BAEL-772 Reactive Streams API with Ratpack (#11328)
* [BAEL-4849] Article code * [BAEL-4968] Article code * [BAEL-4968] Article code * [BAEL-4968] Article code * [BAEL-4968] Remove extra comments * [BAEL-4020] Article code * [BAEL-722] Article code
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psevestre
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package com.baeldung.ratpack;
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import org.reactivestreams.Publisher;
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import org.reactivestreams.Subscriber;
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import org.reactivestreams.Subscription;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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// Non-thread safe !!!
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class CompliantPublisher implements Publisher<Integer> {
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String name;
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private static final Logger log = LoggerFactory.getLogger(CompliantPublisher.class);
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private long available;
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public CompliantPublisher(long available) {
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this.available = available;
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}
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@Override
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public void subscribe(Subscriber<? super Integer> subscriber) {
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log.info("subscribe");
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subscriber.onSubscribe(new CompliantSubscription(subscriber));
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}
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private class CompliantSubscription implements Subscription {
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private Subscriber<? super Integer> subscriber;
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private int recurseLevel;
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private long requested;
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private boolean cancelled;
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public CompliantSubscription(Subscriber<? super Integer> subscriber) {
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this.subscriber = subscriber;
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}
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@Override
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public void request(long n) {
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log.info("request: requested={}, available={}", n, available);
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requested += n;
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if ( recurseLevel > 0 ) {
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return;
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}
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recurseLevel++;
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for (int i = 0 ; i < (requested) && !cancelled && available > 0 ; i++, available-- ) {
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subscriber.onNext(i);
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}
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subscriber.onComplete();
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}
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@Override
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public void cancel() {
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cancelled = true;
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}
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}
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}
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@@ -0,0 +1,67 @@
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package com.baeldung.ratpack;
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import java.util.concurrent.CountDownLatch;
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import java.util.concurrent.TimeUnit;
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import org.reactivestreams.Subscriber;
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import org.reactivestreams.Subscription;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class LoggingSubscriber<T> implements Subscriber<T> {
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private static final Logger log = LoggerFactory.getLogger(LoggingSubscriber.class);
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private Subscription subscription;
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private long requested;
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private long received;
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private CountDownLatch finished = new CountDownLatch(1);
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@Override
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public void onComplete() {
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log.info("onComplete: sub={}", subscription.hashCode());
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finished.countDown();
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}
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@Override
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public void onError(Throwable t) {
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log.error("Error: sub={}, message={}", subscription.hashCode(), t.getMessage(),t);
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finished.countDown();
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}
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@Override
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public void onNext(T value) {
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log.info("onNext: sub={}, value={}", subscription.hashCode(), value);
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this.received++;
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this.requested++;
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subscription.request(1);
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}
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@Override
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public void onSubscribe(Subscription sub) {
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log.info("onSubscribe: sub={}", sub.hashCode());
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this.subscription = sub;
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this.received = 0;
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this.requested = 1;
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sub.request(1);
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}
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public long getRequested() {
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return requested;
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}
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public long getReceived() {
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return received;
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}
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public void block() {
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try {
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finished.await(10, TimeUnit.SECONDS);
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}
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catch(InterruptedException iex) {
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throw new RuntimeException(iex);
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}
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}
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}
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@@ -0,0 +1,46 @@
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package com.baeldung.ratpack;
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import org.reactivestreams.Publisher;
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import org.reactivestreams.Subscriber;
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import org.reactivestreams.Subscription;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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public class NonCompliantPublisher implements Publisher<Integer> {
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private static final Logger log = LoggerFactory.getLogger(NonCompliantPublisher.class);
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@Override
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public void subscribe(Subscriber<? super Integer> subscriber) {
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log.info("subscribe");
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subscriber.onSubscribe(new NonCompliantSubscription(subscriber));
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}
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private class NonCompliantSubscription implements Subscription {
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private Subscriber<? super Integer> subscriber;
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private int recurseLevel = 0;
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public NonCompliantSubscription(Subscriber<? super Integer> subscriber) {
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this.subscriber = subscriber;
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}
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@Override
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public void request(long n) {
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log.info("request: n={}", n);
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if ( recurseLevel > 0 ) {
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return;
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}
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recurseLevel++;
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for (int i = 0 ; i < (n + 5) ; i ++ ) {
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subscriber.onNext(i);
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}
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subscriber.onComplete();
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}
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@Override
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public void cancel() {
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}
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}
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}
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@@ -0,0 +1,140 @@
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package com.baeldung.ratpack;
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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.time.Duration;
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import java.util.Arrays;
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import java.util.List;
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import java.util.concurrent.Executors;
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import java.util.concurrent.ScheduledExecutorService;
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import org.junit.jupiter.api.Test;
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import org.reactivestreams.Publisher;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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import ratpack.exec.ExecResult;
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import ratpack.func.Action;
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import ratpack.stream.StreamEvent;
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import ratpack.stream.Streams;
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import ratpack.stream.TransformablePublisher;
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import ratpack.test.exec.ExecHarness;
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public class RatpackStreamsUnitTest {
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private static Logger log = LoggerFactory.getLogger(RatpackStreamsUnitTest.class);
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@Test
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public void whenPublish_thenSuccess() {
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Publisher<String> pub = Streams.publish(Arrays.asList("hello", "hello again"));
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LoggingSubscriber<String> sub = new LoggingSubscriber<String>();
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pub.subscribe(sub);
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sub.block();
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}
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@Test
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public void whenYield_thenSuccess() {
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Publisher<String> pub = Streams.yield((t) -> {
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return t.getRequestNum() < 5 ? "hello" : null;
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});
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LoggingSubscriber<String> sub = new LoggingSubscriber<String>();
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pub.subscribe(sub);
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sub.block();
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assertEquals(5, sub.getReceived());
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}
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@Test
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public void whenPeriodic_thenSuccess() {
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ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
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Publisher<String> pub = Streams.periodically(executor, Duration.ofSeconds(1), (t) -> {
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return t < 5 ? String.format("hello %d",t): null;
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});
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LoggingSubscriber<String> sub = new LoggingSubscriber<String>();
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pub.subscribe(sub);
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sub.block();
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assertEquals(5, sub.getReceived());
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}
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@Test
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public void whenMap_thenSuccess() throws Exception {
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TransformablePublisher<String> pub = Streams.yield( t -> {
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return t.getRequestNum() < 5 ? t.getRequestNum() : null;
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})
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.map(v -> String.format("item %d", v));
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ExecResult<List<String>> result = ExecHarness.yieldSingle((c) -> pub.toList() );
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assertTrue("should succeed", result.isSuccess());
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assertEquals("should have 5 items",5,result.getValue().size());
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}
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@Test
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public void whenNonCompliantPublisherWithBuffer_thenSuccess() throws Exception {
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TransformablePublisher<Integer> pub = Streams.transformable(new NonCompliantPublisher())
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.wiretap(new LoggingAction("before buffer"))
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.buffer()
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.wiretap(new LoggingAction("after buffer"))
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.take(1);
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LoggingSubscriber<Integer> sub = new LoggingSubscriber<>();
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pub.subscribe(sub);
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sub.block();
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}
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@Test
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public void whenNonCompliantPublisherWithoutBuffer_thenSuccess() throws Exception {
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TransformablePublisher<Integer> pub = Streams.transformable(new NonCompliantPublisher())
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.wiretap(new LoggingAction(""))
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.take(1);
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LoggingSubscriber<Integer> sub = new LoggingSubscriber<>();
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pub.subscribe(sub);
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sub.block();
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}
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@Test
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public void whenCompliantPublisherWithoutBatch_thenSuccess() throws Exception {
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TransformablePublisher<Integer> pub = Streams.transformable(new CompliantPublisher(10))
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.wiretap(new LoggingAction(""));
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LoggingSubscriber<Integer> sub = new LoggingSubscriber<>();
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pub.subscribe(sub);
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sub.block();
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}
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@Test
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public void whenCompliantPublisherWithBatch_thenSuccess() throws Exception {
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TransformablePublisher<Integer> pub = Streams.transformable(new CompliantPublisher(10))
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.wiretap(new LoggingAction("before batch"))
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.batch(5, Action.noop())
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.wiretap(new LoggingAction("after batch"));
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LoggingSubscriber<Integer> sub = new LoggingSubscriber<>();
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pub.subscribe(sub);
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sub.block();
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}
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private static class LoggingAction implements Action<StreamEvent<Integer>>{
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private final String label;
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public LoggingAction(String label) {
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this.label = label;
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}
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@Override
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public void execute(StreamEvent<Integer> e) throws Exception {
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log.info("{}: event={}", label,e);
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}
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}
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}
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