| 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.repeat.policy; |
| 18 | |
| 19 | import org.springframework.batch.repeat.RepeatContext; |
| 20 | import org.springframework.batch.repeat.context.RepeatContextCounter; |
| 21 | import org.springframework.batch.repeat.context.RepeatContextSupport; |
| 22 | |
| 23 | /** |
| 24 | * Abstract base class for policies that need to count the number of occurrences |
| 25 | * of some event (e.g. an exception type in the context), and terminate based on |
| 26 | * a limit for the counter. The value of the counter can be stored between |
| 27 | * batches in a nested context, so that the termination decision is based on the |
| 28 | * aggregate of a number of sibling batches. |
| 29 | * |
| 30 | * @author Dave Syer |
| 31 | * |
| 32 | */ |
| 33 | public abstract class CountingCompletionPolicy extends DefaultResultCompletionPolicy { |
| 34 | |
| 35 | /** |
| 36 | * Session key for global counter. |
| 37 | */ |
| 38 | public static final String COUNT = CountingCompletionPolicy.class.getName() + ".COUNT"; |
| 39 | |
| 40 | private boolean useParent = false; |
| 41 | |
| 42 | private int maxCount = 0; |
| 43 | |
| 44 | /** |
| 45 | * Flag to indicate whether the count is at the level of the parent context, |
| 46 | * or just local to the context. If true then the count is aggregated among |
| 47 | * siblings in a nested batch. |
| 48 | * |
| 49 | * @param useParent whether to use the parent context to cache the total |
| 50 | * count. Default value is false. |
| 51 | */ |
| 52 | public void setUseParent(boolean useParent) { |
| 53 | this.useParent = useParent; |
| 54 | } |
| 55 | |
| 56 | /** |
| 57 | * Setter for maximum value of count before termination. |
| 58 | * |
| 59 | * @param maxCount the maximum number of counts before termination. Default |
| 60 | * 0 so termination is immediate. |
| 61 | */ |
| 62 | public void setMaxCount(int maxCount) { |
| 63 | this.maxCount = maxCount; |
| 64 | } |
| 65 | |
| 66 | /** |
| 67 | * Extension point for subclasses. Obtain the value of the count in the |
| 68 | * current context. Subclasses can count the number of attempts or |
| 69 | * violations and store the result in their context. This policy base class |
| 70 | * will take care of the termination contract and aggregating at the level |
| 71 | * of the session if required. |
| 72 | * |
| 73 | * @param context the current context, specific to the subclass. |
| 74 | * @return the value of the counter in the context. |
| 75 | */ |
| 76 | protected abstract int getCount(RepeatContext context); |
| 77 | |
| 78 | /** |
| 79 | * Extension point for subclasses. Inspect the context and update the state |
| 80 | * of a counter in whatever way is appropriate. This will be added to the |
| 81 | * session-level counter if {@link #setUseParent(boolean)} is true. |
| 82 | * |
| 83 | * @param context the current context. |
| 84 | * |
| 85 | * @return the change in the value of the counter (default 0). |
| 86 | */ |
| 87 | protected int doUpdate(RepeatContext context) { |
| 88 | return 0; |
| 89 | } |
| 90 | |
| 91 | /* |
| 92 | * (non-Javadoc) |
| 93 | * @see org.springframework.batch.repeat.policy.CompletionPolicySupport#isComplete(org.springframework.batch.repeat.BatchContext) |
| 94 | */ |
| 95 | final public boolean isComplete(RepeatContext context) { |
| 96 | int count = ((CountingBatchContext) context).getCounter().getCount(); |
| 97 | return count >= maxCount; |
| 98 | } |
| 99 | |
| 100 | /* |
| 101 | * (non-Javadoc) |
| 102 | * @see org.springframework.batch.repeat.policy.CompletionPolicySupport#start(org.springframework.batch.repeat.BatchContext) |
| 103 | */ |
| 104 | public RepeatContext start(RepeatContext parent) { |
| 105 | return new CountingBatchContext(parent); |
| 106 | } |
| 107 | |
| 108 | /* |
| 109 | * (non-Javadoc) |
| 110 | * @see org.springframework.batch.repeat.policy.CompletionPolicySupport#update(org.springframework.batch.repeat.BatchContext) |
| 111 | */ |
| 112 | final public void update(RepeatContext context) { |
| 113 | super.update(context); |
| 114 | int delta = doUpdate(context); |
| 115 | ((CountingBatchContext) context).getCounter().increment(delta); |
| 116 | } |
| 117 | |
| 118 | protected class CountingBatchContext extends RepeatContextSupport { |
| 119 | |
| 120 | RepeatContextCounter counter; |
| 121 | |
| 122 | public CountingBatchContext(RepeatContext parent) { |
| 123 | super(parent); |
| 124 | counter = new RepeatContextCounter(this, COUNT, useParent); |
| 125 | } |
| 126 | |
| 127 | public RepeatContextCounter getCounter() { |
| 128 | return counter; |
| 129 | } |
| 130 | |
| 131 | } |
| 132 | } |