| 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.core.step.item; |
| 17 | |
| 18 | import org.apache.commons.logging.Log; |
| 19 | import org.apache.commons.logging.LogFactory; |
| 20 | import org.springframework.batch.item.ExecutionContext; |
| 21 | import org.springframework.batch.item.ItemReader; |
| 22 | import org.springframework.batch.item.ItemStream; |
| 23 | import org.springframework.batch.item.ItemStreamException; |
| 24 | import org.springframework.batch.item.support.CompositeItemStream; |
| 25 | |
| 26 | /** |
| 27 | * Manage the offset data between the last successful commit and updates made to |
| 28 | * an input chunk. Only works with single threaded steps because it has to use a |
| 29 | * {@link ThreadLocal} to manage the state and co-ordinate between the caller |
| 30 | * and the wrapped {@link ItemStream}. |
| 31 | * |
| 32 | * @author Dave Syer |
| 33 | * @since 2.0 |
| 34 | */ |
| 35 | class ChunkMonitor implements ItemStream { |
| 36 | |
| 37 | private Log logger = LogFactory.getLog(getClass()); |
| 38 | |
| 39 | private boolean streamsRegistered = false; |
| 40 | |
| 41 | public static class ChunkMonitorData { |
| 42 | public int offset; |
| 43 | |
| 44 | public int chunkSize; |
| 45 | |
| 46 | public ChunkMonitorData(int offset, int chunkSize) { |
| 47 | this.offset = offset; |
| 48 | this.chunkSize = chunkSize; |
| 49 | } |
| 50 | } |
| 51 | |
| 52 | private static final String OFFSET = ChunkMonitor.class.getName() + ".OFFSET"; |
| 53 | |
| 54 | private CompositeItemStream stream = new CompositeItemStream(); |
| 55 | |
| 56 | private ThreadLocal<ChunkMonitorData> holder = new ThreadLocal<ChunkMonitorData>(); |
| 57 | |
| 58 | private ItemReader<?> reader; |
| 59 | |
| 60 | /** |
| 61 | * @param stream the stream to set |
| 62 | */ |
| 63 | public void registerItemStream(ItemStream stream) { |
| 64 | streamsRegistered = true; |
| 65 | this.stream.register(stream); |
| 66 | } |
| 67 | |
| 68 | /** |
| 69 | * @param reader the reader to set |
| 70 | */ |
| 71 | public void setItemReader(ItemReader<?> reader) { |
| 72 | this.reader = reader; |
| 73 | } |
| 74 | |
| 75 | public void incrementOffset() { |
| 76 | ChunkMonitorData data = getData(); |
| 77 | data.offset ++; |
| 78 | if (data.offset >= data.chunkSize) { |
| 79 | resetOffset(); |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | public int getOffset() { |
| 84 | return getData().offset; |
| 85 | } |
| 86 | |
| 87 | public void resetOffset() { |
| 88 | getData().offset = 0; |
| 89 | } |
| 90 | |
| 91 | public void setChunkSize(int chunkSize) { |
| 92 | getData().chunkSize = chunkSize; |
| 93 | resetOffset(); |
| 94 | } |
| 95 | |
| 96 | public void close() throws ItemStreamException { |
| 97 | holder.set(null); |
| 98 | if (streamsRegistered) { |
| 99 | stream.close(); |
| 100 | } |
| 101 | } |
| 102 | |
| 103 | public void open(ExecutionContext executionContext) throws ItemStreamException { |
| 104 | if (streamsRegistered) { |
| 105 | stream.open(executionContext); |
| 106 | ChunkMonitorData data = new ChunkMonitorData(executionContext.getInt(OFFSET, 0), 0); |
| 107 | holder.set(data); |
| 108 | if (reader == null) { |
| 109 | logger.warn("No ItemReader set (must be concurrent step), so ignoring offset data."); |
| 110 | return; |
| 111 | } |
| 112 | for (int i = 0; i < data.offset; i++) { |
| 113 | try { |
| 114 | reader.read(); |
| 115 | } |
| 116 | catch (Exception e) { |
| 117 | throw new ItemStreamException("Could not position reader with offset: " + data.offset, e); |
| 118 | } |
| 119 | } |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | public void update(ExecutionContext executionContext) throws ItemStreamException { |
| 124 | if (streamsRegistered) { |
| 125 | ChunkMonitorData data = getData(); |
| 126 | if (data.offset == 0) { |
| 127 | // Only call the underlying update method if we are on a chunk |
| 128 | // boundary |
| 129 | stream.update(executionContext); |
| 130 | } |
| 131 | else { |
| 132 | executionContext.putInt(OFFSET, data.offset); |
| 133 | } |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | private ChunkMonitorData getData() { |
| 138 | ChunkMonitorData data = holder.get(); |
| 139 | if (data==null) { |
| 140 | if (streamsRegistered) { |
| 141 | logger.warn("ItemStream was opened in a different thread. Restart data could be compromised."); |
| 142 | } |
| 143 | data = new ChunkMonitorData(0,0); |
| 144 | holder.set(data); |
| 145 | } |
| 146 | return data; |
| 147 | } |
| 148 | |
| 149 | } |