BAEL-679. Java 9 Reactive Streams. Second draft.
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shankarps
parent
a055ab5f81
commit
6def745640
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package com.baeldung.java9.reactive;
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import java.util.ArrayList;
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import java.util.concurrent.Flow.Subscriber;
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import java.util.concurrent.Flow.Subscription;
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public class BaeldungBatchSubscriberImpl<T> implements Subscriber<String> {
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private Subscription subscription;
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private boolean completed = false;
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private int counter;
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private ArrayList<String> buffer;
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public static final int BUFFER_SIZE = 5;
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public BaeldungBatchSubscriberImpl() {
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buffer = new ArrayList<String>();
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}
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public boolean isCompleted() {
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return completed;
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}
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public void setCompleted(boolean completed) {
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this.completed = completed;
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}
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public int getCounter() {
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return counter;
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}
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public void setCounter(int counter) {
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this.counter = counter;
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}
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@Override
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public void onSubscribe(Subscription subscription) {
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this.subscription = subscription;
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subscription.request(BUFFER_SIZE);
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}
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@Override
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public void onNext(String item) {
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buffer.add(item);
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// if buffer is full, process the items.
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if (buffer.size() >= BUFFER_SIZE) {
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processBuffer();
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subscription.request(BUFFER_SIZE);
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} else if(buffer.size() == 0) {
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// If buffer empty, request more items.
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subscription.request(BUFFER_SIZE);
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}
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}
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private void processBuffer() {
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if (buffer.isEmpty())
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return;
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// Process all items in the buffer. Here, we just print it and sleep for 1 second.
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System.out.print("Processed items: ");
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buffer.stream()
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.forEach(item -> {
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System.out.print(" " + item);
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});
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System.out.println();
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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counter = counter + buffer.size();
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buffer.clear();
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}
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@Override
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public void onError(Throwable t) {
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t.printStackTrace();
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}
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@Override
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public void onComplete() {
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completed = true;
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// process any remaining items in buffer before
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processBuffer();
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subscription.cancel();
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}
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}
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package com.baeldung.java9.reactive;
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import java.util.concurrent.Flow.Subscriber;
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import java.util.concurrent.Flow.Subscription;
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public class BaeldungSubscriberImpl<T> implements Subscriber<String> {
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private Subscription subscription;
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private boolean completed = false;
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private int counter;
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public boolean isCompleted() {
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return completed;
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}
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public void setCompleted(boolean completed) {
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this.completed = completed;
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}
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public int getCounter() {
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return counter;
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}
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public void setCounter(int counter) {
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this.counter = counter;
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}
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@Override
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public void onSubscribe(Subscription subscription) {
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this.subscription = subscription;
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subscription.request(1);
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}
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@Override
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public void onNext(String item) {
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try {
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Thread.sleep(1000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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counter++;
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System.out.println("Processed item : " + item);
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subscription.request(1);
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}
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@Override
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public void onError(Throwable t) {
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t.printStackTrace();
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}
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@Override
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public void onComplete() {
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completed = true;
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subscription.cancel();
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}
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}
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package com.baeldung.java9.reactive;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertTrue;
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import java.util.concurrent.ForkJoinPool;
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import java.util.concurrent.SubmissionPublisher;
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import java.util.concurrent.TimeUnit;
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import java.util.stream.IntStream;
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import org.junit.Before;
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import org.junit.Rule;
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import org.junit.Test;
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import org.junit.rules.Stopwatch;
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public class BaeldungBatchSubscriberImplTest {
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private static final int ITEM_SIZE = 10;
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private SubmissionPublisher<String> publisher;
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private BaeldungBatchSubscriberImpl<String> subscriber;
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@Before
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public void initialize() {
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this.publisher = new SubmissionPublisher<String>(ForkJoinPool.commonPool(), 6);
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this.subscriber = new BaeldungBatchSubscriberImpl<String>();
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publisher.subscribe(subscriber);
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}
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@Rule
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public Stopwatch stopwatch = new Stopwatch() {
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};
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@Test
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public void testReactiveStreamCount() {
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IntStream.range(0, ITEM_SIZE)
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.forEach(item -> publisher.submit(item + ""));
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publisher.close();
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do {
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// wait for subscribers to complete all processing.
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try {
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Thread.sleep(100);
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} catch (InterruptedException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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}
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} while (!subscriber.isCompleted());
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int count = subscriber.getCounter();
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assertEquals(ITEM_SIZE, count);
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}
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@Test
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public void testReactiveStreamTime() {
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IntStream.range(0, ITEM_SIZE)
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.forEach(item -> publisher.submit(item + ""));
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publisher.close();
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do {
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// wait for subscribers to complete all processing.
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try {
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Thread.sleep(100);
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} catch (InterruptedException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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}
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} while (!subscriber.isCompleted());
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// The runtime in seconds should be equal to the number of items in each batch.
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assertTrue(stopwatch.runtime(TimeUnit.SECONDS) >= (ITEM_SIZE / subscriber.BUFFER_SIZE));
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}
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}
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@ -0,0 +1,100 @@
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package com.baeldung.java9.reactive;
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import static org.junit.Assert.assertEquals;
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import static org.junit.Assert.assertTrue;
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import java.util.concurrent.ForkJoinPool;
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import java.util.concurrent.SubmissionPublisher;
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import java.util.concurrent.TimeUnit;
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import java.util.stream.IntStream;
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import org.junit.Before;
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import org.junit.Rule;
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import org.junit.Test;
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import org.junit.rules.Stopwatch;
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public class BaeldungSubscriberImplTest {
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private static final int ITEM_SIZE = 10;
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private SubmissionPublisher<String> publisher;
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private BaeldungSubscriberImpl<String> subscriber;
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@Before
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public void initialize() {
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// create Publisher with max buffer capacity 3.
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this.publisher = new SubmissionPublisher<String>(ForkJoinPool.commonPool(), 3);
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this.subscriber = new BaeldungSubscriberImpl<String>();
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publisher.subscribe(subscriber);
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}
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@Rule
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public Stopwatch stopwatch = new Stopwatch() {
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};
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@Test
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public void testReactiveStreamCount() {
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IntStream.range(0, ITEM_SIZE)
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.forEach(item -> publisher.submit(item + ""));
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publisher.close();
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do {
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// wait for subscribers to complete all processing.
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try {
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Thread.sleep(100);
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} catch (InterruptedException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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}
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} while (!subscriber.isCompleted());
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int count = subscriber.getCounter();
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assertEquals(ITEM_SIZE, count);
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}
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@Test
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public void testReactiveStreamTime() {
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IntStream.range(0, ITEM_SIZE)
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.forEach(item -> publisher.submit(item + ""));
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publisher.close();
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do {
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// wait for subscribers to complete all processing.
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try {
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Thread.sleep(100);
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} catch (InterruptedException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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}
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} while (!subscriber.isCompleted());
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// The runtime in seconds should be equal to the number of items.
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assertTrue(stopwatch.runtime(TimeUnit.SECONDS) >= ITEM_SIZE);
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}
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@Test
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public void testReactiveStreamOffer() {
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IntStream.range(0, ITEM_SIZE)
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.forEach(item -> publisher.offer(item + "", (subscriber, string) -> {
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// Returning false means this item will be dropped (no retry), if blocked.
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return false;
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}));
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publisher.close();
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do {
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// wait for subscribers to complete all processing.
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try {
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Thread.sleep(100);
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} catch (InterruptedException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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}
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} while (!subscriber.isCompleted());
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int count = subscriber.getCounter();
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// Because 10 items were offered and the buffer capacity was 3, few items will not be processed.
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assertTrue(ITEM_SIZE > count);
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}
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}
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