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.transform.action;
  
  import com.google.common.annotations.VisibleForTesting;
  import org.apache.commons.lang3.StringUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.List;
  import java.util.Properties;
  import java.util.ServiceLoader;
  
  /**
   * The registry of transform actions.
   */
  public class TransformActionRegistry {
    private static final Logger LOG = LoggerFactory.getLogger(TransformActionRegistry.class);
  
    // List of TransformActionFactories ordered in the order returned by getOrder
    private static final List<TransformActionFactory> FACTORIES = new ArrayList<>();
  
    static {
      refresh();
    }
  
    private TransformActionRegistry() {} // prevent instantiation
  
    /**
     * Creates a new instance of an ordered list of {@link TransformAction}.
     * The ordering here is the order that the Actions should be executed in.
     *
     * @param definition the raw definition of the action
     * @return a new instance of an action
     */
    public static List<TransformAction> create(Properties definition) {
      final ArrayList<TransformAction> actions = new ArrayList<>();
      for (TransformActionFactory factory : FACTORIES) {
        // TODO(bradyoo): make this more efficient when FACTORIES.size() > 50
        final TransformAction transformAction = factory.create(definition);
        if (transformAction != null) {
          actions.add(transformAction);
        }
      }
      return actions;
    }
  
    /**
     * @return the list of TransformActionFactories
     */
    @VisibleForTesting
    public static List<TransformActionFactory> getFactories() {
      return Collections.unmodifiableList(FACTORIES);
    }
  
    /**
     * Refreshes the registry by service loading classes.
     */
    private static void refresh() {
      FACTORIES.clear();
      for (TransformActionFactory factory : ServiceLoader
          .load(TransformActionFactory.class, TransformActionFactory.class.getClassLoader())) {
        FACTORIES.add(factory);
      }
      FACTORIES.sort(Comparator.comparingInt((factory) -> factory.getOrder()));
  
      LOG.info("Registered Transform actions: " + StringUtils.join(FACTORIES, ","));
    }
  }
  