fix concurrent service calls, add test

[LeroyR]

Test/fix attempt for #261

[msmcconnell]

Thanks for taking a shot at that Issue.
I tried running the test but I still got some mismatched result values.

Feb 23, 2018 11:04:52 AM org.ros.internal.node.RosoutLogger info
    INFO: 
    Request: 0+0 Result: 0

    Feb 23, 2018 11:04:52 AM org.ros.internal.node.RosoutLogger info
    INFO: 
    Request: 2+2 Result: 2

    Feb 23, 2018 11:04:52 AM org.ros.internal.node.RosoutLogger info
    INFO: 
    Request: 6+6 Result: 8

    Feb 23, 2018 11:04:52 AM org.ros.internal.node.RosoutLogger info
    INFO: 
    Request: 4+4 Result: 12


    Feb 23, 2018 11:04:52 AM org.ros.internal.node.RosoutLogger info
    INFO: 
    Request: 9+9 Result: 16

Were you able to run this test successfully?
Maybe one of the regular contributors can provide some insights on what your solution is failing to address.

[jubeira]

Thanks for kicking this off @LeroyR @msmcconnell.

I'll take a look when I have some time; apparently this could be a first step but something else is missing there.

/cc @drigz

[LeroyR]

Yes, it just randomly worked once. I think there is currently no way to preserve ordering if we call the service multiple times with the same client. Was searching for a issue we had where sometimes no handler was registered, my branch had debug prints that (of course) then 'fixed' the ordering

close this PR