[PATCH v6 41/42] refs.c: make rename_ref use a transaction

[Ronnie Sahlberg <sahlberg@google.com>]

Change rename_ref to use a single transaction to perform the ref rename.

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
---
 refs.c | 73 ++++++++++++++++++------------------------------------------------
 1 file changed, 20 insertions(+), 53 deletions(-)

diff --git a/refs.c b/refs.c
index eb75927..810a4db 100644
--- a/refs.c
+++ b/refs.c
@@ -2586,9 +2586,10 @@ static int rename_tmp_log(const char *newrefname)
 
 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
 {
-	unsigned char sha1[20], orig_sha1[20];
-	int flag = 0, logmoved = 0;
-	struct ref_lock *lock;
+	unsigned char sha1[20];
+	int flag = 0;
+	struct ref_transaction *transaction;
+	struct strbuf err = STRBUF_INIT;
 	struct stat loginfo;
 	int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
 	const char *symref = NULL;
@@ -2599,7 +2600,7 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
 	if (log && S_ISLNK(loginfo.st_mode))
 		return error("reflog for %s is a symlink", oldrefname);
 
-	symref = resolve_ref_unsafe(oldrefname, orig_sha1, 1, &flag);
+	symref = resolve_ref_unsafe(oldrefname, sha1, 1, &flag);
 	if (flag & REF_ISSYMREF)
 		return error("refname %s is a symbolic ref, renaming it is not supported",
 			oldrefname);
@@ -2621,62 +2622,28 @@ int rename_ref(const char *oldrefname, const char *newrefname, const char *logms
 	if (pack_refs(PACK_REFS_ALL | PACK_REFS_PRUNE))
 		return error("unable to pack refs");
 
-	if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
-		error("unable to delete old %s", oldrefname);
-		goto rollback;
-	}
-
-	if (!read_ref_full(newrefname, sha1, 1, NULL) &&
-	    delete_ref(newrefname, sha1, REF_NODEREF)) {
-		if (errno==EISDIR) {
-			if (remove_empty_directories(git_path("%s", newrefname))) {
-				error("Directory not empty: %s", newrefname);
-				goto rollback;
-			}
-		} else {
-			error("unable to delete existing %s", newrefname);
-			goto rollback;
-		}
+	transaction = ref_transaction_begin();
+	if (!transaction ||
+	    ref_transaction_delete(transaction, oldrefname, sha1,
+				   REF_NODEREF | REF_ISPACKONLY,
+				   1, NULL) ||
+	    ref_transaction_update(transaction, newrefname, sha1,
+				   NULL, 0, 0, logmsg) ||
+	    ref_transaction_commit(transaction, &err)) {
+		ref_transaction_rollback(transaction);
+		error("rename_ref failed: %s", err.buf);
+		strbuf_release(&err);
+		goto rollbacklog;
 	}
+	ref_transaction_free(transaction);
 
 	if (log && rename_tmp_log(newrefname))
-		goto rollback;
-
-	logmoved = log;
-
-	lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL, NULL, 0);
-	if (!lock) {
-		error("unable to lock %s for update", newrefname);
-		goto rollback;
-	}
-	lock->force_write = 1;
-	hashcpy(lock->old_sha1, orig_sha1);
-	if (write_ref_sha1(lock, orig_sha1, logmsg)) {
-		error("unable to write current sha1 into %s", newrefname);
-		goto rollback;
-	}
-
-	return 0;
-
- rollback:
-	lock = lock_ref_sha1_basic(oldrefname, NULL, 0, NULL, NULL, 0);
-	if (!lock) {
-		error("unable to lock %s for rollback", oldrefname);
 		goto rollbacklog;
-	}
 
-	lock->force_write = 1;
-	flag = log_all_ref_updates;
-	log_all_ref_updates = 0;
-	if (write_ref_sha1(lock, orig_sha1, NULL))
-		error("unable to write current sha1 into %s", oldrefname);
-	log_all_ref_updates = flag;
+	return 0;
 
  rollbacklog:
-	if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
-		error("unable to restore logfile %s from %s: %s",
-			oldrefname, newrefname, strerror(errno));
-	if (!logmoved && log &&
+	if (log &&
 	    rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
 		error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
 			oldrefname, strerror(errno));
-- 
2.0.0.rc1.351.g4d2c8e4