| 1 | /* |
| 2 | * Copyright 2006-2007 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package org.springframework.batch.retry.policy; |
| 18 | |
| 19 | import java.util.HashSet; |
| 20 | import java.util.Iterator; |
| 21 | import java.util.Set; |
| 22 | |
| 23 | import org.springframework.batch.retry.RetryContext; |
| 24 | import org.springframework.batch.retry.RetryPolicy; |
| 25 | |
| 26 | /** |
| 27 | * Base class for stateful retry policies: those that operate in the context of |
| 28 | * a callback that is called once per retry execution (usually to enforce that |
| 29 | * it is only called once per transaction). Stateful policies need to remember |
| 30 | * the context for the operation that failed (e.g. the data item that was being |
| 31 | * processed), and decide based on its history what to do in the current |
| 32 | * context. For example: the retry operation includes receiving a message, and |
| 33 | * we need it to roll back and be re-delivered so that we can have another crack |
| 34 | * at it. |
| 35 | * |
| 36 | * @see RetryPolicy#handleRetryExhausted(RetryContext) |
| 37 | * @see AbstractStatelessRetryPolicy |
| 38 | * |
| 39 | * @author Dave Syer |
| 40 | * |
| 41 | */ |
| 42 | public abstract class AbstractStatefulRetryPolicy implements RetryPolicy { |
| 43 | |
| 44 | private volatile Set recoverableExceptionClasses = new HashSet(); |
| 45 | |
| 46 | protected RetryContextCache retryContextCache = new MapRetryContextCache(); |
| 47 | |
| 48 | /** |
| 49 | * Optional setter for the retry context cache. The default value is a |
| 50 | * {@link MapRetryContextCache}. |
| 51 | * |
| 52 | * @param retryContextCache |
| 53 | */ |
| 54 | public void setRetryContextCache(RetryContextCache retryContextCache) { |
| 55 | this.retryContextCache = retryContextCache; |
| 56 | } |
| 57 | |
| 58 | /** |
| 59 | * Return null. Subclasses should provide a recovery path if possible. |
| 60 | * |
| 61 | * @see org.springframework.batch.retry.RetryPolicy#handleRetryExhausted(org.springframework.batch.retry.RetryContext) |
| 62 | */ |
| 63 | public Object handleRetryExhausted(RetryContext context) throws Exception { |
| 64 | return null; |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * For a stateful policy the default is to always rethrow. This is the |
| 69 | * cautious approach: we assume that the failed processing may have written |
| 70 | * data to a transactional resource, so we rethrow and force a rollback. Any |
| 71 | * recovery path that may be available has to be taken on the next attempt, |
| 72 | * before any processing has taken place. |
| 73 | * |
| 74 | * @return true unless the last exception registered was recoverable. |
| 75 | */ |
| 76 | public boolean shouldRethrow(RetryContext context) { |
| 77 | return !recoverForException(context.getLastThrowable()); |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * Set the recoverable exceptions. Any exception on the list, or subclasses |
| 82 | * thereof, will be recoverable. If it is encountered in a retry block it |
| 83 | * will not be rethrown. Others will be rethrown. The recovery action (if |
| 84 | * any) is left to subclasses - normally they would override |
| 85 | * {@link #handleRetryExhausted(RetryContext)}. |
| 86 | * |
| 87 | * @param retryableExceptionClasses defaults to {@link Exception}. |
| 88 | */ |
| 89 | public final void setRecoverableExceptionClasses(Class[] retryableExceptionClasses) { |
| 90 | Set temp = new HashSet(); |
| 91 | for (int i = 0; i < retryableExceptionClasses.length; i++) { |
| 92 | addRecoverableExceptionClass(retryableExceptionClasses[i], temp); |
| 93 | } |
| 94 | this.recoverableExceptionClasses = temp; |
| 95 | } |
| 96 | |
| 97 | private void addRecoverableExceptionClass(Class retryableExceptionClass, Set set) { |
| 98 | if (!Throwable.class.isAssignableFrom(retryableExceptionClass)) { |
| 99 | throw new IllegalArgumentException("Class '" + retryableExceptionClass.getName() |
| 100 | + "' is not a subtype of Throwable."); |
| 101 | } |
| 102 | set.add(retryableExceptionClass); |
| 103 | } |
| 104 | |
| 105 | protected boolean recoverForException(Throwable ex) { |
| 106 | |
| 107 | // Default is false (but this shouldn't really happen in practice - |
| 108 | // maybe in tests): |
| 109 | if (ex == null) { |
| 110 | return false; |
| 111 | } |
| 112 | |
| 113 | Class exceptionClass = ex.getClass(); |
| 114 | if (recoverableExceptionClasses.contains(exceptionClass)) { |
| 115 | return true; |
| 116 | } |
| 117 | |
| 118 | // check for subclasses |
| 119 | for (Iterator iterator = recoverableExceptionClasses.iterator(); iterator.hasNext();) { |
| 120 | Class cls = (Class) iterator.next(); |
| 121 | if (cls.isAssignableFrom(exceptionClass)) { |
| 122 | addRecoverableExceptionClass(exceptionClass, this.recoverableExceptionClasses); |
| 123 | return true; |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | return false; |
| 128 | } |
| 129 | |
| 130 | } |