| 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.core.step.item; |
| 18 | |
| 19 | import java.util.ArrayList; |
| 20 | import java.util.Collection; |
| 21 | import java.util.Collections; |
| 22 | import java.util.Iterator; |
| 23 | import java.util.List; |
| 24 | |
| 25 | /** |
| 26 | * Encapsulation of a list of items to be processed and possibly a list of |
| 27 | * failed items to be skipped. To mark an item as skipped clients should iterate |
| 28 | * over the chunk using the {@link #iterator()} method, and if there is a |
| 29 | * failure call {@link org.springframework.batch.core.step.item.Chunk.ChunkIterator#remove()} on the iterator. |
| 30 | * The skipped items are then available through the chunk. |
| 31 | * |
| 32 | * @author Dave Syer |
| 33 | * @since 2.0 |
| 34 | */ |
| 35 | public class Chunk<W> implements Iterable<W> { |
| 36 | |
| 37 | private List<W> items = new ArrayList<W>(); |
| 38 | |
| 39 | private List<SkipWrapper<W>> skips = new ArrayList<SkipWrapper<W>>(); |
| 40 | |
| 41 | private List<Exception> errors = new ArrayList<Exception>(); |
| 42 | |
| 43 | private Object userData; |
| 44 | |
| 45 | private boolean end; |
| 46 | |
| 47 | private boolean busy; |
| 48 | |
| 49 | public Chunk() { |
| 50 | this(null, null); |
| 51 | } |
| 52 | |
| 53 | public Chunk(Collection<? extends W> items) { |
| 54 | this(items, null); |
| 55 | } |
| 56 | |
| 57 | public Chunk(Collection<? extends W> items, List<SkipWrapper<W>> skips) { |
| 58 | super(); |
| 59 | if (items != null) { |
| 60 | this.items = new ArrayList<W>(items); |
| 61 | } |
| 62 | if (skips != null) { |
| 63 | this.skips = new ArrayList<SkipWrapper<W>>(skips); |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Add the item to the chunk. |
| 69 | * @param item |
| 70 | */ |
| 71 | public void add(W item) { |
| 72 | items.add(item); |
| 73 | } |
| 74 | |
| 75 | /** |
| 76 | * Clear the items down to signal that we are done. |
| 77 | */ |
| 78 | public void clear() { |
| 79 | items.clear(); |
| 80 | skips.clear(); |
| 81 | userData = null; |
| 82 | } |
| 83 | |
| 84 | /** |
| 85 | * @return a copy of the items to be processed as an unmodifiable list |
| 86 | */ |
| 87 | public List<W> getItems() { |
| 88 | return Collections.unmodifiableList(new ArrayList<W>(items)); |
| 89 | } |
| 90 | |
| 91 | /** |
| 92 | * @return a copy of the skips as an unmodifiable list |
| 93 | */ |
| 94 | public List<SkipWrapper<W>> getSkips() { |
| 95 | return Collections.unmodifiableList(skips); |
| 96 | } |
| 97 | |
| 98 | /** |
| 99 | * @return a copy of the anonymous errros as an unmodifiable list |
| 100 | */ |
| 101 | public List<Exception> getErrors() { |
| 102 | return Collections.unmodifiableList(errors); |
| 103 | } |
| 104 | |
| 105 | /** |
| 106 | * Register an anonymous skip. To skip an individual item, use |
| 107 | * {@link ChunkIterator#remove()}. |
| 108 | * |
| 109 | * @param e the exception that caused the skip |
| 110 | */ |
| 111 | public void skip(Exception e) { |
| 112 | errors.add(e); |
| 113 | } |
| 114 | |
| 115 | /** |
| 116 | * @return true if there are no items in the chunk |
| 117 | */ |
| 118 | public boolean isEmpty() { |
| 119 | return items.isEmpty(); |
| 120 | } |
| 121 | |
| 122 | /** |
| 123 | * Get an unmodifiable iterator for the underlying items. |
| 124 | * @see java.lang.Iterable#iterator() |
| 125 | */ |
| 126 | public ChunkIterator iterator() { |
| 127 | return new ChunkIterator(items); |
| 128 | } |
| 129 | |
| 130 | /** |
| 131 | * @return the number of items (excluding skips) |
| 132 | */ |
| 133 | public int size() { |
| 134 | return items.size(); |
| 135 | } |
| 136 | |
| 137 | /** |
| 138 | * Flag to indicate if the source data is exhausted. |
| 139 | * |
| 140 | * @return true if there is no more data to process |
| 141 | */ |
| 142 | public boolean isEnd() { |
| 143 | return end; |
| 144 | } |
| 145 | |
| 146 | /** |
| 147 | * Set the flag to say that this chunk represents an end of stream (there is |
| 148 | * no more data to process). |
| 149 | */ |
| 150 | public void setEnd() { |
| 151 | this.end = true; |
| 152 | } |
| 153 | |
| 154 | /** |
| 155 | * Query the chunk to see if anyone has registered an interest in keeping a |
| 156 | * reference to it. |
| 157 | * |
| 158 | * @return the busy flag |
| 159 | */ |
| 160 | public boolean isBusy() { |
| 161 | return busy; |
| 162 | } |
| 163 | |
| 164 | /** |
| 165 | * Register an interest in the chunk to prevent it from being cleaned up |
| 166 | * before the flag is reset to false. |
| 167 | * |
| 168 | * @param busy the flag to set |
| 169 | */ |
| 170 | public void setBusy(boolean busy) { |
| 171 | this.busy = busy; |
| 172 | } |
| 173 | |
| 174 | /** |
| 175 | * Clear only the skips list. |
| 176 | */ |
| 177 | public void clearSkips() { |
| 178 | skips.clear(); |
| 179 | } |
| 180 | |
| 181 | public Object getUserData() { |
| 182 | return userData; |
| 183 | } |
| 184 | |
| 185 | public void setUserData(Object userData) { |
| 186 | this.userData = userData; |
| 187 | } |
| 188 | |
| 189 | /* |
| 190 | * (non-Javadoc) |
| 191 | * |
| 192 | * @see java.lang.Object#toString() |
| 193 | */ |
| 194 | @Override |
| 195 | public String toString() { |
| 196 | return String.format("[items=%s, skips=%s]", items, skips); |
| 197 | } |
| 198 | |
| 199 | /** |
| 200 | * Special iterator for a chunk providing the {@link #remove(Exception)} |
| 201 | * method for dynamically removing an item and adding it to the skips. |
| 202 | * |
| 203 | * @author Dave Syer |
| 204 | * |
| 205 | */ |
| 206 | public class ChunkIterator implements Iterator<W> { |
| 207 | |
| 208 | final private Iterator<W> iterator; |
| 209 | |
| 210 | private W next; |
| 211 | |
| 212 | public ChunkIterator(List<W> items) { |
| 213 | iterator = items.iterator(); |
| 214 | } |
| 215 | |
| 216 | public boolean hasNext() { |
| 217 | return iterator.hasNext(); |
| 218 | } |
| 219 | |
| 220 | public W next() { |
| 221 | next = iterator.next(); |
| 222 | return next; |
| 223 | } |
| 224 | |
| 225 | public void remove(Throwable e) { |
| 226 | remove(); |
| 227 | skips.add(new SkipWrapper<W>(next, e)); |
| 228 | } |
| 229 | |
| 230 | public void remove() { |
| 231 | if (next == null) { |
| 232 | if (iterator.hasNext()) { |
| 233 | next = iterator.next(); |
| 234 | } |
| 235 | else { |
| 236 | return; |
| 237 | } |
| 238 | } |
| 239 | iterator.remove(); |
| 240 | } |
| 241 | |
| 242 | @Override |
| 243 | public String toString() { |
| 244 | return String.format("[items=%s, skips=%s]", items, skips); |
| 245 | } |
| 246 | |
| 247 | } |
| 248 | |
| 249 | } |