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.classification.InterfaceAudience;
26 import org.apache.hadoop.classification.InterfaceStability;
27
28 /**
29 * A Callable<T> that will be retried. If {@link #call()} invocation throws exceptions,
30 * we will call {@link #throwable(Throwable, boolean)} with whatever the exception was.
31 * @param <T>
32 */
33 @InterfaceAudience.Public
34 @InterfaceStability.Stable
35 public interface RetryingCallable<T> extends Callable<T> {
36 /**
37 * Prepare by setting up any connections to servers, etc., ahead of {@link #call()} invocation.
38 * @param reload Set this to true if need to requery locations (usually set on second invocation
39 * to {@link #call()} or whatever
40 * @throws IOException e
41 */
42 void prepare(final boolean reload) throws IOException;
43
44 /**
45 * Called when {@link #call()} throws an exception and we are going to retry; take action to
46 * make it so we succeed on next call (clear caches, do relookup of locations, etc.).
47 * @param t
48 * @param retrying True if we are in retrying mode (we are not in retrying mode when max
49 * retries == 1; we ARE in retrying mode if retries > 1 even when we are the last attempt)
50 */
51 void throwable(final Throwable t, boolean retrying);
52
53 /**
54 * @return Some details from the implementation that we would like to add to a terminating
55 * exception; i.e. a fatal exception is being thrown ending retries and we might like to add
56 * more implementation-specific detail on to the exception being thrown.
57 */
58 String getExceptionMessageAdditionalDetail();
59
60 /**
61 * @param pause
62 * @param tries
63 * @return Suggestion on how much to sleep between retries
64 */
65 long sleep(final long pause, final int tries);
66 }