Ktor REST response and async code execution - kotlin-coroutines

Question

Problem:
I would like to unblock my KTOR response from portions of the code that take longer and can be executed in async manner after the fact.
The core business logic for REST response should not wait for the async tasks such as sending email, kafka event etc..
What I have tried:
I get the desired results with this code example. I can see that the rest response is returned immediately and does not wait on the delayed tasks (email and Kafka message).
I am unclear at this point if I need to keep these lines inside the runBlocking code
val patient = PatientService.addPatient()
//Return REST response
call.respond(patient)
Question
If I keep it out of the runblocking code, the entire rest response is blocked until the email and kafka event code is complete.
Is this the right approach to offload certain delayed code execution
logic from the main REST API response in KTOR?
fun Route.patientRoute(){
route("/patient") {
post (""){
runBlocking {
val patient = PatientService.addPatient() //..Business logic to add a new patient
launch { //unblock the REST response from certain async. tasks
sendKafkaEvent()
sendEmail()
}
call.respond(patient) //Return REST response
}
}
}
}
suspend fun sendEmail() {
delay(5000L) //Mock some delay in the operation
}
suspend fun sendKafkaMessage() {
delay(5000L) //Mock some delay in the operation
}

Answer 1

I would firstly run asynchronous tasks and then call to PatientService.addPatient() to pass its returned value for call.respond.
Additionally, you can specify a different dispatcher for your tasks.
post("") {
launch(Dispatchers.IO) {
sendEmail()
}
launch(Dispatchers.IO) {
sendKafkaEvent()
}
call.respond(PatientService.addPatient())
}