/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 storm.trident.state;
import storm.trident.operation.CombinerAggregator;
public class CombinerValueUpdater implements ValueUpdater<Object> {
Object arg;
CombinerAggregator agg;
public CombinerValueUpdater(CombinerAggregator agg, Object arg) {
this.agg = agg;
this.arg = arg;
}
@Override
public Object update(Object stored) {
if(stored==null) return arg;
else return agg.combine(stored, arg);
}
}