storm-client/src/jvm/org/apache/storm/trident/state/CombinerValueUpdater.java

/**
 * 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 org.apache.storm.trident.state;

import org.apache.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);
        }
    }

    // helpful for debugging tests
    public Object getArg() {
        return arg;
    }

    public CombinerAggregator getAgg() {
        return agg;
    }
}