org.eclipse.incquery.runtime.api

Class IncQueryEngineManager

java.lang.Object

org.eclipse.incquery.runtime.api.IncQueryEngineManager

public class IncQueryEngineManager
extends java.lang.Object

Global registry of active IncQuery engines.

Manages an IncQueryEngine for each model (more precisely scope), that is created on demand. Managed engines are shared between clients querying the same model.

It is also possible to create private, unmanaged engines that are not shared between clients.

Only weak references are retained on the managed engines. So if there are no other references to the matchers or the engine, they can eventually be GC'ed, and they won't block the model from being GC'ed either.

Author:

Bergmann Gabor

Method Summary

Modifier and Type	Method and Description
void	addIncQueryEngineInitializationListener(IncQueryEngineInitializationListener listener) Registers a listener for new engine initialization.
java.util.Set<IncQueryEngine>	getExistingIncQueryEngines() Collects all IncQueryEngine instances that still exist.
IncQueryEngine	getIncQueryEngine(IncQueryScope scope) Creates a managed IncQuery engine at a given scope (e.g.
IncQueryEngine	getIncQueryEngineIfExists(IncQueryScope scope) Retrieves an already existing managed IncQuery engine.
static IncQueryEngineManager	getInstance()
void	removeIncQueryEngineInitializationListener(IncQueryEngineInitializationListener listener) Removes a registered listener added with addIncQueryEngineInitializationListener(org.eclipse.incquery.runtime.api.IncQueryEngineInitializationListener)

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getInstance

public static IncQueryEngineManager getInstance()

Returns:

the singleton instance

getIncQueryEngine

public IncQueryEngine getIncQueryEngine(IncQueryScope scope)
                                 throws IncQueryException

Creates a managed IncQuery engine at a given scope (e.g. an EMF Resource or ResourceSet, as in EMFScope) or retrieves an already existing one. Repeated invocations for a single model root will return the same engine. Consequently, the engine will be reused between different clients querying the same model, providing performance benefits.

The match set of any patterns will be incrementally refreshed upon updates from this scope.

Parameters:

scope - the scope of query evaluation; the definition of the set of model elements that this engine is operates on. Provide e.g. a EMFScope for evaluating queries on an EMF model.

Returns:

a new or previously existing engine

Throws:

IncQueryException

getIncQueryEngineIfExists

public IncQueryEngine getIncQueryEngineIfExists(IncQueryScope scope)

Retrieves an already existing managed IncQuery engine.

Parameters:

scope - the scope of query evaluation; the definition of the set of model elements that this engine is operates on. Provide e.g. a EMFScope for evaluating queries on an EMF model.

Returns:

a previously existing engine, or null if no engine is active for the given EMF model root

getExistingIncQueryEngines

public java.util.Set<IncQueryEngine> getExistingIncQueryEngines()

Collects all IncQueryEngine instances that still exist.

Returns:

set of engines if there is any, otherwise EMTPY_SET

addIncQueryEngineInitializationListener

public void addIncQueryEngineInitializationListener(IncQueryEngineInitializationListener listener)

Registers a listener for new engine initialization.

For removal, use removeIncQueryEngineInitializationListener(org.eclipse.incquery.runtime.api.IncQueryEngineInitializationListener)

Parameters:

listener - the listener to register

removeIncQueryEngineInitializationListener

public void removeIncQueryEngineInitializationListener(IncQueryEngineInitializationListener listener)

Removes a registered listener added with addIncQueryEngineInitializationListener(org.eclipse.incquery.runtime.api.IncQueryEngineInitializationListener)

Parameters:

listener -