Fix max_transaction_time

lib/MySQL_Session.cpp

@@ -4691,12 +4691,6 @@ int MySQL_Session::handler() {
 	//unsigned int j;
 	//unsigned char c;
 
-	if (active_transactions == 0) {
-		active_transactions=NumActiveTransactions();
-		if (active_transactions > 0) {
-			transaction_started_at = thread->curtime;
-		}
-	}
 //	FIXME: Sessions without frontend are an ugly hack
 	if (session_fast_forward==false) {
 	if (client_myds==NULL) {
@@ -4968,6 +4962,14 @@ int MySQL_Session::handler() {
 				gtid_hid = -1;
 				if (rc==0) {
 
+					if (active_transactions != 0) {  // run this only if currently we think there is a transaction
+						if ((myconn->mysql->server_status & SERVER_STATUS_IN_TRANS) == 0) { // there is no transaction on the backend connection
+							active_transactions = NumActiveTransactions(); // we check all the hostgroups/backends
+							if (active_transactions == 0)
+								transaction_started_at = 0; // reset it
+						}
+					}
+
 					handler_rc0_Process_GTID(myconn);
 
 					// if we are locked on hostgroup, the value of autocommit is copied from the backend connection
@@ -5075,6 +5077,12 @@ int MySQL_Session::handler() {
 							handler_minus1_HandleBackendConnection(myds, myconn);
 						}
 					} else {
+						if (active_transactions == 0) {
+							active_transactions=NumActiveTransactions();
+							if (active_transactions > 0) {
+								transaction_started_at = thread->curtime;
+							}
+						}
 						switch (rc) {
 							// rc==1 , query is still running
 							// start sending to frontend if mysql_thread___threshold_resultset_size is reached
@@ -7206,8 +7214,7 @@ void MySQL_Session::MySQL_Result_to_MySQL_wire(MYSQL *mysql, MySQL_ResultSet *My
 		int myerrno=mysql_errno(mysql);
 		if (myerrno==0) {
 			unsigned int num_rows = mysql_affected_rows(mysql);
-			unsigned int nTrx=NumActiveTransactions();
-			uint16_t setStatus = (nTrx ? SERVER_STATUS_IN_TRANS : 0 );
+			uint16_t setStatus = (active_transactions ? SERVER_STATUS_IN_TRANS : 0);
 			if (autocommit) setStatus |= SERVER_STATUS_AUTOCOMMIT;
 			if (mysql->server_status & SERVER_MORE_RESULTS_EXIST)
 				setStatus |= SERVER_MORE_RESULTS_EXIST;

lib/MySQL_Thread.cpp

@@ -3746,18 +3746,6 @@ void MySQL_Thread::ProcessAllSessions_CompletedMirrorSession(unsigned int& n, My
 // this function was inline in MySQL_Thread::process_all_sessions()
 void MySQL_Thread::ProcessAllSessions_MaintenanceLoop(MySQL_Session *sess, unsigned long long sess_time, unsigned int& total_active_transactions_) {
 	unsigned int numTrx=0;
-	sess->active_transactions=sess->NumActiveTransactions();
-	{
-		sess->active_transactions=sess->NumActiveTransactions();
-		// in case we detected a new transaction just now
-		if (sess->active_transactions == 0) {
-			sess->transaction_started_at = 0;
-		} else {
-			if (sess->transaction_started_at == 0) {
-				sess->transaction_started_at = curtime;
-			}
-		}
-	}
 	total_active_transactions_ += sess->active_transactions;
 	sess->to_process=1;
 	if ( (sess_time/1000 > (unsigned long long)mysql_thread___max_transaction_idle_time) || (sess_time/1000 > (unsigned long long)mysql_thread___wait_timeout) ) {

test/tap/tests/test_max_transaction_time-t.cpp

@@ -0,0 +1,67 @@
+/**
+ * @file test_max_transaction_time-t.cpp
+ * @brief This test verifies that 'max_transaction_time' behaves properly.
+ *
+ * @details It verifies that connection with many transactions does not get
+ * killed by the max_transaction_time implementation if each individual
+ * transaction takes shorter than max_transaction_time.
+ */
+
+#include "mysql.h"
+
+#include "proxysql_utils.h"
+#include "tap.h"
+#include "utils.h"
+
+using std::string;
+
+int main(int, char**) {
+	CommandLine cl;
+
+	if (cl.getEnv()) {
+		diag("Failed to get the required environmental variables.");
+		return EXIT_FAILURE;
+	}
+
+	MYSQL* admin = mysql_init(NULL);
+	if (!mysql_real_connect(admin, cl.host, cl.admin_username, cl.admin_password, NULL, cl.admin_port, NULL, 0)) {
+		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(admin));
+		return EXIT_FAILURE;
+	}
+
+	diag("Configure the target server (non-existing) server to test connection failures");
+	MYSQL_QUERY_T(
+		admin,
+		"UPDATE global_variables SET variable_value = 10000 "
+		"WHERE variable_name = 'mysql-max_transaction_time'"
+	);
+	MYSQL_QUERY_T(admin, "LOAD MYSQL VARIABLES TO RUNTIME");
+
+	mysql_close(admin);
+
+	MYSQL* proxy = mysql_init(NULL);
+	if (!mysql_real_connect(proxy, cl.host, cl.username, cl.password, NULL, cl.port, NULL, 0)) {
+		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxy));
+		return EXIT_FAILURE;
+	}
+
+	diag("Run fifteen 1-second transactions:");
+	MYSQL_RES* myres;
+	for (int i = 0; i < 15; i++) {
+		MYSQL_QUERY_T(proxy, "BEGIN");
+
+		MYSQL_QUERY_T(proxy, "SELECT SLEEP(1)");
+		myres = mysql_store_result(proxy);
+		if (myres == nullptr) {
+			fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxy));
+			return EXIT_FAILURE;
+		}
+		mysql_free_result(myres);
+
+		MYSQL_QUERY_T(proxy, "COMMIT");
+	}
+
+	mysql_close(proxy);
+
+	return exit_status();
+}