/*
* JBoss, Home of Professional Open Source.
* Copyright 2016, Red Hat, Inc., and individual contributors
* as indicated by the @author tags. See the copyright.txt file in the
* distribution for a full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.wildfly.clustering.service;
import java.util.function.BiConsumer;
import java.util.function.Function;
import org.jboss.logging.Logger;
import org.jboss.msc.service.Service;
import org.jboss.msc.service.StartContext;
import org.jboss.msc.service.StartException;
import org.jboss.msc.service.StopContext;
import org.wildfly.common.function.ExceptionFunction;
/**
* Generic {@link Service} whose value is created and destroyed by contextual functions.
* @author Paul Ferraro
*/
public class FunctionalValueService<T, V> implements Service<V> {
private static final Logger LOGGER = Logger.getLogger(FunctionalValueService.class);
private final Function<T, V> mapper;
private final ExceptionFunction<StartContext, T, StartException> factory;
private final BiConsumer<StopContext, T> destroyer;
private volatile T value;
/**
* Constructs a new functional value service.
* @param mapper a function that maps the result of the factory function to the service value
* @param factory a function that creates a value
* @param destroyer a consumer that destroys the value created by the factory function
*/
public FunctionalValueService(Function<T, V> mapper, ExceptionFunction<StartContext, T, StartException> factory, BiConsumer<StopContext, T> destroyer) {
this.mapper = mapper;
this.factory = factory;
this.destroyer = destroyer;
}
@Override
public V getValue() {
return this.mapper.apply(this.value);
}
@Override
public void start(StartContext context) throws StartException {
try {
this.value = this.factory.apply(context);
} catch (RuntimeException | Error e) {
throw new StartException(e);
}
}
@Override
public void stop(StopContext context) {
if (this.destroyer != null) {
try {
this.destroyer.accept(context, this.value);
} catch (RuntimeException | Error e) {
LOGGER.warn(e.getLocalizedMessage(), e);
} finally {
this.value = null;
}
}
}
}