| 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 | package org.springframework.batch.item.database; |
| 17 | |
| 18 | import java.util.HashSet; |
| 19 | import java.util.Set; |
| 20 | |
| 21 | import org.springframework.batch.item.ClearFailedException; |
| 22 | import org.springframework.batch.item.FlushFailedException; |
| 23 | import org.springframework.batch.item.ItemWriter; |
| 24 | import org.springframework.batch.repeat.RepeatContext; |
| 25 | import org.springframework.batch.repeat.support.RepeatSynchronizationManager; |
| 26 | import org.springframework.transaction.support.TransactionSynchronizationManager; |
| 27 | import org.springframework.util.Assert; |
| 28 | |
| 29 | /** |
| 30 | * Stores items in transactional resource and flushes aggressively in case of |
| 31 | * failure. This is useful for batch update writers which need to identify the |
| 32 | * failed item after failed flush. |
| 33 | * |
| 34 | * @see BatchSqlUpdateItemWriter |
| 35 | * @see HibernateAwareItemWriter |
| 36 | * |
| 37 | * @author Dave Syer |
| 38 | * @author Robert Kasanicky |
| 39 | */ |
| 40 | public abstract class AbstractTransactionalResourceItemWriter implements ItemWriter { |
| 41 | |
| 42 | private Set failed = new HashSet(); |
| 43 | |
| 44 | /** |
| 45 | * Flushing delegated to subclass surrounded by binding and unbinding of |
| 46 | * transactional resources. |
| 47 | * |
| 48 | * @see org.springframework.batch.item.ItemWriter#flush() |
| 49 | */ |
| 50 | public void flush() throws FlushFailedException { |
| 51 | bindTransactionResources(); |
| 52 | try { |
| 53 | doFlush(); |
| 54 | } |
| 55 | catch (RuntimeException e) { |
| 56 | synchronized (failed) { |
| 57 | failed.addAll(getProcessed()); |
| 58 | } |
| 59 | // This used to contain a call to onError, however, I think this |
| 60 | // should be handled within the step. |
| 61 | throw e; |
| 62 | } |
| 63 | finally { |
| 64 | unbindTransactionResources(); |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | /** |
| 69 | * Delegate to subclass to actually do the writing, but flushes aggressively |
| 70 | * if the item was previously part of a failed chunk. |
| 71 | * |
| 72 | * @throws Exception |
| 73 | * |
| 74 | * @see org.springframework.batch.item.ItemWriter#write(Object) |
| 75 | */ |
| 76 | public void write(Object output) throws Exception { |
| 77 | bindTransactionResources(); |
| 78 | getProcessed().add(output); |
| 79 | doWrite(output); |
| 80 | flushIfNecessary(output); |
| 81 | } |
| 82 | |
| 83 | private void flushIfNecessary(Object output) { |
| 84 | boolean flush; |
| 85 | synchronized (failed) { |
| 86 | flush = failed.contains(output); |
| 87 | } |
| 88 | if (flush) { |
| 89 | // Force early completion to commit aggressively if we encounter a |
| 90 | // failed item (from a failed chunk but we don't know which one was |
| 91 | // the problem). |
| 92 | RepeatSynchronizationManager.setCompleteOnly(); |
| 93 | // Flush now, so that if there is a failure this record can be |
| 94 | // skipped. |
| 95 | flush(); |
| 96 | } |
| 97 | |
| 98 | } |
| 99 | |
| 100 | /** |
| 101 | * Delegate to subclass and unbind transactional resources, effectively |
| 102 | * clearing the item buffer. |
| 103 | */ |
| 104 | public void clear() throws ClearFailedException { |
| 105 | try { |
| 106 | doClear(); |
| 107 | } |
| 108 | finally { |
| 109 | unbindTransactionResources(); |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | /** |
| 114 | * Callback method of {@link #flush()}. |
| 115 | */ |
| 116 | protected abstract void doFlush() throws FlushFailedException; |
| 117 | |
| 118 | /** |
| 119 | * Callback method of {@link #clear()}. |
| 120 | */ |
| 121 | protected abstract void doClear() throws ClearFailedException; |
| 122 | |
| 123 | /** |
| 124 | * Callback method of {@link #write(Object)}. |
| 125 | */ |
| 126 | protected abstract void doWrite(Object output) throws Exception; |
| 127 | |
| 128 | /** |
| 129 | * @return Key for items processed in the current transaction |
| 130 | * {@link RepeatContext}. |
| 131 | */ |
| 132 | protected abstract String getResourceKey(); |
| 133 | |
| 134 | /** |
| 135 | * Set up the {@link RepeatContext} as a transaction resource. |
| 136 | * |
| 137 | * @param context the context to set |
| 138 | */ |
| 139 | private void bindTransactionResources() { |
| 140 | if (TransactionSynchronizationManager.hasResource(getResourceKey())) { |
| 141 | return; |
| 142 | } |
| 143 | TransactionSynchronizationManager.bindResource(getResourceKey(), new HashSet()); |
| 144 | } |
| 145 | |
| 146 | /** |
| 147 | * Remove the transaction resource associated with this context. |
| 148 | */ |
| 149 | private void unbindTransactionResources() { |
| 150 | if (!TransactionSynchronizationManager.hasResource(getResourceKey())) { |
| 151 | return; |
| 152 | } |
| 153 | TransactionSynchronizationManager.unbindResource(getResourceKey()); |
| 154 | } |
| 155 | |
| 156 | /** |
| 157 | * Accessor for the list of processed items in this transaction. |
| 158 | * |
| 159 | * @return the processed |
| 160 | */ |
| 161 | protected Set getProcessed() { |
| 162 | Assert.state(TransactionSynchronizationManager.hasResource(getResourceKey()), |
| 163 | "Processed items not bound to transaction."); |
| 164 | Set processed = (Set) TransactionSynchronizationManager.getResource(getResourceKey()); |
| 165 | return processed; |
| 166 | } |
| 167 | } |