org.apache.rocketmq.shaded.io.opentelemetry.sdk.internal.RateLimiter Maven / Gradle / Ivy
/*
* Copyright The OpenTelemetry Authors
* SPDX-License-Identifier: Apache-2.0
*/
package org.apache.rocketmq.shaded.io.opentelemetry.sdk.internal;
import org.apache.rocketmq.shaded.io.opentelemetry.sdk.common.Clock;
import java.util.concurrent.atomic.AtomicLong;
/**
* This class was taken from Jaeger java client.
* https://github.com/jaegertracing/jaeger-client-java/blob/master/jaeger-core/src/main/java/io/jaegertracing/internal/samplers/RateLimitingSampler.java
*
* Variables have been renamed for clarity.
*
*
This class is internal and is hence not for public use. Its APIs are unstable and can change
* at any time.
*/
public class RateLimiter {
private final Clock clock;
private final double creditsPerNanosecond;
private final long maxBalance; // max balance in nano ticks
private final AtomicLong currentBalance; // last op nano time less remaining balance
/**
* Create a new RateLimiter with the provided parameters.
*
* @param creditsPerSecond How many credits to accrue per second.
* @param maxBalance The maximum balance that the limiter can hold, which corresponds to the rate
* that is being limited to.
* @param clock An implementation of the {@link Clock} interface.
*/
public RateLimiter(double creditsPerSecond, double maxBalance, Clock clock) {
this.clock = clock;
this.creditsPerNanosecond = creditsPerSecond / 1.0e9;
this.maxBalance = (long) (maxBalance / creditsPerNanosecond);
this.currentBalance = new AtomicLong(clock.nanoTime() - this.maxBalance);
}
/**
* Check to see if the provided cost can be spent within the current limits. Will deduct the cost
* from the current balance if it can be spent.
*/
public boolean trySpend(double itemCost) {
long cost = (long) (itemCost / creditsPerNanosecond);
long currentNanos;
long currentBalanceNanos;
long availableBalanceAfterWithdrawal;
do {
currentBalanceNanos = this.currentBalance.get();
currentNanos = clock.nanoTime();
long currentAvailableBalance = currentNanos - currentBalanceNanos;
if (currentAvailableBalance > maxBalance) {
currentAvailableBalance = maxBalance;
}
availableBalanceAfterWithdrawal = currentAvailableBalance - cost;
if (availableBalanceAfterWithdrawal < 0) {
return false;
}
} while (!this.currentBalance.compareAndSet(
currentBalanceNanos, currentNanos - availableBalanceAfterWithdrawal));
return true;
}
}