[Rock-dev] Preventing multiple instances of compositions

[Christian Rauch]

Hello,

we have a simulation composition (AriaSim) using some simulated devices.

If we start this and an additional composition connected to simulated 
devices we get sometimes (not reproducible) this error message:

{{{
Syskit[FATAL]: 
/home/christian/rock_virgo_next/tools/syskit/lib/syskit/network_generation/engine.rb:526:in 
`block (2 levels) in validate_generated_network': device locomotion is 
assigned to both Simulation::MarsActuator{1}:0x69a7f58{driver_dev => 
device(Dev::Simulation::Mars::Actuator, :as => locomotion), conf => 
[locomotion], locomotion_actuators_mappings => [1, 2, 3, 4]}[] and 
Simulation::MarsActuator{1}:0x73ca0a8{driver_dev => 
device(Dev::Simulation::Mars::Actuator, :as => locomotion), conf => 
[locomotion], locomotion_actuators_mappings => [1, 2, 3, 4]}[], but the 
tasks have mismatching inputs (Syskit::SpecError)
}}}

Where locomotion is a simulated devices defined by:
{{{
define_simulated_device("locomotion", Dev::Simulation::Mars::Actuator) 
do |dev|
     ::Simulation::MarsActuator.dispatch('locomotion_actuators', 
(1..4).to_a ).
         use_deployments(/mars_locomotion/).
         with_arguments(dev.arguments).
         with_conf('locomotion')
end
locomotion_dev.period 0.01
}}}

and used in:
{{{
   define 'aria', Virgo::AriaSim.use(
     'actuators' => locomotion_def,
     [...]
   )
}}}

In the network graph (see attached *.dot file) one can see that the 
simulation composition (Virgo::AriaSim) is started twice, and therefore 
also the Simulation::MarsActuator::Cmp.
I guess that is not correct.

It might be, that this problem does not occur when a second composition 
is started accessing a simulated device, but then it happens later when 
a third, ... composition is started.

=> Any ideas why this happens and only happens randomly?


Our guess was to prevent the creation of multiple AriaSim instances by 
setting it as a driver by:
{{{
class AriaSim < Syskit::Composition
     [...]
     driver_for Dev::Platforms::MobileRoboticsSim, :as=>'ariasimdev'
end
}}}

Which results in the error:
{{{
Syskit[FATAL]: cannot find a device to tie to 1 task(s)
Syskit[FATAL]: for Virgo::AriaSim:0x64e5380{}[]
Syskit[FATAL]:   no candidates for Virgo::AriaSim:ariasimdev
Syskit[FATAL]: Engine#resolve failed
}}}

=> So the second question is if a composition could be set as a driver 
and if so, how?

Regards,
Christian


-- 
  Christian Rauch
  Space Robotics

  Universität Bremen
  FB 3 - Mathematik und Informatik
  AG Robotik
  Robert-Hooke-Straße 1
  28359 Bremen, Germany

  Zentrale: +49 421 178 45-6611

  Besuchsadresse der Nebengeschäftstelle:
  Robert-Hooke-Straße 5
  28359 Bremen, Germany

  Tel:     +49 421 178 45-6619
  Empfang: +49 421 178 45-6600
  Fax:     +49 421 178 45-4150
  E-Mail:  Christian.Rauch at dfki.de

  Weitere Informationen: http://www.informatik.uni-bremen.de/robotik

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