[PATCH v4 06/10] commit-graph write: show progress for object search

[Ævar Arnfjörð Bjarmason]

Show the percentage progress for the "Finding commits for commit
graph" phase for the common case where we're operating on all packs in
the repository, as "commit-graph write" or "gc" will do.

Before we'd emit on e.g. linux.git with "commit-graph write":

    Finding commits for commit graph: 6365442, done.
    [...]

And now:

    Finding commits for commit graph: 100% (6365442/6365442), done.
    [...]

Since the commit graph only includes those commits that are packed
(via for_each_packed_object(...)) the approximate_object_count()
returns the actual number of objects we're going to process.

Still, it is possible due to a race with "gc" or another process
maintaining packs that the number of objects we're going to process is
lower than what approximate_object_count() reported. In that case we
don't want to stop the progress bar short of 100%. So let's make sure
it snaps to 100% at the end.

The inverse case is also possible and more likely. I.e. that a new
pack has been added between approximate_object_count() and
for_each_packed_object(). In that case the percentage will go beyond
100%, and we'll do nothing to snap it back to 100% at the end.

Signed-off-by: Ævar Arnfjörð Bjarmason <ava...@gmail.com>
---
 commit-graph.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/commit-graph.c b/commit-graph.c
index 3de65bc2e9..42d8365f0d 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -781,12 +781,14 @@ void write_commit_graph(const char *obj_dir,
        struct progress *progress = NULL;
        uint64_t progress_cnt = 0;
        struct strbuf progress_title = STRBUF_INIT;
+       unsigned long approx_nr_objects;
 
        if (!commit_graph_compatible(the_repository))
                return;
 
        oids.nr = 0;
-       oids.alloc = approximate_object_count() / 32;
+       approx_nr_objects = approximate_object_count();
+       oids.alloc = approx_nr_objects / 32;
        oids.progress = NULL;
        oids.progress_done = 0;
 
@@ -866,8 +868,11 @@ void write_commit_graph(const char *obj_dir,
        if (!pack_indexes && !commit_hex) {
                if (report_progress)
                        oids.progress = start_delayed_progress(
-                               _("Finding commits for commit graph"), 0);
+                               _("Finding commits for commit graph"),
+                               approx_nr_objects);
                for_each_packed_object(add_packed_commits, &oids, 0);
+               if (oids.progress_done < approx_nr_objects)
+                       display_progress(oids.progress, approx_nr_objects);
                stop_progress(&oids.progress);
        }
 
-- 
2.20.0.rc0.387.gc7a69e6b6c