content: /*
   * Licensed 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.bookkeeper.metadata.etcd.helpers;
  
  import java.util.function.Consumer;
  import org.apache.bookkeeper.versioning.Version;
  import org.apache.bookkeeper.versioning.Version.Occurred;
  import org.apache.bookkeeper.versioning.Versioned;
  
  /**
   * A consumer that cache last version.
   */
  public class RevisionedConsumer<T> implements Consumer<Versioned<T>> {
  
      protected final Consumer<Versioned<T>> consumer;
      protected volatile Version localVersion = null;
  
      protected RevisionedConsumer(Consumer<Versioned<T>> consumer) {
          this.consumer = consumer;
      }
  
      @Override
      public void accept(Versioned<T> versionedVal) {
          synchronized (this) {
              if (localVersion != null
                  && Occurred.BEFORE != localVersion.compare(versionedVal.getVersion())) {
                  return;
              }
              localVersion = versionedVal.getVersion();
          }
          consumer.accept(versionedVal);
      }
  
      @Override
      public int hashCode() {
          return consumer.hashCode();
      }
  
      @Override
      public boolean equals(Object obj) {
          if (!(obj instanceof Consumer)) {
              return false;
          }
          if (obj instanceof RevisionedConsumer) {
              return consumer.equals(((RevisionedConsumer) obj).consumer);
          } else {
              return consumer.equals(obj);
          }
      }
  
      @Override
      public String toString() {
          return consumer.toString();
      }
  }
  