001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.client;
019
020import java.io.IOException;
021import org.apache.yetus.audience.InterfaceAudience;
022
023/**
024 * A Callable<T> that will be retried. If {@link #call(int)} invocation throws exceptions, we
025 * will call {@link #throwable(Throwable, boolean)} with whatever the exception was.
026 * @param <T> result class from executing <tt>this</tt>
027 */
028@InterfaceAudience.Private
029public interface RetryingCallable<T> {
030  /**
031   * Prepare by setting up any connections to servers, etc., ahead of call invocation. TODO: We call
032   * prepare before EVERY call. Seems wrong. FIX!!!!
033   * @param reload Set this to true if need to requery locations
034   * @throws IOException e
035   */
036  void prepare(final boolean reload) throws IOException;
037
038  /**
039   * Called when call throws an exception and we are going to retry; take action to make it so we
040   * succeed on next call (clear caches, do relookup of locations, etc.).
041   * @param t        throwable which was thrown
042   * @param retrying True if we are in retrying mode (we are not in retrying mode when max retries
043   *                 == 1; we ARE in retrying mode if retries &gt; 1 even when we are the last
044   *                 attempt)
045   */
046  void throwable(final Throwable t, boolean retrying);
047
048  /**
049   * Returns Some details from the implementation that we would like to add to a terminating
050   * exception; i.e. a fatal exception is being thrown ending retries and we might like to add more
051   * implementation-specific detail on to the exception being thrown.
052   */
053  String getExceptionMessageAdditionalDetail();
054
055  /**
056   * Sleep and retry.
057   * @param pause time to pause
058   * @param tries amount of tries until till sleep
059   * @return Suggestion on how much to sleep between retries
060   */
061  long sleep(final long pause, final int tries);
062
063  /**
064   * Computes a result, or throws an exception if unable to do so.
065   * @param callTimeout - the time available for this call. 0 for infinite.
066   * @return computed result
067   * @throws Exception if unable to compute a result
068   */
069  T call(int callTimeout) throws Exception;
070}