org.apache.whirr.ClusterControllerFactory.java Source code

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Here is the source code for org.apache.whirr.ClusterControllerFactory.java

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/**
 * 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.whirr;

import java.util.ServiceLoader;
import java.util.Set;

import com.google.common.collect.Sets;

/**
 * This class is used to create {@link ClusterController} instances.
 * <p>
 * <i>Implementation note.</i> {@link ClusterController} implementations are discovered
 * using a Service Provider
 * Interface (SPI), described in {@link ServiceLoader}.
 */
public class ClusterControllerFactory {

    private ServiceLoader<ClusterController> serviceLoader = ServiceLoader.load(ClusterController.class);

    /**
     * Create an instance of a {@link ClusterController} according to the given
     * name. If the name is <code>null</code> then the default {@link ClusterController}
     * is returned.
     */
    public ClusterController create(String serviceName) {
        if (serviceName == null) {
            return new ClusterController();
        }
        for (ClusterController controller : serviceLoader) {
            if (controller.getName().equals(serviceName)) {
                return controller;
            }
        }
        return null;
    }

    /**
     * Return a collection of available {@link ClusterController} names.
     * @return the available service names
     */
    public Set<String> availableServices() {
        Set<String> result = Sets.newLinkedHashSet();
        for (ClusterController s : serviceLoader) {
            result.add(s.getName());
        }
        return result;
    }
}