| 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.HashMap; |
| 20 | import java.util.Iterator; |
| 21 | import java.util.Map; |
| 22 | |
| 23 | import org.springframework.batch.retry.RetryCallback; |
| 24 | import org.springframework.batch.retry.RetryContext; |
| 25 | import org.springframework.batch.retry.RetryPolicy; |
| 26 | import org.springframework.batch.retry.TerminatedRetryException; |
| 27 | import org.springframework.batch.retry.context.RetryContextSupport; |
| 28 | import org.springframework.batch.support.ExceptionClassifier; |
| 29 | import org.springframework.batch.support.ExceptionClassifierSupport; |
| 30 | import org.springframework.util.Assert; |
| 31 | |
| 32 | /** |
| 33 | * A {@link RetryPolicy} that dynamically adapts to one of a set of injected |
| 34 | * policies according to the value of the latest exception. |
| 35 | * |
| 36 | * @author Dave Syer |
| 37 | * |
| 38 | */ |
| 39 | public class ExceptionClassifierRetryPolicy extends AbstractStatelessRetryPolicy { |
| 40 | |
| 41 | private ExceptionClassifier exceptionClassifier = new ExceptionClassifierSupport(); |
| 42 | |
| 43 | private Map policyMap = new HashMap(); |
| 44 | |
| 45 | public ExceptionClassifierRetryPolicy() { |
| 46 | policyMap.put(ExceptionClassifierSupport.DEFAULT, new NeverRetryPolicy()); |
| 47 | } |
| 48 | |
| 49 | /** |
| 50 | * Setter for policy map. This property should not be changed dynamically - |
| 51 | * set it once, e.g. in configuration, and then don't change it during a |
| 52 | * running application. |
| 53 | * |
| 54 | * @param policyMap a map of String to {@link RetryPolicy} that will be |
| 55 | * applied to the result of the {@link ExceptionClassifier} to locate a |
| 56 | * policy. |
| 57 | */ |
| 58 | public void setPolicyMap(Map policyMap) { |
| 59 | this.policyMap = policyMap; |
| 60 | } |
| 61 | |
| 62 | /** |
| 63 | * Setter for an exception classifier. The classifier is responsible for |
| 64 | * translating exceptions to keys in the policy map. |
| 65 | * |
| 66 | * @param exceptionClassifier |
| 67 | */ |
| 68 | public void setExceptionClassifier(ExceptionClassifier exceptionClassifier) { |
| 69 | this.exceptionClassifier = exceptionClassifier; |
| 70 | } |
| 71 | |
| 72 | /** |
| 73 | * Delegate to the policy currently activated in the context. |
| 74 | * |
| 75 | * @see org.springframework.batch.retry.RetryPolicy#canRetry(org.springframework.batch.retry.RetryContext) |
| 76 | */ |
| 77 | public boolean canRetry(RetryContext context) { |
| 78 | RetryPolicy policy = (RetryPolicy) context; |
| 79 | return policy.canRetry(context); |
| 80 | } |
| 81 | |
| 82 | /** |
| 83 | * Delegate to the policy currently activated in the context. |
| 84 | * |
| 85 | * @see org.springframework.batch.retry.RetryPolicy#close(org.springframework.batch.retry.RetryContext) |
| 86 | */ |
| 87 | public void close(RetryContext context) { |
| 88 | RetryPolicy policy = (RetryPolicy) context; |
| 89 | policy.close(context); |
| 90 | } |
| 91 | |
| 92 | /** |
| 93 | * Create an active context that proxies a retry policy by chosing a target |
| 94 | * from the policy map. |
| 95 | * |
| 96 | * @see org.springframework.batch.retry.RetryPolicy#open(org.springframework.batch.retry.RetryCallback, RetryContext) |
| 97 | */ |
| 98 | public RetryContext open(RetryCallback callback, RetryContext parent) { |
| 99 | return new ExceptionClassifierRetryContext(parent, exceptionClassifier).open(callback, parent); |
| 100 | } |
| 101 | |
| 102 | /** |
| 103 | * Delegate to the policy currently activated in the context. |
| 104 | * |
| 105 | * @see org.springframework.batch.retry.RetryPolicy#registerThrowable(org.springframework.batch.retry.RetryContext, |
| 106 | * java.lang.Throwable) |
| 107 | */ |
| 108 | public void registerThrowable(RetryContext context, Throwable throwable) throws TerminatedRetryException { |
| 109 | RetryPolicy policy = (RetryPolicy) context; |
| 110 | policy.registerThrowable(context, throwable); |
| 111 | ((RetryContextSupport) context).registerThrowable(throwable); |
| 112 | } |
| 113 | |
| 114 | private class ExceptionClassifierRetryContext extends RetryContextSupport implements RetryPolicy { |
| 115 | |
| 116 | private ExceptionClassifier exceptionClassifier; |
| 117 | |
| 118 | // Dynamic: depends on the latest exception: |
| 119 | RetryPolicy policy; |
| 120 | |
| 121 | // Dynamic: depends on the policy: |
| 122 | RetryContext context; |
| 123 | |
| 124 | // The same for the life of the context: |
| 125 | RetryCallback callback; |
| 126 | |
| 127 | Map contexts = new HashMap(); |
| 128 | |
| 129 | public ExceptionClassifierRetryContext(RetryContext parent, ExceptionClassifier exceptionClassifier) { |
| 130 | super(parent); |
| 131 | this.exceptionClassifier = exceptionClassifier; |
| 132 | Object key = exceptionClassifier.getDefault(); |
| 133 | policy = getPolicy(key); |
| 134 | Assert.notNull(policy, "Could not locate default policy: key=[" + key + "]."); |
| 135 | } |
| 136 | |
| 137 | public boolean canRetry(RetryContext context) { |
| 138 | return policy.canRetry(this.context); |
| 139 | } |
| 140 | |
| 141 | public boolean shouldRethrow(RetryContext context) { |
| 142 | return policy.shouldRethrow(context); |
| 143 | } |
| 144 | |
| 145 | public void close(RetryContext context) { |
| 146 | // Only close those policies that have been used (opened): |
| 147 | for (Iterator iter = contexts.keySet().iterator(); iter.hasNext();) { |
| 148 | RetryPolicy policy = (RetryPolicy) iter.next(); |
| 149 | policy.close(getContext(policy)); |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | public RetryContext open(RetryCallback callback, RetryContext parent) { |
| 154 | this.callback = callback; |
| 155 | return this; |
| 156 | } |
| 157 | |
| 158 | public void registerThrowable(RetryContext context, Throwable throwable) throws TerminatedRetryException { |
| 159 | policy = getPolicy(exceptionClassifier.classify(throwable)); |
| 160 | this.context = getContext(policy); |
| 161 | policy.registerThrowable(this.context, throwable); |
| 162 | } |
| 163 | |
| 164 | private RetryContext getContext(RetryPolicy policy) { |
| 165 | RetryContext context = (RetryContext) contexts.get(policy); |
| 166 | if (context == null) { |
| 167 | context = policy.open(callback, null); |
| 168 | contexts.put(policy, context); |
| 169 | } |
| 170 | return context; |
| 171 | } |
| 172 | |
| 173 | private RetryPolicy getPolicy(Object key) { |
| 174 | RetryPolicy result = (RetryPolicy) policyMap.get(key); |
| 175 | Assert.notNull(result, "Could not locate policy for key=[" + key + "]."); |
| 176 | return result; |
| 177 | } |
| 178 | |
| 179 | public Object handleRetryExhausted(RetryContext context) throws Exception { |
| 180 | // Not called... |
| 181 | throw new UnsupportedOperationException("Not supported - this code should be unreachable."); |
| 182 | } |
| 183 | |
| 184 | } |
| 185 | |
| 186 | } |