storm-client/src/jvm/org/apache/storm/trident/windowing/strategy/TumblingCountWindowStrategy.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.strategy;

import org.apache.storm.trident.windowing.config.WindowConfig;
import org.apache.storm.windowing.CountEvictionPolicy;
import org.apache.storm.windowing.CountTriggerPolicy;
import org.apache.storm.windowing.EvictionPolicy;
import org.apache.storm.windowing.TriggerHandler;
import org.apache.storm.windowing.TriggerPolicy;

/**
 * This class represents tumbling window strategy based on the window count from the given {@code slidingCountWindow} configuration. In this
 * strategy , window and sliding lengths are equal.
 */
public final class TumblingCountWindowStrategy<T> extends BaseWindowStrategy<T> {

    public TumblingCountWindowStrategy(WindowConfig tumblingCountWindow) {
        super(tumblingCountWindow);
    }

    /**
     * Returns a {@code TriggerPolicy} which triggers for every count of given sliding window.
     */
    @Override
    public TriggerPolicy<T, ?> getTriggerPolicy(TriggerHandler triggerHandler, EvictionPolicy<T, ?> evictionPolicy) {
        return new CountTriggerPolicy<>(windowConfig.getSlidingLength(), triggerHandler, evictionPolicy);
    }

    /**
     * Returns an {@code EvictionPolicy} instance which evicts elements after a count of given window length.
     */
    @Override
    public EvictionPolicy<T, ?> getEvictionPolicy() {
        return new CountEvictionPolicy<>(windowConfig.getWindowLength());
    }
}