path: root/reflog-walk.h
diff options
authorJeff King <>2017-07-07 09:14:07 (GMT)
committerJunio C Hamano <>2017-07-09 17:00:48 (GMT)
commitd08565bf2dd78aa34c68c94f1931539c1c8c5322 (patch)
treee22019d02a8b81f7f6004284dcc654066effa1fc /reflog-walk.h
parent7f97de5ee1e1f9d28f45c8f7890e752f7b12bed1 (diff)
reflog-walk: stop using fake parents
The reflog-walk system works by putting a ref's tip into the pending queue, and then "traversing" the reflog by pretending that the parent of each commit is the previous reflog entry. This causes a number of user-visible oddities, as documented in t1414 (and the commit message which introduced it). We can fix all of them in one go by replacing the fake-reflog system with a much simpler one: just keeping a list of reflogs to show, and walking through them entry by entry. The implementation is fairly straight-forward, but there are a few items to note: 1. We obviously must skip calling add_parents_to_list() when we are traversing reflogs, since we do not want to walk the original parents at all. As a result, we must call try_to_simplify_commit() ourselves. There are other parts of add_parents_to_list() we skip, as well, but none of them should matter for a reflog traversal: - We do not allow UNINTERESTING commits, nor symmetric ranges (and we bail when these are used with "-g"). - Using --source makes no sense, since we aren't traversing. The reflog selector shows the same information with more detail. - Using --first-parent is still sensible, since you may want to see the first-parent diff for each entry. But since we're not traversing, we don't need to cull the parent list here. 2. Since we now just walk the reflog entries themselves, rather than starting with the ref tip, we now look at the "new" field of each entry rather than the "old" (i.e., we are showing entries, not faking parents). This removes all of the tricky logic around skipping past root commits. But note that we have no way to show an entry with the null sha1 in its "new" field (because such a commit obviously does not exist). Normally this would not happen, since we delete reflogs along with refs, but there is one special case. When we rename the currently checked out branch, we write two reflog entries into the HEAD log: one where the commit goes away, and another where it comes back. Prior to this commit, we show both entries with identical reflog messages. After this commit, we show only the "comes back" entry. See the update in t3200 which demonstrates this. Arguably either is fine, as the whole double-entry thing is a bit hacky in the first place. And until a recent fix, we truncated the traversal in such a case anyway, which was _definitely_ wrong. 3. We show individual reflogs in order, but choose which reflog to show at each stage based on which has the most recent timestamp. This interleaves the output from multiple reflogs based on date order, which is probably what you'd want with limiting like "-n 30". Note that the implementation aims for simplicity. It does a linear walk over the reflog queue for each commit it pulls, which may perform badly if you interleave an enormous number of reflogs. That seems like an unlikely use case; if we did want to handle it, we could probably keep a priority queue of reflogs, ordered by the timestamp of their current tip entry. Signed-off-by: Jeff King <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'reflog-walk.h')
1 files changed, 2 insertions, 2 deletions
diff --git a/reflog-walk.h b/reflog-walk.h
index af32361..373388c 100644
--- a/reflog-walk.h
+++ b/reflog-walk.h
@@ -8,8 +8,6 @@ struct reflog_walk_info;
extern void init_reflog_walk(struct reflog_walk_info **info);
extern int add_reflog_for_walk(struct reflog_walk_info *info,
struct commit *commit, const char *name);
-extern void fake_reflog_parent(struct reflog_walk_info *info,
- struct commit *commit);
extern void show_reflog_message(struct reflog_walk_info *info, int,
const struct date_mode *, int force_date);
extern void get_reflog_message(struct strbuf *sb,
@@ -22,4 +20,6 @@ extern void get_reflog_selector(struct strbuf *sb,
extern int reflog_walk_empty(struct reflog_walk_info *walk);
+struct commit *next_reflog_entry(struct reflog_walk_info *reflog_info);