Coroutines Example

main.kt

import kotlinx.coroutines.*
import kotlinx.coroutines.experimental.*
import kotlin.system.measureTimeMillis

fun main() {
    println("start")
    println(bunchOfRequests().toString())
    println("stop")
}

fun bunchOfRequests(): Map<String, Long> {
    val map = emptyMap<String, Long>().toMutableMap()
    runBlocking {
        val list: List<Deferred<Map<String, Long>>> = listOf(
            async { aRequest(5000) },
            async { aRequest(7000) },
            async { aRequest(2000) }
        )
        list.forEach {
            it.await().entries.forEach {entry ->
                map[entry.key] = entry.value
            }
        }
    }
    return map
}

suspend fun aRequest(n: Long): Map<String, Long> {
    delay(n)
    println(n.toString())
    return hashMapOf(n.toString() to n)
}