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.bookkeeper.zookeeper;
  
  import java.util.Arrays;
  import java.util.Random;
  import lombok.extern.slf4j.Slf4j;
  
  /**
   * Backoff time determined based as a multiple of baseBackoffTime.
   * The multiple value depends on retryCount.
   * If the retry schedule exceeds the deadline, we schedule a final attempt exactly at the deadline.
   */
  @Slf4j
  public class ExponentialBackOffWithDeadlinePolicy implements RetryPolicy {
  
      static final int [] RETRY_BACKOFF = {0, 1, 2, 3, 5, 5, 5, 10, 10, 10, 20, 40, 100};
      public static final int JITTER_PERCENT = 10;
      private final Random random;
  
      private final long baseBackoffTime;
      private final long deadline;
      private final int maxRetries;
  
      public ExponentialBackOffWithDeadlinePolicy(long baseBackoffTime, long deadline, int maxRetries) {
          this.baseBackoffTime = baseBackoffTime;
          this.deadline = deadline;
          this.maxRetries = maxRetries;
          this.random = new Random(System.currentTimeMillis());
      }
  
      @Override
      public boolean allowRetry(int retryCount, long elapsedRetryTime) {
          return retryCount <= maxRetries && elapsedRetryTime < deadline;
      }
  
      @Override
      public long nextRetryWaitTime(int retryCount, long elapsedRetryTime) {
          int idx = retryCount;
          if (idx >= RETRY_BACKOFF.length) {
              idx = RETRY_BACKOFF.length - 1;
          }
  
          long waitTime = (baseBackoffTime * RETRY_BACKOFF[idx]);
          long jitter = (random.nextInt(JITTER_PERCENT) * waitTime / 100);
  
          if (elapsedRetryTime + waitTime + jitter > deadline) {
              log.warn("Final retry attempt: {}, timeleft: {}, stacktrace: {}",
                      retryCount, (deadline - elapsedRetryTime), Arrays.toString(Thread.currentThread().getStackTrace()));
              return deadline - elapsedRetryTime;
          }
  
          return waitTime + jitter;
      }
  }