retry4k

Retry4k is resilience and fault tolerance library written in kotlin.

Usage

//retry maximum of 3 times if nullpointer exception occurred
 RetryOptions.Builder<String>().maxAttempt(3).retryOnException(NullPointerException::class.java).build()

//retry maximum of 3 times if action returns returns result with string retryme and wait for 1000ms before every retry

 val retryOnResult: (String) -> Boolean = {result -> result == "retryme"}

 RetryOptions.Builder<String>().maxAttempt(3).retryOnResult(retryOnResult).waitDuration(1000).build()

//Don't retry if the exception thrown by action is IllegalArgumentException. 

 val retryOnResult: (String) -> Boolean = {result -> result == "retryme"}

 RetryOptions.Builder<String>().waitDuration(1000).maxAttempt(5).retryOnException(NullPointerException::class.java).retryOnResult(retryOnResult).ignoreOnException(IllegalArgumentException::class.java).build()

//Do some action before every retry attempt and after completion of either successfull or failure execution of action. 

 val beforeRetry:(Throwable?, String?, Int) -> Unit = { throwable,result, cuurentAttempt -> println("attempting for $cuurentAttempt time)}
 
 val onCompleted:(Throwable?, String?, Int) -> Unit = { throwable,result, cuurentAttempt -> println("completed after $cuurentAttempt times)}
 
  val retryStrategy = RetryOptions.Builder<String>().maxAttempt(5).retryOnException(NullPointerException::class.java)
                 .doOnBeforeRetry(beforeRetry).doOnCompleted(onCompleted).build()

Execution

    val retryOption = RetryOptions.Builder<String>().maxAttempt(3).retryOnException(NullPointerException::class.java).build()
    val retryExecutor = RetryExecutor(retryOption)
    retryExecutor.execute { business logic }

TODO:

• allow option to define custom wait strategy
• implement multiple backOff strategy (exponential, Jitter etc)
• publish as maven artifact
• pluggable metric publisher (dropwizard, micrometer)
• DSL based retryOptions