fix(cmd/main.go): add a channel to proc{} for detecting SIGINT

[johnrichardrinehart]

Fixes #209

Description

This is a solution to fix the usability problem described in #209.

Please provide any suggestions to improve the code quality. Thank you.

[dnephin]

Thank you for raising this issue and opening a PR to fix it!

Your changes were a great start. I had to make a few changes to get it to work:

• replaced the channel with an in32 that is accessed atomically. We don't need coordination here, so the atomic int seems like it should work well without having to deal with reading from a channel that could be empty
• changed startGoTest to return a pointer to a proc, so that the caller would be reading the same field as the signal handler function.
• changed main() to accept an exit code from any error, instead of only from an exec.ExitError.
• add 128 to the signal number to match bash (https://tldp.org/LDP/abs/html/exitcodes.html)

This seems to work for me, let me know if it is also working for you.

[johnrichardrinehart]

@dnephin Awesome! Happy you considered my PR. Please give me 24 hours to review.

One question, to start: Did my code fail to compile/execute, for you? I compiled and executed in my fork prior to submitting the PR.

I'm confused why the atomic load-store was necessary, but I trust that it was. Would you please explain this to me? I figured my channel solution would handle synchronization/races.

I just re-read your comment. I think the atomic load-store is a much better semantic than a signal channel. Good job!

I love that you found the bash section on exit codes and applied it correctly. Thanks!

Thanks for taking the time to clean this up. I fully expected some revisions, so I'm happy to see your commits :) .

[dnephin]

One question, to start: Did my code fail to compile/execute, for you?

Ya, my comment was misleading I think. I believe it did work, but it felt to me like the atomic was going to be slightly safer and easier to work with.

Thanks again for raising this issue and getting it fixed!