org.apache.zookeeper.server.util.RateLimiter Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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* See the License for the specific language governing permissions and
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*/
package org.apache.zookeeper.server.util;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.zookeeper.common.Time;
/**
* A class that provides simple interval-based rate limiting implementation.
*/
public class RateLimiter {
private final int rate;
private final long intervalInMs;
private long lastTimeReset;
private final AtomicInteger remained;
public RateLimiter(final int rate, final long interval, final TimeUnit unit) {
this.rate = rate;
this.intervalInMs = unit.toMillis(interval);
this.lastTimeReset = Time.currentElapsedTime();
this.remained = new AtomicInteger(rate);
}
public boolean allow() {
final long now = Time.currentElapsedTime();
// reset the rate if interval passed
if (now > lastTimeReset + intervalInMs) {
remained.set(rate);
lastTimeReset = now;
}
int value = remained.get();
boolean allowed = false;
// to handle race condition
while (!allowed && value > 0) {
allowed = remained.compareAndSet(value, value - 1);
value = remained.get();
}
return allowed;
}
}