content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.table.common;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.ServiceLoader;
  
  /**
   * The registry of layout implementations.
   */
  public class LayoutRegistry {
    private static final Logger LOG = LoggerFactory.getLogger(LayoutRegistry.class);
  
    private volatile Map<String, LayoutFactory> mFactories;
  
    /**
     * Creates an instance.
     */
    public LayoutRegistry() {
      mFactories = new HashMap<>();
    }
  
    /**
     * Refreshes the registry by service loading classes.
     */
    public void refresh() {
      Map<String, LayoutFactory> map = new HashMap<>();
      for (LayoutFactory factory : ServiceLoader
          .load(LayoutFactory.class, LayoutRegistry.class.getClassLoader())) {
        LayoutFactory existingFactory = map.get(factory.getType());
        if (existingFactory != null) {
          LOG.warn(
              "Ignoring duplicate layout type '{}' found in factory {}. Existing factory: {}",
              factory.getType(), factory.getClass(), existingFactory.getClass());
        }
        map.put(factory.getType(), factory);
      }
      mFactories = map;
      LOG.info("Registered Table Layouts: " + String.join(",", mFactories.keySet()));
    }
  
    /**
     * Creates a new instance of a {@link Layout}.
     *
     * @param layoutProto the proto representation of the layout
     * @return a new instance of the layout
     */
    public Layout create(alluxio.grpc.table.Layout layoutProto) {
      Map<String, LayoutFactory> map = mFactories;
      String type = layoutProto.getLayoutType();
      LayoutFactory factory = map.get(type);
      if (factory == null) {
        throw new IllegalStateException(
            String.format("LayoutFactory for type '%s' does not exist.", type));
      }
      return factory.create(layoutProto);
    }
  }
  