[PATCH v3 06/12] refs API: pass the "lock OID" to reflog "prepare"

[Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>]

Don't pass the object ID we pass into reflog_expire() back to the
caller, but rather our locked OID. As the assert shows these two were
the same thing in practice as we'd exit earlier in this function if we
couldn't lock the desired OID.

This is in preparation for a subsequent change of not having
reflog_expire() pass in the OID at all, also remove the "const" from
the parameter since the "struct ref_lock" does not have it on its
"old_oid" member.

As we'll see in a subsequent commit we don't actually want to assert
that we locked a given OID, we want this API to do the locking and
tell us what the OID is, but for now let's just setup the basic
scaffolding for that.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>
---
 builtin/reflog.c     | 4 ++--
 refs.h               | 4 ++--
 refs/debug.c         | 8 +++++---
 refs/files-backend.c | 3 ++-
 4 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/builtin/reflog.c b/builtin/reflog.c
index 09541d1c804..9f9e6bceb03 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -351,7 +351,7 @@ static int is_head(const char *refname)
 }
 
 static void reflog_expiry_prepare(const char *refname,
-				  const struct object_id *oid,
+				  struct object_id *locked_oid,
 				  void *cb_data)
 {
 	struct expire_reflog_policy_cb *cb = cb_data;
@@ -361,7 +361,7 @@ static void reflog_expiry_prepare(const char *refname,
 		cb->unreachable_expire_kind = UE_HEAD;
 	} else {
 		cb->tip_commit = lookup_commit_reference_gently(the_repository,
-								oid, 1);
+								locked_oid, 1);
 		if (!cb->tip_commit)
 			cb->unreachable_expire_kind = UE_ALWAYS;
 		else
diff --git a/refs.h b/refs.h
index 48970dfc7e0..c009707438d 100644
--- a/refs.h
+++ b/refs.h
@@ -796,7 +796,7 @@ enum expire_reflog_flags {
  * expiration policy that is desired.
  *
  * reflog_expiry_prepare_fn -- Called once after the reference is
- *     locked.
+ *     locked. Called with the OID of the locked reference.
  *
  * reflog_expiry_should_prune_fn -- Called once for each entry in the
  *     existing reflog. It should return true iff that entry should be
@@ -806,7 +806,7 @@ enum expire_reflog_flags {
  *     unlocked again.
  */
 typedef void reflog_expiry_prepare_fn(const char *refname,
-				      const struct object_id *oid,
+				      struct object_id *lock_oid,
 				      void *cb_data);
 typedef int reflog_expiry_should_prune_fn(struct object_id *ooid,
 					  struct object_id *noid,
diff --git a/refs/debug.c b/refs/debug.c
index 449ac3e6cc8..18fd9bca595 100644
--- a/refs/debug.c
+++ b/refs/debug.c
@@ -364,12 +364,14 @@ struct debug_reflog_expiry_should_prune {
 };
 
 static void debug_reflog_expiry_prepare(const char *refname,
-					const struct object_id *oid,
+					struct object_id *locked_oid,
 					void *cb_data)
 {
 	struct debug_reflog_expiry_should_prune *prune = cb_data;
-	trace_printf_key(&trace_refs, "reflog_expire_prepare: %s\n", refname);
-	prune->prepare(refname, oid, prune->cb_data);
+	trace_printf_key(&trace_refs, "reflog_expire_prepare: %s locket at %s\n",
+			 refname,
+			 oid_to_hex(locked_oid));
+	prune->prepare(refname, locked_oid, prune->cb_data);
 }
 
 static int debug_reflog_expiry_should_prune_fn(struct object_id *ooid,
diff --git a/refs/files-backend.c b/refs/files-backend.c
index af332fa8fe4..ce4b3fb1c7a 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -3098,7 +3098,8 @@ static int files_reflog_expire(struct ref_store *ref_store,
 		}
 	}
 
-	(*prepare_fn)(refname, oid, cb.policy_cb);
+	assert(oideq(&lock->old_oid, oid));
+	(*prepare_fn)(refname, &lock->old_oid, cb.policy_cb);
 	refs_for_each_reflog_ent(ref_store, refname, expire_reflog_ent, &cb);
 	(*cleanup_fn)(cb.policy_cb);
 
-- 
2.32.0.874.ge7a9d58bfcf