org.springframework.batch.repeat.policy.CountingCompletionPolicy Maven / Gradle / Ivy
/*
* Copyright 2006-2007 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.batch.repeat.policy;
import org.springframework.batch.repeat.RepeatContext;
import org.springframework.batch.repeat.context.RepeatContextCounter;
import org.springframework.batch.repeat.context.RepeatContextSupport;
/**
* Abstract base class for policies that need to count the number of occurrences
* of some event (e.g. an exception type in the context), and terminate based on
* a limit for the counter. The value of the counter can be stored between
* batches in a nested context, so that the termination decision is based on the
* aggregate of a number of sibling batches.
*
* @author Dave Syer
*
*/
public abstract class CountingCompletionPolicy extends DefaultResultCompletionPolicy {
/**
* Session key for global counter.
*/
public static final String COUNT = CountingCompletionPolicy.class.getName() + ".COUNT";
private boolean useParent = false;
private int maxCount = 0;
/**
* Flag to indicate whether the count is at the level of the parent context,
* or just local to the context. If true then the count is aggregated among
* siblings in a nested batch.
*
* @param useParent whether to use the parent context to cache the total
* count. Default value is false.
*/
public void setUseParent(boolean useParent) {
this.useParent = useParent;
}
/**
* Setter for maximum value of count before termination.
*
* @param maxCount the maximum number of counts before termination. Default
* 0 so termination is immediate.
*/
public void setMaxCount(int maxCount) {
this.maxCount = maxCount;
}
/**
* Extension point for subclasses. Obtain the value of the count in the
* current context. Subclasses can count the number of attempts or
* violations and store the result in their context. This policy base class
* will take care of the termination contract and aggregating at the level
* of the session if required.
*
* @param context the current context, specific to the subclass.
* @return the value of the counter in the context.
*/
protected abstract int getCount(RepeatContext context);
/**
* Extension point for subclasses. Inspect the context and update the state
* of a counter in whatever way is appropriate. This will be added to the
* session-level counter if {@link #setUseParent(boolean)} is true.
*
* @param context the current context.
*
* @return the change in the value of the counter (default 0).
*/
protected int doUpdate(RepeatContext context) {
return 0;
}
/*
* (non-Javadoc)
* @see org.springframework.batch.repeat.policy.CompletionPolicySupport#isComplete(org.springframework.batch.repeat.BatchContext)
*/
@Override
final public boolean isComplete(RepeatContext context) {
int count = ((CountingBatchContext) context).getCounter().getCount();
return count >= maxCount;
}
/*
* (non-Javadoc)
* @see org.springframework.batch.repeat.policy.CompletionPolicySupport#start(org.springframework.batch.repeat.BatchContext)
*/
@Override
public RepeatContext start(RepeatContext parent) {
return new CountingBatchContext(parent);
}
/*
* (non-Javadoc)
* @see org.springframework.batch.repeat.policy.CompletionPolicySupport#update(org.springframework.batch.repeat.BatchContext)
*/
@Override
final public void update(RepeatContext context) {
super.update(context);
int delta = doUpdate(context);
((CountingBatchContext) context).getCounter().increment(delta);
}
protected class CountingBatchContext extends RepeatContextSupport {
RepeatContextCounter counter;
public CountingBatchContext(RepeatContext parent) {
super(parent);
counter = new RepeatContextCounter(this, COUNT, useParent);
}
public RepeatContextCounter getCounter() {
return counter;
}
}
}