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 import java.util.concurrent.Callable; 24 25 import org.apache.hadoop.hbase.classification.InterfaceAudience; 26 27 /** 28 * A Callable<T> that will be retried. If {@link #call()} invocation throws exceptions, 29 * we will call {@link #throwable(Throwable, boolean)} with whatever the exception was. 30 * @param <T> 31 */ 32 @InterfaceAudience.Private 33 public interface RetryingCallable<T> extends Callable<T> { 34 /** 35 * Prepare by setting up any connections to servers, etc., ahead of {@link #call()} invocation. 36 * @param reload Set this to true if need to requery locations (usually set on second invocation 37 * to {@link #call()} or whatever 38 * @throws IOException e 39 */ 40 void prepare(final boolean reload) throws IOException; 41 42 /** 43 * Called when {@link #call()} throws an exception and we are going to retry; take action to 44 * make it so we succeed on next call (clear caches, do relookup of locations, etc.). 45 * @param t 46 * @param retrying True if we are in retrying mode (we are not in retrying mode when max 47 * retries == 1; we ARE in retrying mode if retries > 1 even when we are the last attempt) 48 */ 49 void throwable(final Throwable t, boolean retrying); 50 51 /** 52 * @return Some details from the implementation that we would like to add to a terminating 53 * exception; i.e. a fatal exception is being thrown ending retries and we might like to add 54 * more implementation-specific detail on to the exception being thrown. 55 */ 56 String getExceptionMessageAdditionalDetail(); 57 58 /** 59 * @param pause 60 * @param tries 61 * @return Suggestion on how much to sleep between retries 62 */ 63 long sleep(final long pause, final int tries); 64 }