completable_futures_allOf_example.groovy

import groovy.transform.Canonical

import java.util.concurrent.CompletableFuture
import java.util.function.Function
import java.util.function.Supplier

final long serviceExecutionTime = 1000

def rand = new Random()
def initVal = rand.nextInt(100)

@Canonical
class RpcResult {
    Integer val
    Throwable error
}

//remote service call emulation
def rpcServiceSupplier = {Integer arg ->
    return {
        sleep(serviceExecutionTime)
        if (arg == 3) throw new IllegalArgumentException("Invalid arg=$arg")
        new RpcResult(val: arg * initVal)
    } as Supplier<RpcResult>
}


def args = 1..10 //some remote service call arguments


def futures = args
    .collect { rpcServiceSupplier(it) }
    .collect {
        CompletableFuture
            .supplyAsync(it)
            .exceptionally { err -> new RpcResult(error: err)}
    }

def result = CompletableFuture.allOf(futures as CompletableFuture[])
    .thenApply {
        futures.collect { it.join() }
    }


println result.join()