| 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 org.apache.commons.logging.Log; |
| 20 | import org.apache.commons.logging.LogFactory; |
| 21 | import org.springframework.batch.repeat.support.RepeatSynchronizationManager; |
| 22 | import org.springframework.batch.retry.ExhaustedRetryException; |
| 23 | import org.springframework.batch.retry.RecoveryCallback; |
| 24 | import org.springframework.batch.retry.RetryCallback; |
| 25 | import org.springframework.batch.retry.RetryContext; |
| 26 | import org.springframework.batch.retry.RetryException; |
| 27 | import org.springframework.batch.retry.RetryPolicy; |
| 28 | import org.springframework.batch.retry.TerminatedRetryException; |
| 29 | import org.springframework.batch.retry.callback.RecoveryRetryCallback; |
| 30 | import org.springframework.batch.retry.context.RetryContextSupport; |
| 31 | import org.springframework.util.Assert; |
| 32 | |
| 33 | /** |
| 34 | * A {@link RetryPolicy} that detects an {@link RecoveryRetryCallback} when it |
| 35 | * opens a new context, and uses it to make sure the item is in place for later |
| 36 | * decisions about how to retry or backoff. The callback should be an instance |
| 37 | * of {@link RecoveryRetryCallback} otherwise an exception will be thrown when |
| 38 | * the context is created. |
| 39 | * |
| 40 | * @author Dave Syer |
| 41 | * |
| 42 | */ |
| 43 | public class RecoveryCallbackRetryPolicy extends AbstractStatefulRetryPolicy { |
| 44 | |
| 45 | protected Log logger = LogFactory.getLog(getClass()); |
| 46 | |
| 47 | public static final String EXHAUSTED = RecoveryCallbackRetryPolicy.class.getName() + ".EXHAUSTED"; |
| 48 | |
| 49 | private RetryPolicy delegate; |
| 50 | |
| 51 | /** |
| 52 | * Convenience constructor to set delegate on init. |
| 53 | * |
| 54 | * @param delegate |
| 55 | */ |
| 56 | public RecoveryCallbackRetryPolicy(RetryPolicy delegate) { |
| 57 | super(); |
| 58 | this.delegate = delegate; |
| 59 | } |
| 60 | |
| 61 | /** |
| 62 | * Default constructor. Creates a new {@link SimpleRetryPolicy} for the |
| 63 | * delegate. |
| 64 | */ |
| 65 | public RecoveryCallbackRetryPolicy() { |
| 66 | this(new SimpleRetryPolicy()); |
| 67 | } |
| 68 | |
| 69 | /** |
| 70 | * Setter for delegate. |
| 71 | * |
| 72 | * @param delegate |
| 73 | */ |
| 74 | public void setDelegate(RetryPolicy delegate) { |
| 75 | this.delegate = delegate; |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * Check the history of this item, and if it has reached the retry limit, |
| 80 | * then return false. |
| 81 | * |
| 82 | * @see org.springframework.batch.retry.RetryPolicy#canRetry(org.springframework.batch.retry.RetryContext) |
| 83 | */ |
| 84 | public boolean canRetry(RetryContext context) { |
| 85 | return ((RetryPolicy) context).canRetry(context); |
| 86 | } |
| 87 | |
| 88 | /** |
| 89 | * Delegates to the delegate context. |
| 90 | * |
| 91 | * @see org.springframework.batch.retry.RetryPolicy#close(org.springframework.batch.retry.RetryContext) |
| 92 | */ |
| 93 | public void close(RetryContext context) { |
| 94 | ((RetryPolicy) context).close(context); |
| 95 | } |
| 96 | |
| 97 | /** |
| 98 | * Create a new context for the execution of the callback, which must be an |
| 99 | * instance of {@link RecoveryRetryCallback}. |
| 100 | * |
| 101 | * @see org.springframework.batch.retry.RetryPolicy#open(org.springframework.batch.retry.RetryCallback, |
| 102 | * RetryContext) |
| 103 | * |
| 104 | * @throws IllegalStateException if the callback is not of the required |
| 105 | * type. |
| 106 | */ |
| 107 | public RetryContext open(RetryCallback callback, RetryContext parent) { |
| 108 | Assert.state(callback instanceof RecoveryRetryCallback, "Callback must be RecoveryRetryCallback"); |
| 109 | RecoveryCallbackRetryContext context = new RecoveryCallbackRetryContext((RecoveryRetryCallback) callback, parent); |
| 110 | context.open(callback, null); |
| 111 | return context; |
| 112 | } |
| 113 | |
| 114 | /** |
| 115 | * If {@link #canRetry(RetryContext)} is false then take remedial action (if |
| 116 | * implemented by subclasses), and remove the current item from the history. |
| 117 | * |
| 118 | * @see org.springframework.batch.retry.RetryPolicy#registerThrowable(org.springframework.batch.retry.RetryContext, |
| 119 | * java.lang.Throwable) |
| 120 | */ |
| 121 | public void registerThrowable(RetryContext context, Throwable throwable) throws TerminatedRetryException { |
| 122 | ((RetryPolicy) context).registerThrowable(context, throwable); |
| 123 | // The throwable is stored in the delegate context. |
| 124 | } |
| 125 | |
| 126 | /** |
| 127 | * Call recovery path (if any) and clean up context history. |
| 128 | * |
| 129 | * @see org.springframework.batch.retry.policy.AbstractStatefulRetryPolicy#handleRetryExhausted(org.springframework.batch.retry.RetryContext) |
| 130 | */ |
| 131 | public Object handleRetryExhausted(RetryContext context) throws ExhaustedRetryException { |
| 132 | return ((RetryPolicy) context).handleRetryExhausted(context); |
| 133 | } |
| 134 | |
| 135 | private class RecoveryCallbackRetryContext extends RetryContextSupport implements RetryPolicy { |
| 136 | |
| 137 | final private Object key; |
| 138 | |
| 139 | final private int initialHashCode; |
| 140 | |
| 141 | // The delegate context... |
| 142 | private RetryContext delegateContext; |
| 143 | |
| 144 | final private RecoveryCallback recoverer; |
| 145 | |
| 146 | final private boolean forceRefresh; |
| 147 | |
| 148 | public RecoveryCallbackRetryContext(RecoveryRetryCallback callback, RetryContext parent) { |
| 149 | super(parent); |
| 150 | this.recoverer = callback.getRecoveryCallback(); |
| 151 | this.key = callback.getKey(); |
| 152 | this.forceRefresh = callback.isForceRefresh(); |
| 153 | this.initialHashCode = key.hashCode(); |
| 154 | } |
| 155 | |
| 156 | public boolean canRetry(RetryContext context) { |
| 157 | return delegate.canRetry(this.delegateContext); |
| 158 | } |
| 159 | |
| 160 | public void close(RetryContext context) { |
| 161 | delegate.close(this.delegateContext); |
| 162 | } |
| 163 | |
| 164 | public RetryContext open(RetryCallback callback, RetryContext parent) { |
| 165 | if (forceRefresh) { |
| 166 | // Avoid a cache hit if the caller tells us this is a fresh item |
| 167 | this.delegateContext = delegate.open(callback, null); |
| 168 | } |
| 169 | else if (retryContextCache.containsKey(key)) { |
| 170 | this.delegateContext = retryContextCache.get(key); |
| 171 | if (this.delegateContext == null) { |
| 172 | throw new RetryException("Inconsistent state for failed item: no history found. " |
| 173 | + "Consider whether equals() or hashCode() for the item might be inconsistent, " |
| 174 | + "or if you need to supply a better ItemKeyGenerator"); |
| 175 | } |
| 176 | } |
| 177 | else { |
| 178 | // Only create a new context if we don't know the history of |
| 179 | // this item: |
| 180 | this.delegateContext = delegate.open(callback, null); |
| 181 | } |
| 182 | // The return value shouldn't be used... |
| 183 | return null; |
| 184 | } |
| 185 | |
| 186 | public void registerThrowable(RetryContext context, Throwable throwable) throws TerminatedRetryException { |
| 187 | // TODO: this comparison assumes that hashCode is the limiting |
| 188 | // factor. Actually the cache should be able to decide for us. |
| 189 | if (this.initialHashCode != key.hashCode()) { |
| 190 | throw new RetryException("Inconsistent state for failed item key: hashCode has changed. " |
| 191 | + "Consider whether equals() or hashCode() for the item might be inconsistent, " |
| 192 | + "or if you need to supply a better ItemKeyGenerator"); |
| 193 | } |
| 194 | retryContextCache.put(key, this.delegateContext); |
| 195 | delegate.registerThrowable(this.delegateContext, throwable); |
| 196 | } |
| 197 | |
| 198 | public boolean shouldRethrow(RetryContext context) { |
| 199 | // Not called... |
| 200 | throw new UnsupportedOperationException("Not supported - this code should be unreachable."); |
| 201 | } |
| 202 | |
| 203 | public Object handleRetryExhausted(RetryContext context) throws ExhaustedRetryException { |
| 204 | // If there is no going back, then we can remove the history |
| 205 | retryContextCache.remove(key); |
| 206 | RepeatSynchronizationManager.setCompleteOnly(); |
| 207 | if (recoverer != null) { |
| 208 | return recoverer.recover(context); |
| 209 | } |
| 210 | logger.info("No recovery callback provided. Returning null from recovery step."); |
| 211 | // Don't want to call the delegate here - it would throw an exception |
| 212 | return null; |
| 213 | } |
| 214 | |
| 215 | public Throwable getLastThrowable() { |
| 216 | return delegateContext.getLastThrowable(); |
| 217 | } |
| 218 | |
| 219 | public int getRetryCount() { |
| 220 | return delegateContext.getRetryCount(); |
| 221 | } |
| 222 | |
| 223 | } |
| 224 | |
| 225 | } |