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new d48f15e188de CAMEL-25350: camel-reactive-streams - complete the
exchanges of a batch that the subscriber cancels before they are sent (#27470)
d48f15e188de is described below
commit d48f15e188decfc9a22bfead1fc67ee356c4a423
Author: allthingssecurity <[email protected]>
AuthorDate: Wed Oct 7 13:39:54 2026 +0530
CAMEL-25350: camel-reactive-streams - complete the exchanges of a batch
that the subscriber cancels before they are sent (#27470)
Co-Authored-By: Claude Opus 5.5 <[email protected]>
---
.../reactive/streams/engine/CamelSubscription.java | 18 ++-
.../reactive/streams/CancelSubscriptionTest.java | 141 +++++++++++++++++++++
2 files changed, 156 insertions(+), 3 deletions(-)
diff --git
a/components/camel-reactive-streams/src/main/java/org/apache/camel/component/reactive/streams/engine/CamelSubscription.java
b/components/camel-reactive-streams/src/main/java/org/apache/camel/component/reactive/streams/engine/CamelSubscription.java
index b9ecad2e2735..f1d647d113c5 100644
---
a/components/camel-reactive-streams/src/main/java/org/apache/camel/component/reactive/streams/engine/CamelSubscription.java
+++
b/components/camel-reactive-streams/src/main/java/org/apache/camel/component/reactive/streams/engine/CamelSubscription.java
@@ -99,12 +99,20 @@ public class CamelSubscription implements Subscription {
LOG.debug("Requested {} events from subscriber", l);
if (l <= 0) {
// wrong argument
+ List<Exchange> bufferCopy;
mutex.lock();
- terminated = true;
- mutex.unlock();
+ try {
+ terminated = true;
+ bufferCopy = new LinkedList<>(buffer);
+ buffer.clear();
+ } finally {
+ mutex.unlock();
+ }
publisher.unsubscribe(this);
subscriber.onError(new IllegalArgumentException("3.9"));
+ // the subscription is terminated: the buffered exchanges are
discarded as on cancel()
+ discardBuffer(bufferCopy);
} else {
mutex.lock();
requested += l;
@@ -175,7 +183,8 @@ public class CamelSubscription implements Subscription {
if (sendingQueue != null) {
LOG.debug("Sending {} events to the subscriber",
sendingQueue.size());
- for (Exchange data : sendingQueue) {
+ Exchange data;
+ while ((data = sendingQueue.poll()) != null) {
// TODO what if the subscriber throws an exception?
this.subscriber.onNext(data);
@@ -184,6 +193,9 @@ public class CamelSubscription implements Subscription {
mutex.unlock();
if (shouldStop) {
+ // the subscription was cancelled: the exchanges taken
from the buffer
+ // but not sent must be discarded like the ones left in
the buffer
+ discardBuffer(sendingQueue);
break;
}
}
diff --git
a/components/camel-reactive-streams/src/test/java/org/apache/camel/component/reactive/streams/CancelSubscriptionTest.java
b/components/camel-reactive-streams/src/test/java/org/apache/camel/component/reactive/streams/CancelSubscriptionTest.java
new file mode 100644
index 000000000000..d43d2f8ecfbf
--- /dev/null
+++
b/components/camel-reactive-streams/src/test/java/org/apache/camel/component/reactive/streams/CancelSubscriptionTest.java
@@ -0,0 +1,141 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.component.reactive.streams;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.camel.Exchange;
+import org.apache.camel.builder.RouteBuilder;
+import org.apache.camel.component.reactive.streams.api.CamelReactiveStreams;
+import org.apache.camel.component.reactive.streams.engine.CamelSubscription;
+import org.junit.jupiter.api.Test;
+import org.reactivestreams.Subscriber;
+import org.reactivestreams.Subscription;
+
+import static org.awaitility.Awaitility.await;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class CancelSubscriptionTest extends BaseReactiveTest {
+
+ @Test
+ void testCancelInOnNextCompletesTheOtherExchanges() throws Exception {
+ TestSubscriber subscriber = new TestSubscriber(true);
+
CamelReactiveStreams.get(context).fromStream("numbers").subscribe(subscriber);
+ await().atMost(5, TimeUnit.SECONDS).until(() ->
subscriber.subscription != null);
+
+ List<CompletableFuture<Exchange>> sent =
sendAndWaitBuffered(subscriber, 3);
+
+ // the subscriber takes the three exchanges at once and cancels when
it sees the first one
+ subscriber.subscription.request(3);
+
+ for (int i = 0; i < sent.size(); i++) {
+ CompletableFuture<Exchange> future = sent.get(i);
+ int n = i + 1;
+ await().atMost(5, TimeUnit.SECONDS)
+ .untilAsserted(() -> assertTrue(future.isDone(), "Exchange
" + n + " never completed"));
+ }
+ assertEquals(List.of(1), subscriber.received);
+ assertNull(sent.get(0).get().getException());
+ assertInstanceOf(IllegalStateException.class,
sent.get(1).get().getException());
+ assertInstanceOf(IllegalStateException.class,
sent.get(2).get().getException());
+ }
+
+ @Test
+ void testNonPositiveRequestCompletesTheBufferedExchanges() throws
Exception {
+ TestSubscriber subscriber = new TestSubscriber(false);
+
CamelReactiveStreams.get(context).fromStream("numbers").subscribe(subscriber);
+ await().atMost(5, TimeUnit.SECONDS).until(() ->
subscriber.subscription != null);
+
+ List<CompletableFuture<Exchange>> sent =
sendAndWaitBuffered(subscriber, 2);
+
+ // a request of 0 terminates the subscription with an error (rule 3.9
of the specification)
+ subscriber.subscription.request(0);
+
+ assertInstanceOf(IllegalArgumentException.class, subscriber.error);
+ for (CompletableFuture<Exchange> future : sent) {
+ await().atMost(5, TimeUnit.SECONDS)
+ .untilAsserted(() -> assertTrue(future.isDone(), "A
buffered exchange never completed"));
+ assertInstanceOf(IllegalStateException.class,
future.get().getException());
+ }
+ assertEquals(List.of(), subscriber.received);
+ }
+
+ private List<CompletableFuture<Exchange>>
sendAndWaitBuffered(TestSubscriber subscriber, int count) {
+ List<CompletableFuture<Exchange>> sent = new ArrayList<>();
+ for (int i = 1; i <= count; i++) {
+ int n = i;
+ sent.add(template.asyncSend("direct:numbers", e ->
e.getIn().setBody(n)));
+ // the subscriber has requested nothing yet, so the exchange stays
in the buffer of its subscription
+ await().atMost(5, TimeUnit.SECONDS)
+ .until(() -> ((CamelSubscription)
subscriber.subscription).getBufferSize() == n);
+ }
+ return sent;
+ }
+
+ @Override
+ protected RouteBuilder createRouteBuilder() {
+ return new RouteBuilder() {
+ @Override
+ public void configure() {
+ from("direct:numbers")
+ .to("reactive-streams:numbers");
+ }
+ };
+ }
+
+ private static final class TestSubscriber implements Subscriber<Exchange> {
+
+ private final boolean cancelOnFirst;
+ private final List<Integer> received = new CopyOnWriteArrayList<>();
+ private volatile Subscription subscription;
+ private volatile Throwable error;
+
+ private TestSubscriber(boolean cancelOnFirst) {
+ this.cancelOnFirst = cancelOnFirst;
+ }
+
+ @Override
+ public void onSubscribe(Subscription subscription) {
+ this.subscription = subscription;
+ }
+
+ @Override
+ public void onNext(Exchange exchange) {
+ received.add(exchange.getIn().getBody(Integer.class));
+ if (cancelOnFirst) {
+ subscription.cancel();
+ }
+ }
+
+ @Override
+ public void onError(Throwable throwable) {
+ this.error = throwable;
+ }
+
+ @Override
+ public void onComplete() {
+ // noop
+ }
+ }
+}
