storm-client/src/jvm/org/apache/storm/utils/WindowedTimeThrottler.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.utils;

public class WindowedTimeThrottler {
    long windowMillis;
    int maxAmt;
    long windowStartTime;
    int windowEvents = 0;

    public WindowedTimeThrottler(Number windowMillis, Number maxAmt) {
        this.windowMillis = windowMillis.longValue();
        this.maxAmt = maxAmt.intValue();
        windowStartTime = System.currentTimeMillis();
    }

    public boolean isThrottled() {
        resetIfNecessary();
        return windowEvents >= maxAmt;
    }

    //returns void if the event should continue, false if the event should not be done
    public void markEvent() {
        resetIfNecessary();
        windowEvents++;

    }

    private void resetIfNecessary() {
        long now = System.currentTimeMillis();
        if (now - windowStartTime > windowMillis) {
            windowStartTime = now;
            windowEvents = 0;
        }
    }
}