refs/files: remove duplicate duplicates check

Within the files reference backend's transaction's 'finish' phase, a
verification step is currently performed wherein the refnames list is
sorted and examined for multiple updates targeting the same refname.

It has been observed that this verification is redundant, as an
identical check is already executed during the transaction's 'prepare'
stage. Since the refnames list remains unmodified following the
'prepare' stage, this secondary verification can be safely eliminated.

The duplicate check has been removed accordingly, and the
`ref_update_reject_duplicates()` function has been marked as static, as
its usage is now confined to 'refs.c'.

Signed-off-by: Karthik Nayak <[email protected]>
Acked-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: KarthikNayak

refs.c

@@ -2303,8 +2303,13 @@ int refs_update_symref_extended(struct ref_store *refs, const char *ref,
 	return ret;
 }
 
-int ref_update_reject_duplicates(struct string_list *refnames,
-				 struct strbuf *err)
+/*
+ * Write an error to `err` and return a nonzero value iff the same
+ * refname appears multiple times in `refnames`. `refnames` must be
+ * sorted on entry to this function.
+ */
+static int ref_update_reject_duplicates(struct string_list *refnames,
+					struct strbuf *err)
 {
 	size_t i, n = refnames->nr;
 

refs/files-backend.c

@@ -3016,12 +3016,6 @@ static int files_transaction_finish_initial(struct files_ref_store *refs,
 	if (transaction->state != REF_TRANSACTION_PREPARED)
 		BUG("commit called for transaction that is not prepared");
 
-	string_list_sort(&transaction->refnames);
-	if (ref_update_reject_duplicates(&transaction->refnames, err)) {
-		ret = TRANSACTION_GENERIC_ERROR;
-		goto cleanup;
-	}
-
 	/*
 	 * It's really undefined to call this function in an active
 	 * repository or when there are existing references: we are

refs/refs-internal.h

@@ -142,14 +142,6 @@ int refs_read_raw_ref(struct ref_store *ref_store, const char *refname,
 		      struct object_id *oid, struct strbuf *referent,
 		      unsigned int *type, int *failure_errno);
 
-/*
- * Write an error to `err` and return a nonzero value iff the same
- * refname appears multiple times in `refnames`. `refnames` must be
- * sorted on entry to this function.
- */
-int ref_update_reject_duplicates(struct string_list *refnames,
-				 struct strbuf *err);
-
 /*
  * Add a ref_update with the specified properties to transaction, and
  * return a pointer to the new object. This function does not verify