cancelling CompletableFuture

cancel_CompletableFuture.groovy

import java.util.concurrent.FutureTask
import java.util.concurrent.CompletableFuture
import java.util.concurrent.Callable
import java.util.concurrent.CancellationException

// 指定時間寝て、夢見SCOREを返す
int dream(int millis) {
    try {
        println "$millis ms 寝る..."
        Thread.sleep(millis)
        println "よく寝た～"
        def c = 5;
        def b = (0..<c).collect { Math.random() }.sum() / (double)c
        return 100 * (1 - Math.pow(1.7, -b * millis / 1000.0))
    }
    catch(InterruptedException e) {
        println "途中で起こされた!!"
        return Integer.MIN_VALUE
    }
}

def a () {
    def future = CompletableFuture.supplyAsync { dream(3000) }.thenAccept { println "Yumemi score: $it" }
    return future
}
def b() {
    def task = new FutureTask({ dream(3000) } as Callable)
    def future = CompletableFuture.supplyAsync { task.run(); task.get() }.thenAccept { println "Yumemi score: $it" }
    future.exceptionally { e -> if (e instanceof CancellationException) task.cancel(true) }
    return future
}
println "- a ----------------"
a().get()
println "- b ----------------"
b().get()
println "- cancel a ---------"
a().cancel(true); sleep(3500);
println "- cancel b ---------"
b().cancel(true); sleep(3500);

output_example.txt

- a ----------------
3000 ms 寝る...
よく寝た～
Yumemi score: 48
- b ----------------
3000 ms 寝る...
よく寝た～
Yumemi score: 60
- cancel a ---------
3000 ms 寝る...
よく寝た～
- cancel b ---------
3000 ms 寝る...
途中で起こされた!!