rev-list: add optional progress reporting

It's easy to ask rev-list to do a traversal that may takes
many seconds (e.g., by calling "--objects --all"). In theory
you can monitor its progress by the output you get to
stdout, but this isn't always easy.

Some operations, like "--count", don't make any output until
the end.

And some callers, like check_everything_connected(), are
using it just for the error-checking of the traversal, and
throw away stdout entirely.

This patch adds a "--progress" option which can be used to
give some eye-candy for a user waiting for a long traversal.
This is just a rev-list option and not a regular traversal
option, because it needs cooperation from the callbacks in
builtin/rev-list.c to do the actual count.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index c5bd21812d..f39cb6d4f5 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -274,6 +274,10 @@ ifdef::git-rev-list[]
 	Try to speed up the traversal using the pack bitmap index (if
 	one is available). Note that when traversing with `--objects`,
 	trees and blobs will not have their associated path printed.
+
+--progress=<header>::
+	Show progress reports on stderr as objects are considered. The
+	`<header>` text will be printed with each progress update.
 endif::git-rev-list[]
 
 --