perform environment calculation in Python

[dirk-thomas]

Changes the prefix-level local_setup files in a similar way as colcon/colcon-core#209.

Related to ros2/ros2#764.

[dirk-thomas]

Ready for review.

To test this you need a workspace built with --merge-install since the ament_package setup files don't support isolation (as they are only used for the Debian packages). A nightly archive should work too.

1. Measure the time the following command takes in fresh shell: time . <ws>/install/local_setup.<ext> (also convince yourself that the environment is setup correctly).

2. Two steps:

   • This needs the workspace being sourced. Clone ros_workspace somewhere and switch to the dirk-thomas/support-develop-ament_package branch. Create a build diretory within and build and install into the workspace from 1.:

     cmake .. -DCMAKE_INSTALL_PREFIX=<ws>/install
     make install
     

     This will overwrite the setup files with the state is available in the Dashing Debian packages.

   • Now time again in a fresh shell (again convince yourself that the environment is setup correctly).

3. Two steps again:

   • Switch the ament_package in the workspace to the branch of this PR. If you are not using symlink install build the package with colcon.
   • Repeat the cmake / make install step from 2.
   • Check the timing again in a fresh shell (and as always convince yourself that the environment is setup correctly).

When sharing results please include the platform, the # of packages in your workspace, the extension you sourced as well as the three timings. Thanks.

---

Ubuntu Bionic, ~100 pkgs, bash:

real	0m0.283s
user	0m0.244s
sys	0m0.040s

real	0m0.987s
user	0m0.860s
sys	0m0.188s

real	0m0.163s
user	0m0.131s
sys	0m0.031s

[clalancette]

Ubuntu Bionic, ~300 packages, bash:

real	0m0.625s
user	0m0.344s
sys	0m0.088s

real	0m1.570s
user	0m0.476s
sys	0m0.136s

real	0m0.342s
user	0m0.300s
sys	0m0.032s

[cottsay]

Fedora 30, ~300 packages, bash:

real	0m0.173s
user	0m0.142s
sys	0m0.030s

real	0m0.292s
user	0m0.246s
sys	0m0.048s

real	0m0.169s
user	0m0.134s
sys	0m0.035s

After step 2, I got a bunch of "Failed to load entry point" messages running the ros2 command. After completing step 3, the messages were no longer present and ros2 functioned as expected.

Failed to load entry point 'run': No module named 'ros2pkg'
Failed to load entry point 'test': No module named 'domain_coordinator'
Failed to load entry point 'security': No module named 'ament_index_python'
Failed to load entry point 'launch': No module named 'ament_index_python'
Failed to load entry point 'info': No module named 'ament_index_python'
...

[jacobperron]

Ubuntu Bionic, ~280 packages, zsh:

I'm re-doing parts 1 and 2 (since I think I messed it up the first time).

For 3. I get an error when sourcing, but the environment seems okay:

$ time (. install/local_setup.zsh;)
_opensplice_prepend_unique_value:14: command not found: ament_zsh_to_array
( . install/local_setup.zsh; )  0.19s user 0.03s system 91% cpu 0.244 total

[dirk-thomas]

For 3. I get an error when sourcing, but the environment seems okay:

Please see ros2/rosidl_typesupport_connext#36 and ros2/rosidl_typesupport_opensplice#43 which should fix this by not relying on the presence of the ament_zsh_to_array function.

[jacobperron]

Please see ros2/rosidl_typesupport_connext#36 and ros2/rosidl_typesupport_opensplice#43 which should fix this by not relying on the presence of the ament_zsh_to_array function.

Resolves the error for me.

( . install/local_setup.zsh; )  0.15s user 0.09s system 41% cpu 0.593 total

( . install/local_setup.zsh; )  0.74s user 0.23s system 89% cpu 1.087 total

( . install/local_setup.zsh; )  0.16s user 0.05s system 87% cpu 0.247 total