Coroutine-Call.kt

suspend fun coroutine() =
    coroutineScope {
        // concurrent call action 1 and 2, cost 200ms
        val delay100res = async(Dispatchers.IO) { getAwaitResponse(100) }
        val delay200res = async(Dispatchers.IO) { getAwaitResponse(200) }

        // blocking call, need return value from action 1 and 2, cost 300ms
        val period1 = delay100res.await()["totalTimeMillis"]!! + delay200res.await()["totalTimeMillis"]!!
        val delay300res = async(Dispatchers.IO) { getAwaitResponse(period1) }

        // concurrent call action 4 and 5, cost 500ms
        val period2 = delay300res.await()["totalTimeMillis"]!!
        val delay400res = async(Dispatchers.IO) { getAwaitResponse(period2 + 100) }
        val delay500res = async(Dispatchers.IO) { getAwaitResponse(period2 + 200) }

        mapOf(
            "delay100res" to delay100res.await()["totalTimeMillis"]!!,
            "delay200res" to delay200res.await()["totalTimeMillis"]!!,
            "delay300res" to delay300res.await()["totalTimeMillis"]!!,
            "delay400res" to delay400res.await()["totalTimeMillis"]!!,
            "delay500res" to delay500res.await()["totalTimeMillis"]!!
        )
    }

private suspend fun getAwaitResponse(ms: Long) = webClient.get()
    .uri("http://$domain:8888/delay/ms/$ms")
    .retrieve()
    .awaitBody<Map<String, Long>>()