[jira] [Created] (CAMEL-8675) Aggregators swallows exceptions

["Jostein Gogstad (JIRA)" <ji...@apache.org>]

Jostein Gogstad created CAMEL-8675:
--------------------------------------

             Summary: Aggregators swallows exceptions
                 Key: CAMEL-8675
                 URL: https://issues.apache.org/jira/browse/CAMEL-8675
             Project: Camel
          Issue Type: Bug
          Components: camel-core
    Affects Versions: 2.12.2
            Reporter: Jostein Gogstad


Processors attached to aggregators can not throw exceptions, they will be swallowed. This makes it impossible to propagate exceptions from camel to, for instance, a CXF endpoint or custom JAX-WS service.

This route and test illustrates the problem:

{code:java|title=AggregatorBug.java}
public class AggregatorBug extends RouteBuilder {

    @Override
    public void configure() throws Exception {
        from("direct:start")
            .routeId(getClass().getSimpleName())
            .aggregate().header("cheese")
            .aggregationStrategy(new GroupedExchangeAggregationStrategy())
            .completionSize(1)
            .process(new Processor() {
                @Override
                public void process(Exchange exchange) throws Exception {
                    throw new RuntimeException();
                }
            });
    }
}
{code}

{code:java|title=AggregatorBugTest.java}
public class AggregatorBugTest extends CamelTestSupport {

    @EndpointInject(uri = "mock:beforeException")
    protected MockEndpoint beforeException;

    @Override
    public boolean isUseAdviceWith() {
        return true;
    }


    @Override
    protected RouteBuilder createRouteBuilder() throws Exception {
        return new AggregatorBug();
    }

    @Override
    protected void doPostSetup() throws Exception {
        context.getRouteDefinition(AggregatorBug.class.getSimpleName()).adviceWith(context, new AdviceWithRouteBuilder() {
            @Override
            public void configure() throws Exception {
                weaveByType(ProcessDefinition.class).before().to("mock:beforeException");
            }
        });
        context.start();
    }

    @Test
    public void exceptions_are_swallowed() throws Exception {
        try {
            template.sendBodyAndHeader("direct:start", 42, "cheese", "foo");
            fail("Expected exception");
        } catch (CamelExecutionException e) {
            beforeException.expectedMessageCount(1);
        }

    }
}
{code}

>From what I can see, the problem is located in [AggregatorProcessor|https://github.com/apache/camel/blob/camel-2.12.x/camel-core/src/main/java/org/apache/camel/processor/aggregate/AggregateProcessor.java#L247] (github link). The output from {{doAggregate}} is ignored, even though it contains the exchange with the exception. The exchanged that is used from here on out is the original input to the route, not the aggregated output. 

The only way I can see that would trigger the exception would be to add a custom errorHandler that re-throwed the exception. Unfortunately this is also impossible. The {{errorHandler}} on {{AggregatorProcessor}} is set in the constructor, and there is no API to set the errorHandler from {{AggregatorDefinition}}. The errorHandler set on the route is also ignored by {{AggregatorProcessor}}.

This problem has been reported earlier in CAMEL-1546. The proposed solution with using a seda route is not satisfactory for cxf endpoints since the calling thread would return.



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