/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.openejb.client;
import org.apache.openejb.client.event.FailoverSelection;
import org.apache.openejb.client.event.RandomFailoverSelection;
import java.net.URI;
import java.util.Arrays;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Random;
import java.util.Set;
public class RandomConnectionStrategy extends AbstractConnectionStrategy {
@Override
protected FailoverSelection createFailureEvent(Set<URI> remaining, Set<URI> failed, URI uri) {
return new RandomFailoverSelection(remaining, failed, uri);
}
@Override
protected Iterable<URI> createIterable(ClusterMetaData cluster) {
return new RandomIterable(cluster);
}
public static class RandomIterable implements Iterable<URI> {
private final URI[] locations;
public RandomIterable(ClusterMetaData clusterMetaData) {
this.locations = clusterMetaData.getLocations();
}
@Override
public Iterator<URI> iterator() {
return new RandomIterator<URI>(locations);
}
}
public static class RandomIterator<T> implements Iterator<T> {
private final Random random = new Random();
private final T[] items;
private int size;
public RandomIterator(T[] items) {
this.items = Arrays.copyOf(items, items.length);
this.size = items.length;
}
@Override
public boolean hasNext() {
return size > 0;
}
@Override
public T next() {
if (!hasNext()) throw new NoSuchElementException();
// Random.nextInt is exclusive.
// So if size=10, result will be between 0-9
final int selected = random.nextInt(size--);
T selectedObject = items[selected];
// Take the object from the end of the list
// and move it into the place where selected was.
items[selected] = items[size];
items[size] = null;
return selectedObject;
}
@Override
public void remove() {
throw new UnsupportedOperationException("remove");
}
}
}