Fibers.java

package io.ryos.demos.fibers;

import static java.lang.System.out;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.SynchronousQueue;

public class FiberDemo {

  public static void main(String[] args) {
    // sync queue without any capacity.
    SynchronousQueue<Integer> syncQueue = new SynchronousQueue<>();

    // schedule a producer fiber to create numbers from 1 to n.
    Fiber.schedule(() -> {
      int counter = 0;
      while (true) {
        ++counter;
        var ct = Thread.currentThread();
        out.println(String.format("Putting the value: %d, Thread: %s", counter, ct.getName()));
        syncQueue.put(counter); // blocks
      }
    });

    out.println("Scheduled the producer fiber... - " + Thread.currentThread().getName());

    takeWhile(syncQueue, 5);

    out.println("Scheduled the consumer fiber... - " + Thread.currentThread().getName());
  }

  private static List<Integer> takeWhile(final SynchronousQueue<Integer> syncQueue, final int n) {

    // schedule another fiber, which consumes n integers.
    final Fiber<List<Integer>> fiber = Fiber.schedule(() -> {
      List<Integer> result = new ArrayList<>();
      for (var i = 0; i < n + 1; i++) {
        var take = syncQueue.take();  // blocks
        var ct = Thread.currentThread();
        out.println(String.format("Reading the value: %d, Thread: %s", take, ct.getName()));
        result.add(take);
      }
      return result;
    });

    return fiber.join();
  }
}