Guava’s RateLimiter per minutes instead of seconds?

Question

I\'m trying to rate-limit the the number of accounts a user can create with my REST API.

I would have liked to use Guava\'s RateLimiter to only allow an IP

Answer 1

There's a class called SmoothRateLimiter.SmoothBursty inside Guava library that implements desired behavior but it has package local access, so we can't use it directly. There's also a Github issue to make access to that class public: https://github.com/google/guava/issues/1974

If you're not willing to wait until they release a new version of RateLimiter then you could use reflection to instantiate SmoothBursty rate limiter. Something like this should work:

Class sleepingStopwatchClass = Class.forName("com.google.common.util.concurrent.RateLimiter$SleepingStopwatch");
Method createStopwatchMethod = sleepingStopwatchClass.getDeclaredMethod("createFromSystemTimer");
createStopwatchMethod.setAccessible(true);
Object stopwatch = createStopwatchMethod.invoke(null);

Class burstyRateLimiterClass = Class.forName("com.google.common.util.concurrent.SmoothRateLimiter$SmoothBursty");
Constructor burstyRateLimiterConstructor = burstyRateLimiterClass.getDeclaredConstructors()[0];
burstyRateLimiterConstructor.setAccessible(true);

RateLimiter result = (RateLimiter) burstyRateLimiterConstructor.newInstance(stopwatch, maxBurstSeconds);
result.setRate(permitsPerSecond);
return result;

Yes, new version of Guava might brake your code but if you're willing to accept that risk this might be the way to go.