Re: [FEATURE REQUEST] Filter-branch extend progress with a simple estimated time remaning

From: Jeff King <peff@peff.net>
Date: Aug 25, 2015, 17:12 UTC
Message-ID: <20150825171238.GB9674@sigill.intra.peff.net>
In-Reply-To: <CANy2qHdngVjH_tPE6=Aao-A2JWrVb_wt2wdu4EzZDQwM6-t_=Q@mail.gmail.com>

On Tue, Aug 25, 2015 at 05:01:01PM +0200, Gabor Bernat wrote:

Show 10 quoted lines

> So it would be great if the filter-branch beside the Rewrite
> f8f0b351ae35ff7ac4bd58078cbba1aa34243779 (523/22625), would also
> append a basic ETA signaling the end of the operation.
> 
> It could be as simple as the the average number of milliseconds per
> step up to this point multiplied with the remaining number of steps,
> then convert this into a day:hour:minutes:seconds format. It sound
> simple enough, but really handy for long running filter branch
> operations. I could also contribute if one could direct me towards the
> appropriate files this should go to.

Yeah, I agree the current filter-branch progress reporting is pretty simplistic. The line you want to tweak is in git-filter-branch.sh:

  printf "\rRewrite $commit ($git_filter_branch__commit_count/$commits)"

But the real trick is getting accurate timing in a shell script. You can probably do the math within a "$(())" arithmetic block if you're OK with integers. But you'd have to run `date` on each loop iteration to get the current time, which may have a noticeable speed impact.

Of course, filter-branch is so slow in the first place, maybe it would not matter. :)

Something like this seems to work:

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 5b3f63d..04e45bc 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -276,10 +276,21 @@ test $commits -eq 0 && die "Found nothing to rewrite"
 
 # Rewrite the commits
 
+start=$(date +%s)
 git_filter_branch__commit_count=0
 while read commit parents; do
 	git_filter_branch__commit_count=$(($git_filter_branch__commit_count+1))
-	printf "\rRewrite $commit ($git_filter_branch__commit_count/$commits)"
+	now=$(date +%s)
+	elapsed=$(($now - $start))
+	# work in integer percentages as a sort of fixed-point
+	pct=$(($git_filter_branch__commit_count * 100 / $commits))
+	if test $pct -eq 0; then
+		remain=
+	else
+		eta=$(($elapsed * 100 / $pct))
+		remain="($(($eta - $elapsed)) seconds remaining)   "
+	fi
+	printf "\rRewrite $commit ($git_filter_branch__commit_count/$commits) $remain"
 
 	case "$filter_subdir" in
 	"")

but the time jumps around early on because of the lack of precision. And
of course there's no smoothing, and no emphasis on recent history versus
the whole operation. I'll leave those as an exercise to the reader. :)

-Peff