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.beam.sdk.transforms.splittabledofn;
  
  import org.apache.beam.sdk.transforms.DoFn;
  import org.joda.time.Instant;
  
  /**
   * A {@link WatermarkEstimator} which is controlled manually from within a {@link DoFn}. The {@link
   * DoFn} must invoke {@link #setWatermark} to advance the watermark. See {@link
   * WatermarkEstimators.Manual} for a concrete implementation.
   */
  public interface ManualWatermarkEstimator<WatermarkEstimatorStateT>
      extends WatermarkEstimator<WatermarkEstimatorStateT> {
  
    /**
     * Sets a timestamp before or at the timestamps of all future elements produced by the associated
     * DoFn.
     *
     * <p>This can be approximate. If records are output that violate this guarantee, they will be
     * considered late, which will affect how they will be processed. See <a
     * href="https://beam.apache.org/documentation/programming-guide/#watermarks-and-late-data">watermarks
     * and late data</a> for more information on late data and how to handle it.
     *
     * <p>However, this value should be as late as possible. Downstream windows may not be able to
     * close until this watermark passes their end.
     */
    void setWatermark(Instant watermark);
  }
  