content: /*
   * 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.kafka.streams.state.internals;
  
  import org.apache.kafka.streams.KeyValue;
  
  import java.util.Objects;
  
  /**
   * Combines a timestamped key from a {@link KeyValue} with a boolean value referencing if the key is
   * part of the left join (true) or right join (false). This class is only useful when a state
   * store needs to be shared between left and right processors, and each processor needs to
   * access the key of the other processor.
   *
   * Note that it might be cleaner to have two layers for such usages: first a KeyAndJoinSide, where the Key
   * is in the form of a <timestamp, key>; but with the nested structure serdes would need extra byte array copies.
   * Since it is only used in a single place today we decided to combine them into a single type / serde.
   */
  public class TimestampedKeyAndJoinSide<K> {
      private final K key;
      private final long timestamp;
      private final boolean leftSide;
  
      private TimestampedKeyAndJoinSide(final boolean leftSide, final K key, final long timestamp) {
          this.key = Objects.requireNonNull(key, "key cannot be null");
          this.leftSide = leftSide;
          this.timestamp = timestamp;
      }
  
      /**
       * Create a new {@link TimestampedKeyAndJoinSide} instance for the left join side if the provide {@code key} is not {@code null}.
       *
       * @param key      the key
       * @param <K>      the type of the key
       * @return a new {@link TimestampedKeyAndJoinSide} instance for the left join side if the provide {@code key} is not {@code null}
       */
      public static <K> TimestampedKeyAndJoinSide<K> makeLeft(final K key, final long timestamp) {
          return new TimestampedKeyAndJoinSide<>(true, key, timestamp);
      }
      /**
       * Create a new {@link TimestampedKeyAndJoinSide} instance for the right join side if the provide {@code key} is not {@code null}.
       *
       * @param key      the key
       * @param <K>      the type of the key
       * @return a new {@link TimestampedKeyAndJoinSide} instance for the right join side if the provide {@code key} is not {@code null}
       */
      public static <K> TimestampedKeyAndJoinSide<K> makeRight(final K key, final long timestamp) {
          return new TimestampedKeyAndJoinSide<>(false, key, timestamp);
      }
      public boolean isLeftSide() {
          return leftSide;
      }
  
      public K key() {
          return key;
      }
  
      public long timestamp() {
          return timestamp;
      }
  
      @Override
      public String toString() {
          final String joinSide = leftSide ? "left" : "right";
          return "<" + joinSide + "," + key + ":" + timestamp + ">";
      }
  
      @Override
      public boolean equals(final Object o) {
          if (this == o) {
              return true;
          }
          if (o == null || getClass() != o.getClass()) {
              return false;
          }
          final TimestampedKeyAndJoinSide<?> that = (TimestampedKeyAndJoinSide<?>) o;
          return leftSide == that.leftSide &&
              Objects.equals(key, that.key) &&
              timestamp == that.timestamp;
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(leftSide, key, timestamp);
      }
  }
  