[PATCH] filter-branch: add passed/remaining seconds on progress

["Gábor Bernát" <bernat@primeranks.net>]

From: Gabor Bernat <gabor.bernat@gravityrd.com>

adds seconds progress and estimated seconds time if getting the current
timestamp is supported by the date %+s command

Signed-off-by: Gabor Bernat <gabor.bernat@gravityrd.com>
---

I've submitted this first to this list as a feature request, however
in the meantime with the help of Jeff King <peff@peff.net>, Junio C
Hamano <gitster@pobox.com>, Eric Sunshine <sunshine@sunshineco.com>
and Mikael Magnusson <mikachu@gmail.com> came up with solution, so now
I submit it as a revised patch.

The current solution updates the progress for all commits until 1
second time is elapsed. Afterwards updates it at most once a second.
---
 git-filter-branch.sh | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 5b3f63d..5e9ae0f 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -277,9 +277,43 @@ test $commits -eq 0 && die "Found nothing to rewrite"
 # Rewrite the commits
 
 git_filter_branch__commit_count=0
+
+echo $(date +%s) | grep -q '^[0-9]+$';  2>/dev/null && show_seconds=t
+case "$show_seconds" in
+	t)
+		start_timestamp=$(date +%s)
+		next_sample_at=0
+		;;
+	'')
+		progress=""
+		;;
+esac
+
 while read commit parents; do
 	git_filter_branch__commit_count=$(($git_filter_branch__commit_count+1))
-	printf "\rRewrite $commit ($git_filter_branch__commit_count/$commits)"
+
+	case "$show_seconds" in
+	t)
+		if test $git_filter_branch__commit_count -gt $next_sample_at
+		then
+			now_timestamp=$(date +%s)
+			elapsed_seconds=$(($now_timestamp - $start_timestamp))
+			remaining_second=$(( ($commits - $git_filter_branch__commit_count) * $elapsed_seconds / $git_filter_branch__commit_count ))
+			if test $elapsed_seconds -gt 0
+			then
+				next_sample_at=$(( ($elapsed_seconds + 1) * $git_filter_branch__commit_count / $elapsed_seconds ))
+			else
+				next_sample_at=$(($next_sample_at + 1))
+			fi
+			progress=" ($elapsed_seconds seconds passed, remaining $remaining_second predicted)"
+		fi
+		;;
+	'')
+		progress=""
+		;;
+	esac
+
+	printf "\rRewrite $commit ($git_filter_branch__commit_count/$commits)$progress"
 
 	case "$filter_subdir" in
 	"")
-- 
2.5.1.408.g431338e