davsclaus commented on code in PR #28069:
URL: https://github.com/apache/camel/pull/28069#discussion_r4310716140
##########
components/camel-coap/src/main/java/org/apache/camel/coap/CoAPObserver.java:
##########
@@ -63,13 +65,67 @@ public void onLoad(CoapResponse response) {
}
}
+ @Override
+ protected void doStop() throws Exception {
+ // cancel the observation, or the server keeps sending notifications
to this consumer after it was stopped, and
+ // a route that is started again then gets every notification twice
(once from the stopped consumer)
+ Observation current = observation;
+ observation = null;
+ if (current != null) {
+ current.cancel();
+ }
+ if (client != null) {
+ client.shutdown();
+ client = null;
+ }
+ super.doStop();
+ }
+
@Override
public void onError() {
getExceptionHandler().handleException(new IOException("CoAP request
timed out or has been rejected by the server"));
- startObserve();
+ if (isRunAllowed()) {
+ startObserve();
+ }
}
private void startObserve() {
- this.client.observe(this);
+ Observation next = new Observation();
+ this.observation = next;
+ next.relation = this.client.observe(next);
+ }
Review Comment:
A lock-free alternative to the lock: read `client` once, and check again
after the relation is set. `doStop()` runs after the status became STOPPING,
and both `status` and `observation`/`relation`/`cancelled` are volatile. So
either `doStop()` sees this observation with its relation set, or this check
sees `!isRunAllowed()` / `cancelled` and cancels it. `proactiveCancel()` is
CAS-guarded, so a double cancel is harmless.
```suggestion
private void startObserve() {
CoapClient current = this.client;
if (current == null) {
return;
}
Observation next = new Observation();
this.observation = next;
next.relation = current.observe(next);
if (next.cancelled || !isRunAllowed()) {
// doStop() ran while this observation was being set up
next.cancel();
}
}
```
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