# \[PATCH v6 15/42\] fast-import.c: change update\_branch to use ref transactions

- From: Ronnie Sahlberg \<hidden\>
- Date: 2016-06-15 23:00:58 
- List: git
- Page: https://ratatoskr.run/git/2016/06/7630775
- Thread: https://ratatoskr.run/git/2016/06/7630780/t.md

```text
Change update_branch() to use ref transactions for updates.

Signed-off-by: Ronnie Sahlberg <redacted>
---
 fast-import.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/fast-import.c b/fast-import.c
index 6707a66..79d219b 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1679,39 +1679,45 @@ found_entry:
 static int update_branch(struct branch *b)
 {
 	static const char *msg = "fast-import";
-	struct ref_lock *lock;
+	struct ref_transaction *transaction;
 	unsigned char old_sha1[20];
+	struct strbuf err = STRBUF_INIT;
 
 	if (read_ref(b->name, old_sha1))
 		hashclr(old_sha1);
+
 	if (is_null_sha1(b->sha1)) {
 		if (b->delete)
 			delete_ref(b->name, old_sha1, 0);
 		return 0;
 	}
-	lock = lock_any_ref_for_update(b->name, old_sha1, 0, NULL);
-	if (!lock)
-		return error("Unable to lock %s", b->name);
 	if (!force_update && !is_null_sha1(old_sha1)) {
 		struct commit *old_cmit, *new_cmit;
 
 		old_cmit = lookup_commit_reference_gently(old_sha1, 0);
 		new_cmit = lookup_commit_reference_gently(b->sha1, 0);
 		if (!old_cmit || !new_cmit) {
-			unlock_ref(lock);
 			return error("Branch %s is missing commits.", b->name);
 		}
 
 		if (!in_merge_bases(old_cmit, new_cmit)) {
-			unlock_ref(lock);
 			warning("Not updating %s"
 				" (new tip %s does not contain %s)",
 				b->name, sha1_to_hex(b->sha1), sha1_to_hex(old_sha1));
 			return -1;
 		}
 	}
-	if (write_ref_sha1(lock, b->sha1, msg) < 0)
-		return error("Unable to update %s", b->name);
+	transaction = ref_transaction_begin();
+	if ((!transaction ||
+	    ref_transaction_update(transaction, b->name, b->sha1, old_sha1,
+				   0, 1)) ||
+	    (ref_transaction_commit(transaction, msg, &err) &&
+	     !(transaction = NULL))) {
+		ref_transaction_rollback(transaction);
+		error("Unable to update branch %s: %s", b->name, err.buf);
+		strbuf_release(&err);
+		return -1;
+	}
 	return 0;
 }
 
-- 
2.0.0.rc1.351.g4d2c8e4
```