storm-client/src/jvm/org/apache/storm/streams/processors/StateQueryProcessor.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.streams.processors;

import org.apache.storm.state.KeyValueState;
import org.apache.storm.streams.Pair;
import org.apache.storm.streams.StreamState;

public class StateQueryProcessor<K, V> extends BaseProcessor<K> implements StatefulProcessor<K, V> {
    private final StreamState<K, V> streamState;
    private KeyValueState<K, V> keyValueState;

    public StateQueryProcessor(StreamState<K, V> streamState) {
        this.streamState = streamState;
    }

    @Override
    public void initState(KeyValueState<K, V> keyValueState) {
        this.keyValueState = keyValueState;
    }

    public StreamState<K, V> getStreamState() {
        return streamState;
    }

    @Override
    protected void execute(K key) {
        V value = keyValueState.get(key);
        if (value != null) {
            context.forward(Pair.of(key, value));
        }
    }
}