Turn transaction_isolation into GUC enum

It was previously a string setting that was converted into an enum by
custom code, but using the GUC enum facility seems much simpler and
doesn't change any functionality, except that

    set transaction_isolation='default';

no longer works, but that was never documented and doesn't work with
any other transaction characteristics.  (Note that this is not the
same as RESET or SET TO DEFAULT, which still work.)

Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://www.postgresql.org/message-id/457db615-e84c-4838-310e-43841eb806e5@iki.fi

1 files changed, 2 insertions, 55 deletions

diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index 9a754dae3fd..c2d7a5bebf6 100644
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -522,32 +522,9 @@ check_transaction_read_only(bool *newval, void **extra, GucSource source)
  * As in check_transaction_read_only, allow it if not inside a transaction.
  */
 bool
-check_XactIsoLevel(char **newval, void **extra, GucSource source)
+check_XactIsoLevel(int *newval, void **extra, GucSource source)
 {
-	int			newXactIsoLevel;
-
-	if (strcmp(*newval, "serializable") == 0)
-	{
-		newXactIsoLevel = XACT_SERIALIZABLE;
-	}
-	else if (strcmp(*newval, "repeatable read") == 0)
-	{
-		newXactIsoLevel = XACT_REPEATABLE_READ;
-	}
-	else if (strcmp(*newval, "read committed") == 0)
-	{
-		newXactIsoLevel = XACT_READ_COMMITTED;
-	}
-	else if (strcmp(*newval, "read uncommitted") == 0)
-	{
-		newXactIsoLevel = XACT_READ_UNCOMMITTED;
-	}
-	else if (strcmp(*newval, "default") == 0)
-	{
-		newXactIsoLevel = DefaultXactIsoLevel;
-	}
-	else
-		return false;
+	int			newXactIsoLevel = *newval;
 
 	if (newXactIsoLevel != XactIsoLevel && IsTransactionState())
 	{
@@ -574,39 +551,9 @@ check_XactIsoLevel(char **newval, void **extra, GucSource source)
 		}
 	}
 
-	*extra = malloc(sizeof(int));
-	if (!*extra)
-		return false;
-	*((int *) *extra) = newXactIsoLevel;
-
 	return true;
 }
 
-void
-assign_XactIsoLevel(const char *newval, void *extra)
-{
-	XactIsoLevel = *((int *) extra);
-}
-
-const char *
-show_XactIsoLevel(void)
-{
-	/* We need this because we don't want to show "default". */
-	switch (XactIsoLevel)
-	{
-		case XACT_READ_UNCOMMITTED:
-			return "read uncommitted";
-		case XACT_READ_COMMITTED:
-			return "read committed";
-		case XACT_REPEATABLE_READ:
-			return "repeatable read";
-		case XACT_SERIALIZABLE:
-			return "serializable";
-		default:
-			return "bogus";
-	}
-}
-
 /*
  * SET TRANSACTION [NOT] DEFERRABLE
  */