/*
* Copyright (c) 2008-2011, Rickard Öberg. All Rights Reserved.
* Copyright (c) 2008-2013, Niclas Hedhman. All Rights Reserved.
* Copyright (c) 2012-2014, Paul Merlin. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied.
*
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.qi4j.runtime.service;
import java.lang.reflect.Method;
import org.qi4j.api.activation.Activation;
import org.qi4j.api.activation.ActivationEventListener;
import org.qi4j.api.activation.ActivationException;
import org.qi4j.api.activation.PassivationException;
import org.qi4j.api.composite.CompositeDescriptor;
import org.qi4j.api.composite.CompositeInstance;
import org.qi4j.api.property.StateHolder;
import org.qi4j.api.service.ServiceDescriptor;
import org.qi4j.api.service.ServiceImporterException;
import org.qi4j.api.service.ServiceReference;
import org.qi4j.api.service.ServiceUnavailableException;
import org.qi4j.api.structure.Module;
import org.qi4j.runtime.activation.ActivationDelegate;
import org.qi4j.runtime.structure.ModuleInstance;
/**
* Implementation of ServiceReference.
* <p>
* This manages the actual instance of the service and implements the service Activation.
* </p>
* <p>
* Whenever the service is requested a proxy is returned which points to this class. This means
* that the instance can be passivated even though a client is holding on to a service proxy.
* </p>
* @param <T> Service Type
*/
public final class ServiceReferenceInstance<T>
implements ServiceReference<T>, Activation
{
private volatile ServiceInstance instance;
private final T serviceProxy;
private final ModuleInstance module;
private final ServiceModel serviceModel;
private final ActivationDelegate activation = new ActivationDelegate( this );
private boolean active = false;
public ServiceReferenceInstance( ServiceModel serviceModel, ModuleInstance module )
{
this.module = module;
this.serviceModel = serviceModel;
serviceProxy = newProxy();
}
@Override
public String identity()
{
return serviceModel.identity();
}
@Override
public Iterable<Class<?>> types()
{
return serviceModel.types();
}
@Override
public <T> T metaInfo( Class<T> infoType )
{
return serviceModel.metaInfo( infoType );
}
@Override
public synchronized T get()
{
return serviceProxy;
}
@Override
public boolean isActive()
{
return active;
}
@Override
public boolean isAvailable()
{
return getInstance().isAvailable();
}
public Module module()
{
return module;
}
@Override
public void activate()
throws ActivationException
{
if( serviceModel.isInstantiateOnStartup() )
{
getInstance();
}
}
@Override
public void passivate()
throws PassivationException
{
if( instance != null )
{
try {
activation.passivate( new Runnable()
{
@Override
public void run()
{
active = false;
}
} );
} finally {
instance = null;
active = false;
}
}
}
private ServiceInstance getInstance()
throws ServiceImporterException
{
// DCL that works with Java 1.5 volatile semantics
if( instance == null )
{
synchronized( this )
{
if( instance == null )
{
instance = serviceModel.newInstance( module );
try
{
activation.activate( serviceModel.newActivatorsInstance( module ), instance, new Runnable()
{
@Override
public void run()
{
active = true;
}
} );
}
catch( Exception e )
{
instance = null;
throw new ServiceUnavailableException( "Could not activate service " + serviceModel.identity(), e );
}
}
}
}
return instance;
}
@Override
public String toString()
{
return serviceModel.identity() + "(active=" + isActive() + ",module='" + module.name() + "')";
}
@SuppressWarnings( "unchecked" )
public T newProxy()
{
return (T) serviceModel.newProxy( new ServiceReferenceInstance.ServiceInvocationHandler() );
}
public ServiceDescriptor serviceDescriptor()
{
return serviceModel;
}
public final class ServiceInvocationHandler
implements CompositeInstance
{
@Override
@SuppressWarnings( "unchecked" )
public <T> T proxy()
{
return (T) ServiceReferenceInstance.this.get();
}
@Override
public <T> T newProxy( Class<T> mixinType )
throws IllegalArgumentException
{
return getInstance().newProxy( mixinType );
}
@Override
public <T> T metaInfo( Class<T> infoType )
{
return ServiceReferenceInstance.this.metaInfo( infoType );
}
@Override
public Iterable<Class<?>> types()
{
return ServiceReferenceInstance.this.types();
}
@Override
public CompositeDescriptor descriptor()
{
return ServiceReferenceInstance.this.serviceDescriptor();
}
@Override
public Object invokeComposite( Method method, Object[] args )
throws Throwable
{
return getInstance().invokeComposite( method, args );
}
@Override
public StateHolder state()
{
return getInstance().state();
}
@Override
public Object invoke( Object object, Method method, Object[] objects )
throws Throwable
{
if( method.getDeclaringClass().equals( Object.class ) )
{
switch( method.getName() )
{
case "toString":
return serviceModel.toString();
case "equals":
return objects[0] == object;
case "hashCode":
return serviceModel.toString().hashCode();
}
}
ServiceInstance instance = getInstance();
/*
if (!instance.isAvailable())
{
throw new ServiceUnavailableException("Service is currently not available");
}
*/
return instance.invoke( object, method, objects );
}
@Override
public String toString()
{
return serviceModel.toString();
}
@Override
public Module module()
{
return module;
}
}
@Override
public void registerActivationEventListener( ActivationEventListener listener )
{
activation.registerActivationEventListener( listener );
}
@Override
public void deregisterActivationEventListener( ActivationEventListener listener )
{
activation.deregisterActivationEventListener( listener );
}
@Override
public int hashCode()
{
return identity().hashCode();
}
@Override
@SuppressWarnings( "raw" )
public boolean equals( Object obj )
{
if ( obj == null ) {
return false;
}
if ( getClass() != obj.getClass() ) {
return false;
}
final ServiceReference other = ( ServiceReference ) obj;
return identity().equals( other.identity() );
}
}