SSE: Reactive SseEventSource client doesn't consume empty events

[sdaschner]

Describe the bug

When using quarkus-rest-client-reactive-*, InboundSseEvents with an empty data block aren't consumed by the SseEventSource. Using quarkus-rest-client-* (without reactive) solves this.

Expected behavior

No response

Actual behavior

No response

How to Reproduce?

Assuming you have the following SSE stream:

curl localhost:8080/updates -i
HTTP/1.1 200 OK
Content-Type: text/event-stream
transfer-encoding: chunked



event: VALIDATED
data: {"test":"123"}

event: STARTED
data: {"test":"234"}

event: UPDATED
data:

event: STOPPED
data:

With quarkus-rest-client-reactive-jsonb, the following test results in only two consumed events:

@Test
void test() {
    Client client = ClientBuilder.newClient();

    WebTarget target = client.target("http://localhost:8080/updates");
    SseEventSource eventSource = SseEventSource.target(target).build();

    eventSource.register(ev -> {
        System.out.println("ev.isEmpty() = " + ev.isEmpty());
        System.out.println("event: " + ev.getName() + " " + ev.readData());
    }, thr -> {
        thr.printStackTrace();
    });

    eventSource.open();

    System.out.println("opened");
    LockSupport.parkNanos(200_000_000_000L);

    eventSource.close();
    client.close();
}

Result:

opened
ev.isEmpty() = false
event: VALIDATED {"test":"123"}
ev.isEmpty() = false
event: STARTED {"test":"234"}

With quarkus-rest-client-jsonb, all the events show up as expected:

opened
ev.isEmpty() = false
event: VALIDATED {"test":"123"}
ev.isEmpty() = false
event: STARTED {"test":"234"}
ev.isEmpty() = true
event: UPDATED
ev.isEmpty() = true
event: STOPPED

Output of uname -a or ver

No response

Output of java -version

No response

GraalVM version (if different from Java)

No response

Quarkus version or git rev

3.2.0.Final

Build tool (ie. output of mvnw --version or gradlew --version)

No response

Additional information

No response

[quarkus-bot]

/cc @cescoffier (rest-client)

[geoand]

Thanks for reporting!

Any chance you can upload a small sample that reproduces the described behavior?

[sdaschner]

Sure, added a branch: https://github.com/sdaschner/quarkus-playground/tree/sse-issue-35966

To reproduce:

git clone # with branch https://github.com/sdaschner/quarkus-playground/tree/sse-issue-35967
cd .../server/
mvn quarkus:dev

# new terminal
cd .../client/
mvn clean package
java -jar target/quarkus-app/quarkus-run.jar

When switching the pom to use -reactive, the result shows fewer events.

[geoand]

Thanks!

#35990 fixes the behavior of quarkus-rest-client-reactive