Control Flow

uni provides utilities for handling failures gracefully and managing resources properly.

Overview

Component	Description
Retry	Automatic retry with backoff strategies
Circuit Breaker	Prevent cascade failures
Rate Limiter	Throttle operation throughput (JVM)
Cache	TTL and LRU caching
Resource	Safe resource acquisition and release
Background Task	Cancellable, progress-pollable background worker

Quick Example

import wvlet.uni.control.{Retry, CircuitBreaker, Resource}

// Retry a flaky operation
val result = Retry.withBackoff(maxRetry = 3).run {
  callExternalService()
}

// Protect with circuit breaker
val breaker = CircuitBreaker(maxFailures = 5)
val protected = breaker.protect {
  riskyOperation()
}

// Safe resource handling
Resource.withResource(openConnection()) { conn =>
  useConnection(conn)
} // Automatically closed

When to Use

Retry

• Network calls that may fail transiently
• Database operations during high load
• API calls with rate limiting

Circuit Breaker

• External service dependencies
• Preventing cascade failures
• Graceful degradation

Caching

• Expensive computations
• Frequently accessed data
• Rate-limited API responses

Resource Management

• File handles
• Database connections
• Network sockets

Package

import wvlet.uni.control.*