Rate Limiting Pattern #2973

[skamble2]

Pull Request Template

What does this PR do?

This PR implements the Rate Limiting Design Pattern in Java using three different strategies:

• Token Bucket
• Fixed Window
• Adaptive Rate Limiter

It simulates concurrent client requests to multiple services (S3, DynamoDB, Lambda) and applies appropriate rate-limiting logic to manage request throughput, prevent system overload, and simulate elastic behavior under pressure.

[github-actions]

PR Summary

This PR implements the Rate Limiting Design Pattern in Java using three different strategies: Token Bucket, Fixed Window, and Adaptive Rate Limiter. It simulates concurrent client requests to multiple services (S3, DynamoDB, Lambda) and applies appropriate rate-limiting logic to manage request throughput, prevent system overload, and simulate elastic behavior under pressure. The implementation includes comprehensive unit tests and diagrams.

Changes

File	Summary
pom.xml	The rate-limiting-pattern module was added to the project's modules.
rate-limiting-pattern/README.md	A comprehensive README file was added, explaining the rate limiting pattern, its implementation, and including diagrams for each strategy.
rate-limiting-pattern/etc/AdaptiveRateLimiter.png	New file.
rate-limiting-pattern/etc/FixedWindowRateLimiter.png	New file.
rate-limiting-pattern/etc/TokenBucketRateLimiter.png	New file.
rate-limiting-pattern/etc/UMLClassDiagram.png	New file.
rate-limiting-pattern/pom.xml	A pom.xml file was added for the rate-limiting-pattern module, defining dependencies and build configurations.
rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/AdaptiveRateLimiter.java	This class implements an adaptive rate limiter that adjusts the rate based on system health, reducing the rate when throttling occurs and recovering periodically.
rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/App.java	This class simulates concurrent client requests to multiple services and applies rate limiting logic using the implemented strategies. It also prints statistics about the requests.
rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/FindCustomerRequest.java	This class represents a rate-limited customer lookup operation, wrapping the rate limiting logic and simulating a business request.
rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/FixedWindowRateLimiter.java	This class implements a fixed window rate limiter that allows up to a certain number of requests within a fixed time window.
rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/RateLimitException.java	New file.
rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/RateLimitOperation.java	New file.
rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/RateLimiter.java	New file.
rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/ServiceUnavailableException.java	New file.
rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/ThrottlingException.java	New file.
rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/TokenBucketRateLimiter.java	This class implements a token bucket rate limiter that allows requests to proceed as long as there are tokens available in the bucket.
rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/AdaptiveRateLimiterTest.java	Unit tests for the AdaptiveRateLimiter class, including tests for limit decrease on throttling and gradual increase when healthy.
rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/AppTest.java	Unit tests for the App class, covering various scenarios including successful requests, throttling, and service unavailability.
rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/AppTestUtils.java	New file.
rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/ConcurrencyTests.java	Concurrency tests for the rate limiters, ensuring they handle concurrent requests correctly and that the adaptive limiter adjusts under load.
rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/ExceptionTests.java	Unit tests for custom exceptions, verifying that they contain the expected information.
rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FindCustomerRequestTest.java	Unit tests for the FindCustomerRequest class, covering scenarios under and exceeding rate limits.
rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FixedWindowRateLimiterTest.java	Unit tests for the FixedWindowRateLimiter class, including tests for counter reset after the window and limit enforcement.
rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/RateLimitOperationTest.java	New file.
rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/RateLimiterTest.java	New file.
rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/TokenBucketRateLimiterTest.java	Unit tests for the TokenBucketRateLimiter class, including tests for burst requests, token refill, and handling multiple services.

---

autogenerated by presubmit.ai

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (3)

• 331beb9: Updated README.md. All test case passed. Updated with Google Java Guidelines
• ed01b7b: Added Class Diagram and Flow Diagrams for Adaptive, Fixed Window and Token Bucket Rate Limiter
• dd0fc2b: need to fix one test case shouldGraduallyIncreaseLimitWhenHealthy failing for AdaptiveRateLimiter.java

Files Processed (25)

• pom.xml (2 hunks)
• rate-limiting-pattern/README.md (1 hunk)
• rate-limiting-pattern/etc/AdaptiveRateLimiter.png (0 hunks)
• rate-limiting-pattern/etc/FixedWindowRateLimiter.png (0 hunks)
• rate-limiting-pattern/etc/TokenBucketRateLimiter.png (0 hunks)
• rate-limiting-pattern/etc/UMLClassDiagram.png (0 hunks)
• rate-limiting-pattern/pom.xml (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/AdaptiveRateLimiter.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/App.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/FindCustomerRequest.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/FixedWindowRateLimiter.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/RateLimitException.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/RateLimitOperation.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/RateLimiter.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/ServiceUnavailableException.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/ThrottlingException.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/TokenBucketRateLimiter.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/AdaptiveRateLimiterTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/ConcurrencyTests.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/ExceptionTests.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FindCustomerRequestTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FixedWindowRateLimiterTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/RateLimitOperationTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/RateLimiterTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/TokenBucketRateLimiterTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 1f3ad40: Updated parent pom Rate Limiting pattern #2973

Files Processed (24)

• rate-limiting-pattern/README.md (1 hunk)
• rate-limiting-pattern/etc/AdaptiveRateLimiter.png (0 hunks)
• rate-limiting-pattern/etc/FixedWindowRateLimiter.png (0 hunks)
• rate-limiting-pattern/etc/TokenBucketRateLimiter.png (0 hunks)
• rate-limiting-pattern/etc/UMLClassDiagram.png (0 hunks)
• rate-limiting-pattern/pom.xml (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/AdaptiveRateLimiter.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/App.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/FindCustomerRequest.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/FixedWindowRateLimiter.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/RateLimitException.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/RateLimitOperation.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/RateLimiter.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/ServiceUnavailableException.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/ThrottlingException.java (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/TokenBucketRateLimiter.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/AdaptiveRateLimiterTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/ConcurrencyTests.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/ExceptionTests.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FindCustomerRequestTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FixedWindowRateLimiterTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/RateLimitOperationTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/RateLimiterTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/TokenBucketRateLimiterTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 3526c05: Updated parent pom Rate Limiting pattern #2973

Files Processed (1)

• pom.xml (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 26cb1b2: fixed shouldResetCounterAfterWindow() test Rate Limiting pattern #2973

Files Processed (1)

• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FixedWindowRateLimiterTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (1)

• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FixedWindowRateLimiterTest.java [24-28]

  enhancement: "Improve test timing reliability."

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 8afefee: formatting fixed Rate Limiting pattern #2973

Files Processed (1)

• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FixedWindowRateLimiterTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (1)

• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FixedWindowRateLimiterTest.java [26-29]

  enhancement: "Improve window reset check in shouldResetCounterAfterWindow test."

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (6)

• 54d7396: added test coverage for app.java and fixed random to be thread safe Rate Limiting pattern #2973
• 4e886f8: added test coverage for app.java and fixed random to be thread safe Rate Limiting pattern #2973
• 0889442: added test coverage for app.java and fixed random to be thread safe Rate Limiting pattern #2973
• 5120195: added test coverage for app.java and fixed random to be thread safe Rate Limiting pattern #2973
• 3a9de27: added test coverage for app.java and fixed random to be thread safe Rate Limiting pattern #2973
• fe253e4: added test coverage for app.java and fixed random to be thread safe Rate Limiting pattern #2973

Files Processed (5)

• rate-limiting-pattern/pom.xml (1 hunk)
• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/App.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/AppTest.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/AppTestUtils.java (1 hunk)
• rate-limiting-pattern/src/test/java/com/iluwatar/rate/limiting/pattern/FindCustomerRequestTest.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• b6002a5: added test coverage for app.java and fixed random to be thread safe Rate Limiting pattern #2973

Files Processed (1)

• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/App.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• dfe6753: fixed random to be thread safe Rate Limiting pattern #2973

Files Processed (1)

• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/App.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[github-actions]

✅ LGTM!

Review Summary

Commits Considered (1)

• 28e8b4a: fixed random to be thread safe Rate Limiting pattern #2973

Files Processed (1)

• rate-limiting-pattern/src/main/java/com/iluwatar/rate/limiting/pattern/App.java (1 hunk)

Actionable Comments (0)

Skipped Comments (0)

[sonarqubecloud]

Quality Gate passed

Issues
13 New issues
0 Accepted issues

Measures
0 Security Hotspots
91.9% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud