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.flink.translation.wrappers.streaming.stableinput;
  
  import java.util.stream.Stream;
  
  /**
   * A handler for buffering elements which cannot be processed yet because {@link
   * org.apache.beam.sdk.transforms.DoFn.RequiresStableInput} is used and a checkpoint is currently
   * pending.
   *
   * <p>When a DoFn is annotated with @RequiresStableInput we are only allowed to process elements
   * after a checkpoint has completed. This ensures that the input is stable and we produce idempotent
   * results on failures.
   */
  interface BufferingElementsHandler {
  
    /** Returns all buffered elements. */
    Stream<BufferedElement> getElements();
  
    /** Adds the given element to the buffered elements. */
    void buffer(BufferedElement element);
  
    /** Clears buffered elements. */
    void clear();
  }
  