Improve handling of xhprof_prepend.php

[tyler36]

The default xhpro_prepend.php file that ships with recent flavors of DDEV is NOT compatible with this addon.

Currently, we take ownership of it so this addon can function. However, we don't return ownership. This could cause problems if the addon is removed or disabled.

This PR offers a different approach.

• use post-start hook to claim ownership.
• use pre-stop hook to return ownership.

This handles ownership while the addon is active.
But returns ownership when stop; thus DDEV will return to "default" state next time it checks the file.

Fixes #11

[deviantintegral]

Great idea! 👏

[rfay]

Minor changes, suggesting cp if that is easy for you.

Overall, I'm still not even happy that we mount the prepend file and think we should be doing something better in DDEV rather than working around it. But here we are, so this approach is definitely an improvement.

[rfay]

This line would be easier to understand if it were just the traditional EOF or maybe PHP_EOF. Caught me by surprise. Not that important of course.

[rfay]

Wouldn't it be easier to use a cp here instead of cat? Then it's also one line.

[rfay]

Same, wouldn't cp be easier?

[rfay]

If you use cp you'd still have this, it would just be indirectly installed.

[tyler36]

Wouldn't it be easier to use a cp here instead of cat? Then it's also one line.

The idea here was to avoid copying a file. I want to dynamically write out it.

Because the file contents contains #ddev-generated , I couldn't figure out how to escape the hash using echo.
Instead, I went with HEREDOC syntax. The output file contains documentation that makes it more understandable about what the file does and how it behaves.

If we went with cp, we would copy over a file (so we now how 2 files, our temp fake and the replace xhprof_prepend.php).
What about pre-stop hook? Writing #ddev-generate cause DDEV to replace the file with it's default on start up (see #29 (comment)) so we could keep it pre-stop here.
I not sure about using cp here, would that be another file to copy over?

[rfay]

I think you should go ahead with this. It can be adjusted in the future.

Another technique is to use something like #xhgui-generated in the text of the prepend file, and feel free to delete it (using removal_actions) if it contains that. if grep '#xhgui-generated' <phpfile>; then rm <phpfile>; fi

[tyler36]

Rebased.