geode-core/src/main/java/org/apache/geode/internal/deployment/DeploymentServiceFactory.java

/*
 * 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.geode.internal.deployment;

import java.util.ServiceLoader;

import org.apache.logging.log4j.Logger;

import org.apache.geode.annotations.Experimental;
import org.apache.geode.deployment.internal.exception.ServiceLoadingFailureException;
import org.apache.geode.internal.classloader.ClasspathService;
import org.apache.geode.logging.internal.log4j.api.LogService;

/**
 * Factory responsible for loading and holding the singleton instances of the
 * {@link JarDeploymentService} and {@link ClasspathService}.
 * Use this class to retrieve the instances rather than creating one.
 *
 * @since Geode 1.15
 */
@Experimental
public class DeploymentServiceFactory {

  private static final Logger logger = LogService.getLogger();

  private static JarDeploymentService createJarDeploymentService() {
    ServiceLoader<JarDeploymentService> jarDeploymentServices =
        ServiceLoader.load(JarDeploymentService.class);
    if (jarDeploymentServices.iterator().hasNext()) {
      JarDeploymentService jarDeploymentService = jarDeploymentServices.iterator().next();
      return jarDeploymentService;
    } else {
      throw new ServiceLoadingFailureException(
          "No implementation of JarDeploymentService could be loaded.");
    }
  }

  private static ClasspathService createClassPathService() {
    ServiceLoader<ClasspathService> jarDeploymentServices =
        ServiceLoader.load(ClasspathService.class);
    if (jarDeploymentServices.iterator().hasNext()) {
      ClasspathService classpathService = jarDeploymentServices.iterator().next();
      return classpathService;
    } else {
      throw new ServiceLoadingFailureException(
          "No implementation of ClasspathService could be loaded.");
    }
  }

  /**
   * Gets the current instance of the {@link JarDeploymentService}.
   *
   * @return current instance of the {@link JarDeploymentService}.
   */
  public static JarDeploymentService getJarDeploymentServiceInstance() {
    return createJarDeploymentService();
  }

  /**
   * Gets the current instance of the {@link ClasspathService}.
   *
   * @return current instance of the {@link ClasspathService}.
   */
  public static ClasspathService getClasspathServiceInstance() {
    return createClassPathService();
  }
}