[PATCH 19/20] refs.c: make prune_ref use a transaction to delete the ref

[Ronnie Sahlberg <sahlberg@google.com>]

Change prune_ref to delete the ref using a ref transaction. To do this we also
need to add a new flag REF_ISPRUNING that will tell the transaction that we
do not want to delete this ref from the packed refs. This flag is private to
refs.c and not exposed to external callers.

Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c | 27 ++++++++++++++++++++-------
 refs.h | 14 ++++++++++++--
 2 files changed, 32 insertions(+), 9 deletions(-)

diff --git a/refs.c b/refs.c
index dbf6af9..186df37 100644
--- a/refs.c
+++ b/refs.c
@@ -25,6 +25,11 @@ static unsigned char refname_disposition[256] = {
 };
 
 /*
+ * Used as a flag to ref_transaction_delete when a loose ref is being
+ * pruned.
+ */
+#define REF_ISPRUNING	0x0100
+/*
  * Try to read one refname component from the front of refname.
  * Return the length of the component found, or -1 if the component is
  * not legal.  It is legal if it is something reasonable to have under
@@ -2379,17 +2384,24 @@ static void try_remove_empty_parents(char *name)
 /* make sure nobody touched the ref, and unlink */
 static void prune_ref(struct ref_to_prune *r)
 {
-	struct ref_lock *lock;
+	struct ref_transaction *transaction;
+	struct strbuf err = STRBUF_INIT;
 
 	if (check_refname_format(r->name + 5, 0))
 		return;
 
-	lock = lock_ref_sha1_basic(r->name, r->sha1, 0, NULL);
-	if (lock) {
-		unlink_or_warn(git_path("%s", r->name));
-		unlock_ref(lock);
-		try_remove_empty_parents(r->name);
+	transaction = ref_transaction_begin(&err);
+	if (!transaction ||
+	    ref_transaction_delete(transaction, r->name, r->sha1,
+				   REF_ISPRUNING, 1, &err) ||
+	    ref_transaction_commit(transaction, NULL, &err)) {
+		ref_transaction_free(transaction);
+		error("%s", err.buf);
+		strbuf_release(&err);
+		return;
 	}
+	ref_transaction_free(transaction);
+	try_remove_empty_parents(r->name);
 }
 
 static void prune_refs(struct ref_to_prune *r)
@@ -3598,8 +3610,9 @@ int ref_transaction_commit(struct ref_transaction *transaction,
 		struct ref_update *update = updates[i];
 
 		if (update->lock) {
-			delnames[delnum++] = update->lock->ref_name;
 			ret |= delete_ref_loose(update->lock, update->type);
+			if (!(update->flags & REF_ISPRUNING))
+				delnames[delnum++] = update->lock->ref_name;
 		}
 	}
 
diff --git a/refs.h b/refs.h
index 65dd593..aad846c 100644
--- a/refs.h
+++ b/refs.h
@@ -170,9 +170,19 @@ extern int ref_exists(const char *);
  */
 extern int peel_ref(const char *refname, unsigned char *sha1);
 
-/** Locks any ref (for 'HEAD' type refs). */
+/*
+ * Flags controlling lock_any_ref_for_update(), ref_transaction_update(),
+ * ref_transaction_create(), etc.
+ * REF_NODEREF: act on the ref directly, instead of dereferencing
+ *              symbolic references.
+ *
+ * Flags >= 0x100 are reserved for internal use.
+ */
 #define REF_NODEREF	0x01
-/* errno is set to something meaningful on failure */
+/*
+ * Locks any ref (for 'HEAD' type refs) and sets errno to something
+ * meaningful on failure.
+ */
 extern struct ref_lock *lock_any_ref_for_update(const char *refname,
 						const unsigned char *old_sha1,
 						int flags, int *type_p);
-- 
2.0.1.442.g7fe6834.dirty