gregopet / kotlin-ratpack-coroutines

Coroutine support for Ratpack apps written in Kotlin

Coroutines for Kotlin Ratpack apps

This project contains a minimal implementation of coroutines for Ratpack apps written in Kotlin.

Basics

Ratpack apps operate on two types of threads:

• a compute thread handles the request in general by computing values and rendering them back to the client

• a blocking thread is used for any work that must wait on a slow resource (e.g. a database or a REST request)

It is imperative to use the correct thread type for a certain type of work to achieve peak performance. Ratpack gives developers the tools to achieve this using its own version of promises but this can lead to the so-called callback hell.

Kotlin’s coroutines are an even nicer way of combating callback hell (one of the main motivations for coroutines, in fact) so this is an attempt to combine Ratpack’s promises with Kotlin’s coroutines.

Installation

Currently the easiest way to 'install' this library is to simply copy the coroutines.kt file into your project. You will need to add kotlinx-coroutines-core and of course Ratpack - see the build.gradle.kts for the exact includes.

If this library proves useful, grows more complex and/or more people are interested I might publish it somewhere for easier inclusion in projects.

Usage

// Computation blocks
fun hello(ctx: Context) = ctx.async {
	val name = await { Database.fetchName() }
	ctx.response.send("Hello, $name!")
}

// Resolve a Ratpack promise
fun echo(ctx: Context) = ctx.async {
	val body = ctx.request.body.await()
	ctx.response.send(body)
}

Warning

This library was not extensively tested in production yet so use it at your own risk.

Contributions are welcome!