Is it the designed and desired behavior that makes Camel routes to not execute onCompletion tasks in a pipeline with several SEDA queues? - apache-camel

Question

I stumbled upon a problem with not working onCompletion between the routes that pass a message over SEDA queues.
The route configuration is similar to this simplified version:
from("direct:a")
.onCompletion().log("a - done").end()
.to("seda:b");
from("seda:b")
.onCompletion().log("b - done").end()
.to("seda:c");
from("seda:c")
.onCompletion().log("c - done").end()
.to("seda:d");
from("seda:d")
.onCompletion().log("d - done").end()
.to("mock:end");
With this configuration, I get only "d - done" logging.
I debugged the execution and noticed that the onCompletion handler from "a", "b", and "c" don't get executed because they are route-scoped and get attempted to be executed in the scope of the next route.
This happens because they get handed over from the initial exchange to an exchange prepared for the next route. It happens in the SedaProducer::addToQueue method with copy parameter defined as true, which makes the ::prepareCopy method being called, which in its turn calls ExchangeHelper.createCorrelatedCopy with handover defined as true.
It seems to me like a bug, because looking at the routes configuration I'd expect different behavior: all the onCompletion tasks get executed reporting on routes finalization. Though maybe I'm missing something here, and if this is the case then I would appreciate you guys helping me to find out the missing details.

Answer 1

The workaround I implemented is ugly but does the trick. Before sending to the next route (queue) we hand over completions to a holder exchange and after sending we hand over them back from the holder.
Here is a code example:
route
.process(exchange -> {
var holder = new DefaultExchange(exchange.getContext());
exchange.adapt(ExtendedExchange.class).handoverCompletions(holder);
exchange.setProperty(SYNC_HOLDER_PROPERTY, holder);
})
.to("seda://next")
.process(exchange -> exchange
.getProperty(SYNC_HOLDER_PROPERTY, ExtendedExchange.class)
.handoverCompletions(exchange));