storm-client/src/jvm/org/apache/storm/trident/windowing/InMemoryWindowsStoreFactory.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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.windowing;

import java.util.List;
import java.util.Map;
import org.apache.storm.trident.operation.TridentCollector;

/**
 * InMemoryWindowsStoreFactory contains a single instance of {@link InMemoryWindowsStore} which will be used for storing tuples and triggers
 * of the window. The same InMemoryWindowsStoreFactory instance is passed to {@link WindowsStateUpdater}, which removes successfully emitted
 * triggers from the same {@code inMemoryWindowsStore} instance in {@link WindowsStateUpdater#updateState(WindowsState, List,
 * TridentCollector)}.
 */
public class InMemoryWindowsStoreFactory implements WindowsStoreFactory {

    private InMemoryWindowsStore inMemoryWindowsStore;

    @Override
    public WindowsStore create(Map<String, Object> topoConf) {
        if (inMemoryWindowsStore == null) {
            inMemoryWindowsStore = new InMemoryWindowsStore();
        }
        return inMemoryWindowsStore;
    }
}