Re: [PATCH 1/2] Clean up reflog unreachability pruning decision
From: Junio C Hamano <hidden>
Date: 2016-06-15 22:46:32
Linus Torvalds [off-list ref] writes:
From: Linus Torvalds <torvalds@linux-foundation.org> Date: Tue, 31 Mar 2009 09:45:22 -0700 This clarifies the pruning rules for unreachable commits by having a separate helpder function for the unreachability decision. It's preparation for actual bigger changes to come to speed up the decision when the reachability calculations become a bottleneck. In the process it also _does_ change behavior, although in a way that I think is much saner than the old behavior (which was in my opinion not designed, just a result of how the tests were written). It now will prune reflog entries that are older than that 'prune_unreacable' time _and_ that have commit references that can't be even looked up.
Of course, "--stale-fix" also does that, and does it regardless of the age of the reflog entry is, but I really think this is the right thing to do. If we can't even look it up, we should consider it to be unreachable. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- builtin-reflog.c | 32 ++++++++++++++++++++++++++------ 1 files changed, 26 insertions(+), 6 deletions(-) Note the behavioural change. I think it's sane and "ObviouslyCorrect(tm)", but maybe somebody disagrees.
I did not recall initially when I was discussing this with you last night
but I think this "no commit? not prune" is intentional. The codepath is
not about logs/heads but logs/*anything*, and we allow pointers to non
commit objects (like v2.6.11-tree).
Also even if we limit ourselves to commits, @{-N} notation can be used to
see the history of branch switching, and that does not need any underlying
objects. I do not think it is interesting to be able to see which branch
you were on 30 days abo, though ;-)
quoted hunk
diff --git a/builtin-reflog.c b/builtin-reflog.c index d95f515..0355ce6 100644 --- a/builtin-reflog.c +++ b/builtin-reflog.c@@ -209,6 +209,31 @@ static int keep_entry(struct commit **it, unsigned char *sha1) return 1; } +static int unreachable(struct expire_reflog_cb *cb, struct commit *commit, unsigned char *sha1) +{ + /* + * We may or may not have the commit yet - if not, look it + * up using the supplied sha1. + */ + if (!commit) { + if (is_null_sha1(sha1)) + return 0; + + commit = lookup_commit_reference_gently(sha1, 1); + + /* We can't even look it up - consider it unreachable */ + if (!commit) + return 1;
/* If it is not a commit, keep it. */
if (!commit)
return 0;
+ } + + /* Reachable from the current reflog top? Don't prune */
That's "tip of the ref", not necessarily "reflog top".
quoted hunk
+ if (in_merge_bases(commit, &cb->ref_commit, 1)) + return 0; + + /* We can't reach it - prune it. */ + return 1; +} + static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1, const char *email, unsigned long timestamp, int tz, const char *message, void *cb_data)@@ -230,12 +255,7 @@ static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1, if (timestamp < cb->cmd->expire_unreachable) { if (!cb->ref_commit) goto prune; - if (!old && !is_null_sha1(osha1)) - old = lookup_commit_reference_gently(osha1, 1); - if (!new && !is_null_sha1(nsha1)) - new = lookup_commit_reference_gently(nsha1, 1); - if ((old && !in_merge_bases(old, &cb->ref_commit, 1)) || - (new && !in_merge_bases(new, &cb->ref_commit, 1))) + if (unreachable(cb, old, osha1) || unreachable(cb, new, nsha1)) goto prune; }-- 1.6.2.1.404.gb0085.dirty