/*
* 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 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.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.slf4j.LoggerFactory;
/**
* Implementation of ServiceReference. This manages the reference to the imported service.
* <p>
* Whenever the service is requested it is returned directly to the client. That means that
* to handle service passivation and unavailability correctly, any proxying must be done in the
* service importer.
* </p>
* @param <T> Service Type
*/
public final class ImportedServiceReferenceInstance<T>
implements ServiceReference<T>, Activation
{
private volatile ImportedServiceInstance<T> serviceInstance;
private T instance;
private final Module module;
private final ImportedServiceModel serviceModel;
private final ActivationDelegate activation = new ActivationDelegate( this );
private boolean active = false;
public ImportedServiceReferenceInstance( ImportedServiceModel serviceModel, Module module )
{
this.module = module;
this.serviceModel = serviceModel;
}
@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 getInstance();
}
public ImportedServiceModel serviceDescriptor()
{
return serviceModel;
}
@Override
public void activate()
throws ActivationException
{
if( serviceModel.isImportOnStartup() )
{
getInstance();
}
}
@Override
public void passivate()
throws PassivationException
{
if( serviceInstance != null )
{
try
{
activation.passivate( new Runnable()
{
@Override
public void run()
{
active = false;
}
} );
}
finally
{
serviceInstance = null;
active = false;
}
}
}
@Override
public boolean isActive()
{
return active;
}
@Override
public boolean isAvailable()
{
try
{
getInstance();
return serviceInstance.isAvailable();
}
catch( ServiceImporterException ex )
{
LoggerFactory.getLogger( getClass() )
.warn( "Imported service throwed an exception on isAvailable(), will return false.", ex );
return false;
}
}
public Module module()
{
return module;
}
private T getInstance()
throws ServiceImporterException
{
// DCL that works with Java 1.5 volatile semantics
if( serviceInstance == null )
{
synchronized( this )
{
if( serviceInstance == null )
{
serviceInstance = serviceModel.<T>importInstance( module );
instance = serviceInstance.instance();
try
{
activation.activate( serviceModel.newActivatorsInstance( module ), serviceInstance, new Runnable()
{
@Override
public void run()
{
active = true;
}
} );
}
catch( Exception e )
{
serviceInstance = null;
throw new ServiceUnavailableException( "Could not activate service " + serviceModel.identity(), e );
}
}
}
}
return instance;
}
@Override
public String toString()
{
return serviceModel.identity() + ", active=" + isActive() + ", module='" + serviceModel.moduleName() + "'";
}
@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
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() );
}
}