desktop_entries: Reload .desktop on search

[ljrk0]

Since pop-launcher has been demonized, the desktop_entries plugin isn't relaunched on every search anymore. In consequence, it is not providing up-to-date results when .desktop files have changed (e.g., on un-/installation of a new application) anymore.

Move the app.reload() call into the request loop to trigger a re-index. In a release-build this has been fine performance wise on an 8th Gen i5 laptop device.

Alternatives could include remembering the last time the index was built (initialised to UNIX_EPOCH before the loop) and only conditionally triggering a re-index after a hot-period of 10s since the last run. In our testing this didn't result in any noticeable difference.

NOTE: This has been tested against commit fca3b25 but builds against master too. However, master error'ed with unrelated issues regarding the parsing of CLI arguments.

[mmstick]

It'd be better to reload only on an empty search query

[ljrk0]

Implemented the requested change + rebased ontop of master, but I cannot reproduce the issue since #270 got merged(?). At least not on fedora with ryan's copr pop-launcher package (nightly).

The new behavior seems that the desktop_entries plugin doesn't reload the .desktop entries anymore, so this behavior is still the same as before:

$ /usr/libexec/pop-launcher/plugins/desktop_entries/desktop-entries
# now install vlc
{ "Search": "vlc" }
# doesn't find vlc

But it seems that the pop-launcher now does some magic to fix this when actually running the launcher itself?

If I understand this correctly, then this PR can be closed?

[wiiznokes]

iirc, a plugin will only be "demonized" when they have long_lived in their manifest (ex: cosmic_toplevel, https://github.com/pop-os/launcher/blob/master/plugins/src/cosmic_toplevel/plugin.ron#L7).
So, the desktop_entries plugin will be reloaded every time cosmic-launcher is shown.

[wiiznokes]

You could also add a watcher on the .desktop dirs. Idk if its better performance wise