Re: [PATCH] Speedup bash completion loading

On Mon, Oct 05, 2009 at 08:25:04AM -0700, Shawn O. Pearce wrote:

Kirill Smelkov [off-list ref] wrote:

quoted

I've tracked down that the most time is spent warming up merge_strategy,
all_command & porcelain_command caches.

Nak.

The problem is, during completion when we modify the value the
change doesn't persist beyond the current completion invocation.
Thus there is no value in the cache, so every completion attempt
which needs the list has to rerun the command to compute it.

Yes, my mistake.

To avoid spawning subshell on $(__git_porcelain_commands) I could come up
with "caching" at the upper level, as e.g.

@@ -2107,7 +2111,10 @@ _git ()
                        --help
                        "
                        ;;
-               *)     __gitcomp "$(__git_porcelain_commands) $(__git_aliases)" ;;
+               *)     __gitcomp "
+                       ${__git_porcelain_commandlist:=$(__git_porcelain_commands)}
+                       $(__git_aliases)
+                       " ;;

but that's ugly and not maintainable since e.g. __git_all_commands() is used in
several places.


The other possibility is to pregenerate all these lists at git build time, but
are we going to do it for things under contrib/ ?


This could have easy solution if bash provided analog of $() to call a function
and obtain either its stdout or return value without spawning subshell, but up
to now I could not find such a construct in bash's man.

I have to go, but I'll try to come up with something practical in several days.


Thanks for spotting it,
Kirill