How to Use Resilience4j for Ratelimiters

1. What is Rate Limiting?

Rate limiting, or limiting the frequency of requests, is a crucial technique in software development, particularly for creating scalable and robust applications. One tool that provides solutions for rate limiting is the Resilience4j library for Java. In this article, we'll explore how Resilience4j supports rate limiting and how it can be used to enhance the resilience of applications.

2. What is Resilience4j?

Resilience4j is a lightweight library for building fault-tolerant Java applications. It offers several modules for addressing various tasks related to system resilience, such as Circuit Breaker, RateLimiter, Retry, Bulkhead, and TimeLimiter.

These modules help control and manage the behavior of your applications when interacting with external systems or handling internal operations.

3. RateLimiting in Resilience4j

Ratelimiting is a process that limits the number of requests sent to a particular service or resource over a specific period. This helps prevent service overload and ensures a more even distribution of load.

In Resilience4j, the RateLimiter module allows configuring the number of permitted requests within a certain time interval. This can be useful, for example, when interacting with external APIs that have request frequency limitations.

4. Usage Example

// Creating a RateLimiter instance
RateLimiter rateLimiter = RateLimiter.of("serviceName", RateLimiterConfig.custom()
    .limitRefreshPeriod(Duration.ofSeconds(1))
    .limitForPeriod(10)
    .timeoutDuration(Duration.ofSeconds(1))
    .build());

// Using RateLimiter with a functional interface
Supplier<String> restrictedSupplier = RateLimiter.decorateSupplier(rateLimiter, () -> {
    // request logic
    return "response";
});

// Executing with limitation
try {
    String response = restrictedSupplier.get();
    // response handling
} catch (RequestNotPermitted exception) {
    // exception handling
}

5. Conclusion