java non blocking notifier
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;
public class GetTaskNotificationWithoutBlocking {
public static void main(String... argv) throws Exception {
ExampleService svc = new ExampleService();
GetTaskNotificationWithoutBlocking listener = new GetTaskNotificationWithoutBlocking();
CompletableFuture<String> f = CompletableFuture.supplyAsync(svc::work);
f.thenAccept(listener::notify);
System.out.println("Exiting main()");
}
void notify(String msg) {
System.out.println("Received message: " + msg);
}
}
class ExampleService {
String work() {
sleep(7000, TimeUnit.MILLISECONDS); /* Pretend to be busy... */
char[] str = new char[5];
ThreadLocalRandom current = ThreadLocalRandom.current();
for (int idx = 0; idx < str.length; ++idx)
str[idx] = (char) ('A' + current.nextInt(26));
String msg = new String(str);
System.out.println("Generated message: " + msg);
return msg;
}
public static void sleep(long average, TimeUnit unit) {
String name = Thread.currentThread().getName();
long timeout = Math.min(exponential(average), Math.multiplyExact(10, average));
System.out.printf("%s sleeping %d %s...%n", name, timeout, unit);
try {
unit.sleep(timeout);
System.out.println(name + " awoke.");
} catch (InterruptedException abort) {
Thread.currentThread().interrupt();
System.out.println(name + " interrupted.");
}
}
public static long exponential(long avg) {
return (long) (avg * -Math.log(1 - ThreadLocalRandom.current().nextDouble()));
}
}