令牌桶Java实现

package com.sohu.sns.data.recommend.server.utils.tokenBucket; import static java.util.concurrent.TimeUnit.MICROSECONDS; import static java.util.concurrent.TimeUnit.NANOSECONDS; /** * */ public abstract class RateLimiter { protected double maxTokens; protected double availableTokens; protected long startNanos; protected long nextGenTokenMicros; protected double stableIntervalTokenMicros; protected final Object mutex = new Object(); public void setRate(double tokenPerSecond){ if (tokenPerSecond < 0 ){ throw new IllegalArgumentException("tokenPerSecond must be positive."); } synchronized (mutex){ doSetRate(tokenPerSecond); } } protected abstract void doSetRate(double tokenPerSecond); public abstract void syncAvailableToken(long nowMicros); public abstract double getToken(double requiredToken); public long duration(){ return MICROSECONDS.convert(System.nanoTime() - startNanos,NANOSECONDS); } public static Builder builder(){ return new Builder(); } public static class Builder<T extends RateLimiter> { private double tokenPerSecond; private RateLimiterType type; public Builder withType(RateLimiterType type){ this.type = type; return this; } public Builder withTokenPerSecond(double tokenPerSecond){ this.tokenPerSecond = tokenPerSecond; return this; } public T build(){ switch (type){ case TB: return (T)buildSmoothTokenBucketLimiter(); case LB: return null; case FFTB: return (T)buildFailFastTokenBucketLimiter(); default: return (T)buildSmoothTokenBucketLimiter(); } } private SmoothTokenBucketLimiter buildSmoothTokenBucketLimiter(){ SmoothTokenBucketLimiter limiter = new SmoothTokenBucketLimiter(); limiter.startNanos = System.nanoTime(); limiter.setRate(tokenPerSecond); return limiter; } private FailFastTokenBucketLimiter buildFailFastTokenBucketLimiter(){ FailFastTokenBucketLimiter limiter = new FailFastTokenBucketLimiter(); limiter.startNanos = System.nanoTime(); limiter.setRate(tokenPerSecond); return limiter; } } public static enum RateLimiterType { /** * token bucket */ TB, /** * leaky bucket */ LB, /** * 没有可用token 抛出异常的token bucket */ FFTB; } }