desktop_entries: Reload .desktop on search

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. As a small performance improvement, only trigger this update
on a search event and if the search query is empty.

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.

Author: ljrk0

plugins/src/desktop_entries/mod.rs

@@ -15,7 +15,6 @@ pub(crate) mod utils;
 
 pub async fn main() {
     let mut app = App::new(async_stdout());
-    app.reload().await;
 
     let mut requests = json_input_stream(async_stdin());
 
@@ -25,7 +24,12 @@ pub async fn main() {
                 Request::Activate(id) => app.activate(id).await,
                 Request::ActivateContext { id, context } => app.activate_context(id, context).await,
                 Request::Context(id) => app.context(id).await,
-                Request::Search(query) => app.search(&query).await,
+                Request::Search(query) => {
+                    if query.is_empty() {
+                        app.reload().await;
+                    }
+                    app.search(&query).await;
+                }
                 Request::Exit => break,
                 _ => (),
             },