Example1.kt

// https://akarnokd.blogspot.ru/2017/09/rxjava-vs-kotlin-coroutines-quick-look.html
// Refactoring
import kotlinx.coroutines.experimental.*

suspend fun f1(i: Int): Int {
    Thread.sleep(if (i != 2) 2000L else 200L)
    return 1
}

suspend fun f2(i: Int): Int {
    Thread.sleep(if (i != 2) 2000L else 200L)
    return 2
}

inline fun <T> retry(n: Int, block: (Int) -> T): T {
    var ex: TimeoutException? = null
    repeat(n) { i ->
        try { return block(i) }
        catch (e: TimeoutException) {
            println("Failed with $e")
            ex = e
        }
    }
    throw ex!! /* rethrow last failure */
}

suspend fun coroutineWay() {
    val t0 = System.currentTimeMillis()
    retry<Unit>(3) { i ->
        withTimeout(500) {
            println("Attempt ${i + 1} at T=${System.currentTimeMillis() - t0}")
            val v1 = async(CommonPool) { f1(i) }
            val v2 = async(CommonPool) { f2(i) }
            val r1 = v1.await()
            val r2 = v2.await()
            println(r1 + r2)
            println("End at T=${System.currentTimeMillis() - t0}")
        }
    }
}

fun main(args: Array<String>) = runBlocking {
    coroutineWay()