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.util;
  
  import org.apache.beam.sdk.annotations.Internal;
  
  /** Back-off policy when retrying an operation. */
  @Internal
  public interface BackOff {
  
    /** Indicates that no more retries should be made for use in {@link #nextBackOffMillis()}. */
    long STOP = -1L;
  
    /** Reset to initial state. */
    void reset();
  
    /**
     * Gets the number of milliseconds to wait before retrying the operation or {@link #STOP} to
     * indicate that no retries should be made.
     *
     * <p>Example usage:
     *
     * <pre>
     * long backOffMillis = backoff.nextBackOffMillis();
     * if (backOffMillis == Backoff.STOP) {
     * // do not retry operation
     * } else {
     * // sleep for backOffMillis milliseconds and retry operation
     * }
     * </pre>
     */
    long nextBackOffMillis();
  
    /**
     * Fixed back-off policy whose back-off time is always zero, meaning that the operation is retried
     * immediately without waiting.
     */
    BackOff ZERO_BACKOFF =
        new BackOff() {
  
          @Override
          public void reset() {}
  
          @Override
          public long nextBackOffMillis() {
            return 0;
          }
        };
  
    /**
     * Fixed back-off policy that always returns {@code #STOP} for {@link #nextBackOffMillis()},
     * meaning that the operation should not be retried.
     */
    BackOff STOP_BACKOFF =
        new BackOff() {
  
          @Override
          public void reset() {}
  
          @Override
          public long nextBackOffMillis() {
            return STOP;
          }
        };
  }
  