Amsterdam

Amsterdam is a java library for throughput management.

It currently contains two key classes:

• TokenBucket: An implementation of the token bucket algorithm for defining throughput rates.
• RateLimiterFactory: This is a higher level service for decorating an object with a proxy which will limit the rate at which a method can be called.

Usage

Download the jar from ???.

Wrap an object in a proxy to limit the rate at which calls are made to its methods:

MyServiceInterface myService = new MyServiceImpl();
int bucketCapacity = 10;
FillRate bucketFillRate = FillRate.perSecond(10);
RateLimit rateLimit = new RateLimit(bucketCapacity, bucketFillRate);
MyServiceInterface rateLimitedService = new RateLimiterFactory().limitRate(myService, 
	methodMatching("rateLimitedMethodRegex.*"), TokenCostFunctions.fixedCost(1), rateLimit);
// ...
try {
	rateLimitedService.doSomething();
} catch (CapacityExceededException e) {
	// Maximim rate exceeded...
}

If the rate is exceeded a CapacityExceededException (a RuntimeException) is thrown.

To use the lower level Token Bucket directly:

TokenBuket tokenBucket = new TokenBucket(0, perMilli(1));
if (tokenBucket.getTokens(2)) {
  // Do something useful...
}

License

Amsterdam is released under the MIT license:

• http://www.opensource.org/licenses/MIT