1 /** 2 * 3 * Licensed to the Apache Software Foundation (ASF) under one 4 * or more contributor license agreements. See the NOTICE file 5 * distributed with this work for additional information 6 * regarding copyright ownership. The ASF licenses this file 7 * to you under the Apache License, Version 2.0 (the 8 * "License"); you may not use this file except in compliance 9 * with the License. You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, software 14 * distributed under the License is distributed on an "AS IS" BASIS, 15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 16 * See the License for the specific language governing permissions and 17 * limitations under the License. 18 */ 19 20 package org.apache.hadoop.hbase.client; 21 22 import java.io.IOException; 23 24 import org.apache.hadoop.hbase.classification.InterfaceAudience; 25 26 /** 27 * A Callable<T> that will be retried. If {@link #call(int)} invocation throws exceptions, 28 * we will call {@link #throwable(Throwable, boolean)} with whatever the exception was. 29 * @param <T> result class from executing <tt>this</tt> 30 */ 31 @InterfaceAudience.Private 32 public interface RetryingCallable<T> { 33 /** 34 * Prepare by setting up any connections to servers, etc., ahead of {@link #call(int)} invocation. 35 * @param reload Set this to true if need to requery locations 36 * @throws IOException e 37 */ 38 void prepare(final boolean reload) throws IOException; 39 40 /** 41 * Called when {@link #call(int)} throws an exception and we are going to retry; take action to 42 * make it so we succeed on next call (clear caches, do relookup of locations, etc.). 43 * @param t 44 * @param retrying True if we are in retrying mode (we are not in retrying mode when max 45 * retries == 1; we ARE in retrying mode if retries > 1 even when we are the last attempt) 46 */ 47 void throwable(final Throwable t, boolean retrying); 48 49 /** 50 * Computes a result, or throws an exception if unable to do so. 51 * 52 * @param callTimeout - the time available for this call. 0 for infinite. 53 * @return computed result 54 * @throws Exception if unable to compute a result 55 */ 56 T call(int callTimeout) throws Exception; 57 58 /** 59 * @return Some details from the implementation that we would like to add to a terminating 60 * exception; i.e. a fatal exception is being thrown ending retries and we might like to add 61 * more implementation-specific detail on to the exception being thrown. 62 */ 63 String getExceptionMessageAdditionalDetail(); 64 65 /** 66 * @param pause 67 * @param tries 68 * @return Suggestion on how much to sleep between retries 69 */ 70 long sleep(final long pause, final int tries); 71 }