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.runners.core;
  
  import org.apache.beam.sdk.state.TimeDomain;
  import org.apache.beam.sdk.transforms.DoFn;
  import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.joda.time.Instant;
  
  /**
   * Interface for runners of {@link DoFn}'s that support pushback when reading side inputs, i.e.
   * return elements that could not be processed because they require reading a side input window that
   * is not ready.
   */
  public interface PushbackSideInputDoFnRunner<InputT, OutputT> {
    /** Calls the underlying {@link DoFn.StartBundle} method. */
    void startBundle();
  
    /**
     * Call the underlying {@link DoFn.ProcessElement} method for the provided element for each window
     * the element is in that is ready.
     *
     * @param elem the element to process in all ready windows
     * @return each element that could not be processed because it requires a side input window that
     *     is not ready.
     */
    Iterable<WindowedValue<InputT>> processElementInReadyWindows(WindowedValue<InputT> elem);
  
    /** Calls the underlying {@link DoFn.OnTimer} method. */
    <KeyT> void onTimer(
        String timerId,
        String timerFamilyId,
        KeyT key,
        BoundedWindow window,
        Instant timestamp,
        Instant outputTimestamp,
        TimeDomain timeDomain);
  
    /** Calls the underlying {@link DoFn.OnWindowExpiration} method. */
    <KeyT> void onWindowExpiration(BoundedWindow window, Instant outputTimestamp, KeyT key);
  
    /** Calls the underlying {@link DoFn.FinishBundle} method. */
    void finishBundle();
  
    /**
     * @since 2.5.0
     * @return the underlying fn instance.
     */
    DoFn<InputT, OutputT> getFn();
  }
  