retry-kit

Coroutine-native retry with configurable backoff strategies for Kotlin.

Installation

Gradle (Kotlin DSL)

implementation("com.philiprehberger:retry-kit:0.1.5")

Maven

<dependency>
    <groupId>com.philiprehberger</groupId>
    <artifactId>retry-kit</artifactId>
    <version>0.1.5</version>
</dependency>

Usage

import com.philiprehberger.retrykit.*
import kotlin.time.Duration.Companion.milliseconds
import kotlin.time.Duration.Companion.seconds

// Simple retry with defaults (3 attempts, 100ms fixed backoff)
val result = retry {
    fetchFromApi()
}

// Retry with exponential backoff
val data = retry(
    maxAttempts = 5,
    backoff = BackoffStrategy.Exponential(100.milliseconds, max = 10.seconds),
) {
    httpClient.get("/data")
}

RetryPolicy DSL

val policy = retryPolicy {
    maxAttempts(5)
    exponentialBackoff(100.milliseconds, max = 10.seconds)
    jitter(0.1)
    retryOn<IOException>()
    onRetry { attempt, ex -> logger.warn("Attempt $attempt failed: $ex") }
}

val result = policy.execute {
    riskyOperation()
}

Backoff Strategies

// Fixed delay between retries
BackoffStrategy.Fixed(200.milliseconds)

// Exponential backoff (100ms, 200ms, 400ms, ...)
BackoffStrategy.Exponential(base = 100.milliseconds, max = 30.seconds)

// Exponential with jitter to avoid thundering herd
BackoffStrategy.ExponentialWithJitter(base = 100.milliseconds, max = 30.seconds, jitterFactor = 0.1)

API

Class / Function	Description
retry()	Suspend function that executes a block with retry logic
retryPolicy { }	DSL builder for creating reusable retry policies
RetryPolicy	Configurable retry policy with execute() method
BackoffStrategy.Fixed	Constant delay between retries
BackoffStrategy.Exponential	Exponentially increasing delay with a cap
BackoffStrategy.ExponentialWithJitter	Exponential backoff with random jitter

Development

./gradlew test       # Run tests
./gradlew check      # Run all checks
./gradlew build      # Build JAR

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License

MIT