net.sf.ehcache.writer.writebehind.CoalesceKeysFilter Maven / Gradle / Ivy
/**
* Copyright 2003-2010 Terracotta, Inc.
*
* 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
*
* http://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 net.sf.ehcache.writer.writebehind;
import net.sf.ehcache.writer.writebehind.operations.KeyBasedOperation;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Filters the operations by only retaining the latest operations for a given key.
*
* @author Geert Bevin
* @version $Id: CoalesceKeysFilter.java 2154 2010-04-06 02:45:52Z cdennis $
*/
public class CoalesceKeysFilter implements OperationsFilter {
/**
* {@inheritDoc}
*/
public void filter(List operations, OperationConverter converter) {
final Map mostRecent = new HashMap();
final List operationsToRemove = new ArrayList();
// not using an iterator on purpose since the ehcache express types don't support it
for (int i = 0; i < operations.size(); i++) {
Object operation = operations.get(i);
KeyBasedOperation keyBasedOperation = converter.convert(operation);
if (!mostRecent.containsKey(keyBasedOperation.getKey())) {
mostRecent.put(keyBasedOperation.getKey(), operation);
} else {
Object previousOperation = mostRecent.get(keyBasedOperation.getKey());
KeyBasedOperation keyBasedPreviousOperation = converter.convert(previousOperation);
if (keyBasedPreviousOperation.getCreationTime() > keyBasedOperation.getCreationTime()) {
operationsToRemove.add(operation);
} else {
operationsToRemove.add(previousOperation);
mostRecent.put(keyBasedOperation.getKey(), operation);
}
}
}
// not using removeAll on purpose since the ehcache express types don't support it
for (Object operation : operationsToRemove) {
operations.remove(operation);
}
}
}