git-gui: Change our initial GC hint to be an estimate

Instead of running a full git-count-objects to count all of the loose
objects we can get a reasonably close approximation by counting the
number of files in the .git/objects/42 subdirectory. This works out
reasonably well because the SHA-1 hash has a fairly even distribution,
so every .git/objects/?? subdirectory should get a relatively equal
number of files.  If we have at least 8 files in .git/objects/42 than it
is very likely there is about 8 files in every other directory, leaving
us with around 2048 loose objects.

This check is much faster, as we need to only perform a readdir of
a single directory, and we can do it directly from Tcl and avoid the
costly fork+exec.

All of the credit on how clever this is goes to Linus Torvalds; he
suggested using this trick in a post commit hook to repack every so
often.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

diff --git a/git-gui.sh b/git-gui.sh
index 5ca946a184f0b015ed6bd77f0f071a2cbc6251ff..cd2b09372308e5ab6459920f682e66cb61c7b5df 100755 (executable)
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -2560,12 +2560,21 @@ if {[is_enabled transport]} {
 # -- Only suggest a gc run if we are going to stay running.
 #
 if {[is_enabled multicommit]} {
-       set object_limit 2000
-       if {[is_Windows]} {set object_limit 200}
-       regexp {^([0-9]+) objects,} [git count-objects] _junk objects_current
+       set object_limit 8
+       if {[is_Windows]} {
+               set object_limit 1
+       }
+       set objects_current [llength [glob \
+               -directory [gitdir objects 42] \
+               -nocomplain \
+               -tails \
+               -- \
+               *]]
        if {$objects_current >= $object_limit} {
+               set objects_current [expr {$objects_current * 256}]
+               set object_limit    [expr {$object_limit    * 256}]
                if {[ask_popup \
-                       "This repository currently has $objects_current loose objects.
+                       "This repository currently has approximately $objects_current loose objects.
 
 To maintain optimal performance it is strongly recommended that you compress the database when more than $object_limit loose objects exist.
 
@@ -2573,7 +2582,7 @@ Compress the database now?"] eq yes} {
                        do_gc
                }
        }
-       unset object_limit _junk objects_current
+       unset object_limit objects_current
 }
 
 lock_index begin-read