Do not kill Session if a backend failed

This new algorithm makes the backend connection fails instead of killing the session
This is an improvement over issue #1085

include/MySQL_Session.h

@@ -216,6 +216,7 @@ class MySQL_Session
 	void MySQL_Stmt_Result_to_MySQL_wire(MYSQL_STMT *stmt, MySQL_Connection *myconn);
 	unsigned int NumActiveTransactions();
 	bool HasOfflineBackends();
+	bool SetEventInOfflineBackends();
 	int FindOneActiveTransaction();
 	unsigned long long IdleTime();
 

lib/MySQL_Session.cpp

@@ -4902,6 +4902,23 @@ bool MySQL_Session::HasOfflineBackends() {
 	return ret;
 }
 
+bool MySQL_Session::SetEventInOfflineBackends() {
+	bool ret=false;
+	if (mybes==0) return ret;
+	MySQL_Backend *_mybe;
+	unsigned int i;
+	for (i=0; i < mybes->len; i++) {
+		_mybe=(MySQL_Backend *)mybes->index(i);
+		if (_mybe->server_myds)
+			if (_mybe->server_myds->myconn)
+				if (_mybe->server_myds->myconn->IsServerOffline()) {
+					_mybe->server_myds->revents|=POLLIN;
+					ret = true;
+				}
+	}
+	return ret;
+}
+
 int MySQL_Session::FindOneActiveTransaction() {
 	int ret=-1;
 	if (mybes==0) return ret;

lib/MySQL_Thread.cpp

@@ -3579,8 +3579,14 @@ void MySQL_Thread::process_all_sessions() {
 				}
 				if (servers_table_version_current != servers_table_version_previous) { // bug fix for #1085
 					// Immediatelly kill all client connections using an OFFLINE node
-					if (sess->HasOfflineBackends()) {
-						sess->killed=true;
+					//if (sess->HasOfflineBackends()) {
+					//	sess->killed=true;
+					//}
+					// Search for connections that should be terminated, and simulate data in them
+					// the following 2 lines of code replace the previous 2 lines
+					// instead of killing the sessions, fails the backend connections
+					if (sess->SetEventInOfflineBackends()) {
+						sess->to_process=1;
 					}
 				}
 			}