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This approach leverages JavaScript's built-in setTimeout and clearTimeout functions. We schedule a timeout to execute the function fn after t milliseconds, and we return a cancelFn that, when called, cancels this scheduled timeout.
In C, without a standard set of functions for asynchronous timeouts, it's less about algorithmic complexity and more about the overhead of managing threads, which varies based on the implementation details.
C does not have direct support for asynchronous delay management similar to setTimeout in JavaScript, particularly in standard libraries. Such functionality generally requires external libraries or platform-specific code for thread and timer management.
This alternative approach involves using Promises to manage asynchronous execution and potential cancelation. By wrapping the setTimeout within a Promise, we can have more control over its execution and cancelation by managing the Promise lifecycle.
Time Complexity and space complexity would depend on the specific threading mechanism and the use of synchronization primitives.
1import java.util.concurrent.CompletableFuture;
2import java.util.concurrent.TimeUnit;
3
4public class PromiseTimeout {
5 public static CompletableFuture<Void> cancellable(Runnable fn, int t) {
6 CompletableFuture<Void> promise = new CompletableFuture<>();
7
8 ScheduledExecutorService scheduledExecutor = Executors.newScheduledThreadPool(1);
9
10 scheduledExecutor.schedule(() -> {
11 if (!promise.isDone()) {
12 fn.run();
13 promise.complete(null);
14 }
15 }, t, TimeUnit.MILLISECONDS);
16
17 return promise; // Caller should complete this promise to cancel
18 }
19
20 public static void main(String[] args) throws Exception {
21 Runnable fn = () -> System.out.println(10);
22 CompletableFuture<Void> future = cancellable(fn, 500);
23
24 // Simulate cancel call after 200 ms
25 Thread.sleep(200);
26 future.complete(null); // Cancels the execution of fn if not already done
27 }
28}Using Java's CompletableFuture alongside a scheduled executor service allows defining timeout behavior with a Promise-like setup. Cancellations are achieved by completing the future manually before execution.