/*******************************************************************************
* Copyright (c) 2008, 2014 Stuart McCulloch
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Stuart McCulloch - initial API and implementation
*******************************************************************************/
package org.eclipse.sisu.peaberry.cache;
import java.util.Arrays;
import java.util.Iterator;
import javax.inject.Inject;
import org.eclipse.sisu.peaberry.AttributeFilter;
import org.eclipse.sisu.peaberry.Export;
import org.eclipse.sisu.peaberry.Import;
import org.eclipse.sisu.peaberry.ServiceRegistry;
import org.eclipse.sisu.peaberry.ServiceWatcher;
/**
* A {@link ServiceRegistry} that delegates to a series of other registries.
*
* @author mcculls@gmail.com (Stuart McCulloch)
*/
public class RegistryChain
implements ServiceRegistry {
private final ServiceRegistry[] registries;
@Inject
public RegistryChain(@Chain final ServiceRegistry mainRegistry,
@Chain final ServiceRegistry[] extraRegistries) {
// merge main and additional registries into a single array
registries = new ServiceRegistry[1 + extraRegistries.length];
System.arraycopy(extraRegistries, 0, registries, 1, extraRegistries.length);
registries[0] = mainRegistry;
}
public final <T> Iterable<Import<T>> lookup(final Class<T> clazz, final AttributeFilter filter) {
@SuppressWarnings("unchecked")
final Iterable<Import<T>>[] lazyIterables = new Iterable[registries.length];
// support lazy lookup from multiple registries
for (int i = 0; i < registries.length; i++) {
final ServiceRegistry reg = registries[i];
lazyIterables[i] = new Iterable<Import<T>>() { // NOPMD
private volatile Iterable<Import<T>> iterable;
// delay lookup until absolutely necessary
public Iterator<Import<T>> iterator() {
if (null == iterable) {
synchronized (this) {
if (null == iterable) {
iterable = reg.lookup(clazz, filter);
}
}
}
return iterable.iterator();
}
};
}
// chain the iterators together
return new Iterable<Import<T>>() {
public Iterator<Import<T>> iterator() {
return new IteratorChain<Import<T>>(lazyIterables);
}
};
}
public final <T> void watch(final Class<T> clazz, final AttributeFilter filter,
final ServiceWatcher<? super T> watcher) {
for (final ServiceRegistry r : registries) {
try {
r.watch(clazz, filter, watcher); // attempt to watch all of them
} catch (final UnsupportedOperationException e) {/* unable to watch */} // NOPMD
}
}
public final <T> Export<T> add(final Import<T> service) {
return registries[0].add(service); // only add to main repository
}
@Override
public final String toString() {
return String.format("RegistryChain%s", Arrays.toString(registries));
}
@Override
public final int hashCode() {
return Arrays.hashCode(registries);
}
@Override
public final boolean equals(final Object rhs) {
if (rhs instanceof RegistryChain) {
return Arrays.equals(registries, ((RegistryChain) rhs).registries);
}
return false;
}
}