From a3316077c724a1d1e08903759f7c24bd9807edc0 Mon Sep 17 00:00:00 2001
From: Rahim Kanji <rahim.kanji@outlook.com>
Date: Wed, 1 Mar 2023 15:29:47 +0500
Subject: [PATCH] Unregistering connection from connection pool as soon as
 failure is detected to minimize race condition. (This only impacts debug
 build)

---
 lib/MySQL_Monitor.cpp | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/lib/MySQL_Monitor.cpp b/lib/MySQL_Monitor.cpp
index f258a6fe7..cb7b6f575 100644
--- a/lib/MySQL_Monitor.cpp
+++ b/lib/MySQL_Monitor.cpp
@@ -6763,6 +6763,10 @@ public:
 			for (unsigned int i = 0; i < len_;) {
 
 				if (mmsds_[i]->task_handler(fds_[i].revents, fds_[i].events) != MySQL_Monitor_State_Data_Task_Result::TASK_RESULT_PENDING) {
+#ifdef DEBUG
+					if (mmsds_[i]->get_task_result() != MySQL_Monitor_State_Data_Task_Result::TASK_RESULT_SUCCESS)
+						GloMyMon->My_Conn_Pool->conn_unregister(mmsds_[i]);
+#endif // DEBUG
 					ready_tasks.push_back(mmsds_[i]);
 					remove_index_fast(i);
 
@@ -6924,9 +6928,9 @@ bool MySQL_Monitor::monitor_ping_process_ready_tasks(const std::vector<MySQL_Mon
 				proxy_error("Error after %lldms on server %s:%d : %s\n", (mmsd->t2 - mmsd->t1) / 1000, mmsd->hostname, mmsd->port, (mmsd->mysql_error_msg ? mmsd->mysql_error_msg : ""));
 #endif // DEBUG
 			}
-#ifdef DEBUG
-			My_Conn_Pool->conn_unregister(mmsd);
-#endif // DEBUG
+//#ifdef DEBUG
+//			My_Conn_Pool->conn_unregister(mmsd);
+//#endif // DEBUG
 			mysql_close(mmsd->mysql);
 			mmsd->mysql = NULL;
 		}
@@ -7112,9 +7116,9 @@ bool MySQL_Monitor::monitor_read_only_process_ready_tasks(const std::vector<MySQ
 				proxy_error("Got error: mmsd %p , MYSQL %p , FD %d : %s\n", mmsd, mmsd->mysql, mmsd->mysql->net.fd, (mmsd->mysql_error_msg ? mmsd->mysql_error_msg : ""));
 #endif
 			}
-#ifdef DEBUG
-			My_Conn_Pool->conn_unregister(mmsd);
-#endif // DEBUG
+//#ifdef DEBUG
+//			My_Conn_Pool->conn_unregister(mmsd);
+//#endif // DEBUG
 			mysql_close(mmsd->mysql);
 			mmsd->mysql = NULL;
 		}
@@ -7290,9 +7294,9 @@ bool MySQL_Monitor::monitor_group_replication_process_ready_tasks(const std::vec
 				proxy_error("Got error: mmsd %p , MYSQL %p , FD %d : %s\n", mmsd, mmsd->mysql, mmsd->mysql->net.fd, (mmsd->mysql_error_msg ? mmsd->mysql_error_msg : ""));
 #endif
 			}
-#ifdef DEBUG
-			My_Conn_Pool->conn_unregister(mmsd);
-#endif // DEBUG
+//#ifdef DEBUG
+//			My_Conn_Pool->conn_unregister(mmsd);
+//#endif // DEBUG
 			mysql_close(mmsd->mysql);
 			mmsd->mysql = NULL;
 		}
@@ -7532,9 +7536,9 @@ bool MySQL_Monitor::monitor_replication_lag_process_ready_tasks(const std::vecto
 				proxy_error("Error after %lldms on server %s:%d : %s\n", (mmsd->t2 - mmsd->t1) / 1000, mmsd->hostname, mmsd->port, (mmsd->mysql_error_msg ? mmsd->mysql_error_msg : ""));
 #endif
 			}
-#ifdef DEBUG
-			My_Conn_Pool->conn_unregister(mmsd);
-#endif
+//#ifdef DEBUG
+//			My_Conn_Pool->conn_unregister(mmsd);
+//#endif
 			mysql_close(mmsd->mysql);
 			mmsd->mysql = NULL;
 		}
@@ -7691,9 +7695,9 @@ bool MySQL_Monitor::monitor_galera_process_ready_tasks(const std::vector<MySQL_M
 				proxy_error("Got error: mmsd %p , MYSQL %p , FD %d : %s\n", mmsd, mmsd->mysql, mmsd->mysql->net.fd, (mmsd->mysql_error_msg ? mmsd->mysql_error_msg : ""));
 #endif
 			}
-#ifdef DEBUG
-			My_Conn_Pool->conn_unregister(mmsd);
-#endif // DEBUG
+//#ifdef DEBUG
+//			My_Conn_Pool->conn_unregister(mmsd);
+//#endif // DEBUG
 			mysql_close(mmsd->mysql);
 			mmsd->mysql = NULL;
 		}