87 lines
2.1 KiB
Java
87 lines
2.1 KiB
Java
//: concurrency/ActiveObjectDemo.java
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// Can only pass constants, immutables, "disconnected
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// objects," or other active objects as arguments
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// to asynch methods.
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import java.util.concurrent.*;
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import java.util.*;
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import static net.mindview.util.Print.*;
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public class ActiveObjectDemo {
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private ExecutorService ex =
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Executors.newSingleThreadExecutor();
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private Random rand = new Random(47);
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// Insert a random delay to produce the effect
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// of a calculation time:
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private void pause(int factor) {
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try {
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TimeUnit.MILLISECONDS.sleep(
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100 + rand.nextInt(factor));
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} catch(InterruptedException e) {
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print("sleep() interrupted");
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}
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}
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public Future<Integer>
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calculateInt(final int x, final int y) {
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return ex.submit(() -> {
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print("starting " + x + " + " + y);
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pause(500);
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return x + y;
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});
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}
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public Future<Float>
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calculateFloat(final float x, final float y) {
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return ex.submit(() -> {
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print("starting " + x + " + " + y);
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pause(2000);
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return x + y;
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});
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}
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public void shutdown() { ex.shutdown(); }
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public static void main(String[] args) {
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ActiveObjectDemo d1 = new ActiveObjectDemo();
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// Prevents ConcurrentModificationException:
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List<Future<?>> results =
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new CopyOnWriteArrayList<>();
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for(float f = 0.0f; f < 1.0f; f += 0.2f)
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results.add(d1.calculateFloat(f, f));
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for(int i = 0; i < 5; i++)
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results.add(d1.calculateInt(i, i));
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print("All asynch calls made");
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while(results.size() > 0) {
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for(Future<?> f : results)
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if(f.isDone()) {
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try {
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print(f.get());
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} catch(InterruptedException |
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ExecutionException e) {
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throw new RuntimeException(e);
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}
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results.remove(f);
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}
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}
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d1.shutdown();
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}
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} /* Output: (85% Match)
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All asynch calls made
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starting 0.0 + 0.0
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starting 0.2 + 0.2
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0.0
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starting 0.4 + 0.4
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0.4
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starting 0.6 + 0.6
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0.8
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starting 0.8 + 0.8
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1.2
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starting 0 + 0
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1.6
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starting 1 + 1
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0
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starting 2 + 2
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2
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starting 3 + 3
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4
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starting 4 + 4
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6
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8
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*///:~
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