[#21438] YSQL: Forward errors around drop db/role as accurately as po…

…ssible

Summary:
This diff changes the error forwarding in place when dealing with errors around database/user being dropped with Connection Manager.

Old behaviour:
- We would earlier construct an error message from the message/hint of the server's error (depending on invalid user or database, respectively) and forward to client, along with a hardcoded SQLState.
- In a scenario with multiple logical connections in a dropped/invalid pool we would use the information that if the current db/user is dropped, then construct an error from Connection Manager to be forwarded to the client, rather than relying on the error sent by the server

New behaviour:
- Forward the server error, including its detail and hint, if any, as it is, back to the client
- Despite of knowing that the currently used db/user is dropped, still forward the client query to the server, then forward this error transparently back to the user as in the previous point

Jira: DB-10320

Test Plan: Jenkins: enable connection manager, all tests

Reviewers: skumar, devansh.saxena, mkumar, stiwary, vpatibandla

Reviewed By: devansh.saxena

Subscribers: yql

Differential Revision: https://phorge.dev.yugabyte.com/D41398

src/odyssey/sources/backend.c

@@ -72,6 +72,8 @@ void od_backend_error(od_server_t *server, char *context, char *data,
 {
 	od_instance_t *instance = server->global->instance;
 	kiwi_fe_error_t error;
+	int detail_len = 0;
+	int hint_len = 0;
 
 	od_client_t *yb_server_client = server->client;
 	od_client_t *yb_external_client = (yb_server_client->yb_is_authenticating) ?
@@ -92,6 +94,7 @@ void od_backend_error(od_server_t *server, char *context, char *data,
 	if (error.detail) {
 		od_error(&instance->logger, context, yb_external_client, server,
 			 "DETAIL: %s", error.detail);
+		detail_len = strlen(error.detail);
 	}
 
 	/* catch and store error to be forwarded later if we are in deploy phase */
@@ -104,6 +107,7 @@ void od_backend_error(od_server_t *server, char *context, char *data,
 	if (error.hint) {
 		od_error(&instance->logger, context, yb_external_client, server,
 			 "HINT: %s", error.hint);
+		hint_len = strlen(error.hint);
 
 		if (strcmp(error.hint, "Database might have been dropped by another user") == 0)
 		{
@@ -113,10 +117,16 @@ void od_backend_error(od_server_t *server, char *context, char *data,
 			if (yb_external_client != NULL &&
 			    ((od_client_t *)yb_external_client)->type ==
 				    OD_POOL_CLIENT_EXTERNAL)
-				od_frontend_error(
-					yb_external_client,
-					KIWI_CONNECTION_DOES_NOT_EXIST,
-					error.hint, od_io_error(&server->io));
+			{
+				machine_msg_t *msg;
+				msg = kiwi_be_write_error_as(NULL, error.severity, error.code,
+				     error.detail, detail_len, error.hint,
+				     hint_len, error.message, strlen(error.message));
+				/* YB: best-effort forward to client, already handling error */
+				if (msg == NULL)
+					return;
+				od_write(&yb_external_client->io, msg);
+			}
 		}
 	}
 
@@ -126,8 +136,17 @@ void od_backend_error(od_server_t *server, char *context, char *data,
 
 		if (yb_external_client != NULL &&
 			((od_client_t *)yb_external_client)->type == OD_POOL_CLIENT_EXTERNAL)
-				od_frontend_error(yb_external_client, KIWI_CONNECTION_DOES_NOT_EXIST, error.message);
-	}
+			{
+				machine_msg_t *msg;
+				msg = kiwi_be_write_error_as(NULL, error.severity, error.code,
+				     error.detail, detail_len, error.hint,
+				     hint_len, error.message, strlen(error.message));
+				/* YB: best-effort forward to client, already handling error */
+				if (msg == NULL)
+					return;
+				od_write(&yb_external_client->io, msg);
+			}	
+		}
 }
 
 int od_backend_ready(od_server_t *server, char *data, uint32_t size)

src/odyssey/sources/frontend.c

@@ -322,6 +322,7 @@ od_frontend_attach(od_client_t *client, char *context,
 				continue;
 			}
 
+			/* YB: check auth failure status codes to update OID status */
 			if (yb_frontend_error_is_db_does_not_exist(client))
 				((od_route_t *)server->route)->yb_database_entry->status = YB_OID_DROPPED;
 			else if (yb_frontend_error_is_role_does_not_exist(client))
@@ -1977,22 +1978,6 @@ static od_frontend_status_t od_frontend_remote(od_client_t *client)
 
 	for (;;) {
 		for (;;) {
-			rc = yb_is_route_invalid(client->route);
-			if (rc == ROUTE_INVALID_DB_OID) {
-				od_frontend_fatal(
-					client, KIWI_CONNECTION_FAILURE,
-					"Database might have been dropped by another user");
-				status = OD_ECLIENT_READ;
-				break;
-			} else if (rc == ROUTE_INVALID_ROLE_OID) {
-				od_frontend_fatal(
-					client, KIWI_CONNECTION_FAILURE,
-					"invalid role OID: %d",
-					((od_route_t *)(client->route))->yb_user_entry->oid);
-				status = OD_ECLIENT_READ;
-				break;
-			}
-
 			if (od_should_drop_connection(client, server)) {
 				/* Odyssey is going to shut down or client conn is dropped
 				* due some idle timeout, we drop the connection  */