Added CommandWrapLauncher to easily append/prepend to launch commands.

[johannesbulin]

Description

Added a CommandWrapLauncher that basically appends or prepends some additional flags/commands to the launch command.

Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

[Copilot]

Pull request overview

This PR introduces a new ComposeLauncher wrapper to modify an existing launcher’s final command by prepending and/or appending additional command fragments, and adds tests to validate the wrapper’s behavior across supported launchers and environment setups.

Changes:

• Added ComposeLauncher (LauncherWrapper) that rewrites LaunchData.cmd as: prepend_flags + base_cmd + flags + append_flags.
• Exported the new launcher wrapper from ifsbench.launch.
• Added parametrized tests covering run_dir, env, and cmd behavior for the wrapper.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.

File	Description
ifsbench/launch/composelauncher.py	Adds the new ComposeLauncher wrapper that composes command lists around an existing prepared command.
ifsbench/launch/__init__.py	Exposes ComposeLauncher as part of the ifsbench.launch public API.
ifsbench/launch/tests/test_composelauncher.py	Adds sanity tests validating that wrapping preserves run_dir/env and composes cmd as intended.

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[codecov]

Codecov Report

❌ Patch coverage is 97.72727% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 92.20%. Comparing base (96eddfe) to head (f9b7169).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
ifsbench/launch/commandoverride.py	92.30%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #111      +/-   ##
==========================================
+ Coverage   91.90%   92.20%   +0.29%     
==========================================
  Files          77       81       +4     
  Lines        4495     4706     +211     
==========================================
+ Hits         4131     4339     +208     
- Misses        364      367       +3     

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

[johannesbulin]

@awnawab : This would give you a rather easy way to append/prepend flags/commands to a launch command, so

mpirun -n <automatically_set> command

would become

<prepend_flags> mpirun -n <automatically_set> command <append_flags>

Is this what you want? Or do you need something that appends/prepends to the actual command that you want to launch, for example to transform

mpirun -n <automatically_set> my_command

to

mpirun -n <automatically_set> valgrind --track-origin my_command

[awnawab]

More the latter. I can't think of a use case for prepend_flags, and am mainly looking for a hook to add in debugger/profiler invocations.

[johannesbulin]

More the latter. I can't think of a use case for prepend_flags, and am mainly looking for a hook to add in debugger/profiler invocations.

Thanks! I'll try to work on a solution for this!

[johannesbulin]

Hi @awnawab ,

I've added a CommandWrapOverride. To use it, you can use a custom launcher YAML file like this:

cat > launcher_config.yaml << EOF

class_name: CompositeLauncher
flags: []
base_launcher:
  class_name: SrunLauncher
  flags: []
command_overrides:
- class_name: CommandWrapOverride
  prepend_cmd: ['valgrind', '--trace-children=yes']

EOF

ifsbench_run.py ... --launcher-config=launcher_config.yaml

Is this what you need?

[awnawab]

Yes this is exactly what I was after, thanks! In fact, the BashLauncher that you showed me offline is probably an even better way of achieving the above. Both are valid solutions for my purposes, I'll let you decide whether you want to support one or both. Many thanks again for looking into this 🙏