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;
  
  import java.util.Objects;
  
  /**
   * Encapsulates information about lag, at a store partition replica (active or standby). This information is constantly changing as the
   * tasks process records and thus, they should be treated as simply instantaneous measure of lag.
   */
  public class LagInfo {
  
      private final long currentOffsetPosition;
  
      private final long endOffsetPosition;
  
      private final long offsetLag;
  
      LagInfo(final long currentOffsetPosition, final long endOffsetPosition) {
          this.currentOffsetPosition = currentOffsetPosition;
          this.endOffsetPosition = endOffsetPosition;
          this.offsetLag = Math.max(0, endOffsetPosition - currentOffsetPosition);
      }
  
      /**
       * Get the current maximum offset on the store partition's changelog topic, that has been successfully written into
       * the store partition's state store.
       *
       * @return current consume offset for standby/restoring store partitions &amp; simply end offset for active store partition replicas
       */
      public long currentOffsetPosition() {
          return this.currentOffsetPosition;
      }
  
      /**
       * Get the end offset position for this store partition's changelog topic on the Kafka brokers.
       *
       * @return last offset written to the changelog topic partition
       */
      public long endOffsetPosition() {
          return this.endOffsetPosition;
      }
  
      /**
       * Get the measured lag between current and end offset positions, for this store partition replica
       *
       * @return lag as measured by message offsets
       */
      public long offsetLag() {
          return this.offsetLag;
      }
  
      @Override
      public boolean equals(final Object obj) {
          if (!(obj instanceof LagInfo)) {
              return false;
          }
          final LagInfo other = (LagInfo) obj;
          return currentOffsetPosition == other.currentOffsetPosition
              && endOffsetPosition == other.endOffsetPosition
              && this.offsetLag == other.offsetLag;
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(currentOffsetPosition, endOffsetPosition, offsetLag);
      }
  
      @Override
      public String toString() {
          return "LagInfo {" +
              " currentOffsetPosition=" + currentOffsetPosition +
              ", endOffsetPosition=" + endOffsetPosition +
              ", offsetLag=" + offsetLag +
              '}';
      }
  }
  