string

$name

Returns

mixed|null The service instance, or null if the service has not yet been instantiated.

Exceptions

RuntimeException

if $name does not refer to a known service.

redefineService()

Wikimedia\Services\ServiceContainer::redefineService	(	string	$name,
		callable	$instantiator )

Replace an already defined service.

See also

defineService().

Note

This will fail if the service was already instantiated. If the service was previously disabled, it will be re-enabled by this call. Any manipulators registered for the service will remain in place.

Parameters

string	$name	The name of the service to register.
callable	$instantiator	Callback function that returns a service instance. Will be called with this ServiceContainer 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.

Exceptions

NoSuchServiceException	if $name is not a known service.
CannotReplaceActiveServiceException	if the service was already instantiated.

resetService()

Wikimedia\Services\ServiceContainer::resetService ( string $name, bool $destroy = true )

finalprotected

Resets a service by dropping the service instance.

If the service instance 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 also

redefineService()

disableService().

Parameters

string	$name	The name of the service to reset.
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.

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The documentation for this class was generated from the following file:

• src/ServiceContainer.php