It’s been a while since I’ve been working on this project. It is a rate limiter based on the atomic rate limiter from Resilience4j. The key difference is that the atomic rate limiter gets the permissions assigned per cycle while the refill-rate-limiter will split the permissions in a cycle and gradually refill them. In an essence it simulates a token bucket algorithm however it uses the atomic rate limiter internals

Using it is very simple.
Import it using maven.

	<dependencies>
        ...
		<dependency>
			<groupId>io.github.gkatzioura</groupId>
			<artifactId>refill-rate-limiter</artifactId>
			<version>1.0</version>
		</dependency>
		<dependency>
			<groupId>io.github.resilience4j</groupId>
			<artifactId>resilience4j-ratelimiter</artifactId>
			<version>1.7.1</version>
		</dependency>
        ...
	</dependencies>

And use it in your code base.

...
        RefillRateLimiterConfig refillRateLimiterConfig = new RefillRateLimiterConfig.Builder()
                .limitRefreshPeriod(Duration.of(2, ChronoUnit.SECONDS))
                .limitForPeriod(1)
                .permitCapacity(1)
                .build();

        refillRateLimiter = new RefillRateLimiter("default", refillRateLimiterConfig, io.vavr.collection.HashMap.empty());
...

        boolean allowed = refillRateLimiter.acquirePermission(1);

Just like Resilience4j it also has Apache Licence V2.
It spawned from an pr on the Resilience4j, since the merge time took longer I made it available as a standalone implementation. It would not hurt if you thumps up on pr so it ends up to the place it belongs 😉

A description of the algorithm can be found on GitHub. Benchmarks and integrations will follow.