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.common.security.oauthbearer.internals.secured;
  
  import org.apache.kafka.common.utils.Time;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.util.concurrent.ExecutionException;
  
  /**
   * Retry encapsulates the mechanism to perform a retry and then exponential
   * backoff using provided wait times between attempts.
   *
   * @param <R> Result type
   */
  
  public class Retry<R> {
  
      private static final Logger log = LoggerFactory.getLogger(Retry.class);
  
      private final Time time;
  
      private final long retryBackoffMs;
  
      private final long retryBackoffMaxMs;
  
      public Retry(long retryBackoffMs, long retryBackoffMaxMs) {
          this(Time.SYSTEM, retryBackoffMs, retryBackoffMaxMs);
      }
  
      public Retry(Time time, long retryBackoffMs, long retryBackoffMaxMs) {
          this.time = time;
          this.retryBackoffMs = retryBackoffMs;
          this.retryBackoffMaxMs = retryBackoffMaxMs;
  
          if (this.retryBackoffMs < 0)
              throw new IllegalArgumentException(String.format("retryBackoffMs value (%d) must be non-negative", retryBackoffMs));
  
          if (this.retryBackoffMaxMs < 0)
              throw new IllegalArgumentException(String.format("retryBackoffMaxMs value (%d) must be non-negative", retryBackoffMaxMs));
  
          if (this.retryBackoffMaxMs < this.retryBackoffMs)
              throw new IllegalArgumentException(String.format("retryBackoffMaxMs value (%d) is less than retryBackoffMs value (%d)", retryBackoffMaxMs, retryBackoffMs));
      }
  
      public R execute(Retryable<R> retryable) throws ExecutionException {
          long endMs = time.milliseconds() + retryBackoffMaxMs;
          int currAttempt = 0;
          ExecutionException error = null;
  
          while (time.milliseconds() <= endMs) {
              currAttempt++;
  
              try {
                  return retryable.call();
              } catch (UnretryableException e) {
                  // We've deemed this error to not be worth retrying, so collect the error and
                  // fail immediately.
                  if (error == null)
                      error = new ExecutionException(e);
  
                  break;
              } catch (ExecutionException e) {
                  log.warn("Error during retry attempt {}", currAttempt, e);
  
                  if (error == null)
                      error = e;
  
                  long waitMs = retryBackoffMs * (long) Math.pow(2, currAttempt - 1);
                  long diff = endMs - time.milliseconds();
                  waitMs = Math.min(waitMs, diff);
  
                  if (waitMs <= 0)
                      break;
  
                  String message = String.format("Attempt %d to make call resulted in an error; sleeping %d ms before retrying",
                      currAttempt, waitMs);
                  log.warn(message, e);
  
                  time.sleep(waitMs);
              }
          }
  
          if (error == null)
              // Really shouldn't ever get to here, but...
              error = new ExecutionException(new IllegalStateException("Exhausted all retry attempts but no attempt returned value or encountered exception"));
  
          throw error;
      }
  
  }
  