`QueryInfo::end_time` should always be greater than or equal to `start_time`

Signed-off-by: Wazir Ahmed <wazir@proxysql.com>

include/MySQL_Session.h

@@ -96,8 +96,33 @@ class Query_Info {
 	void end();
 	char *get_digest_text();
 	bool is_select_NOT_for_update();
+	void set_end_time(unsigned long long time);
 };
 
+/**
+ * @brief Assigns query end time.
+ * @details In addition to being a setter for end_time member variable, this
+ * method ensures that end_time is always greater than or equal to start_time.
+ * Refer https://github.com/sysown/proxysql/issues/4950 for more details.
+ * @param time query end time
+ */
+inline void Query_Info::set_end_time(unsigned long long time) {
+	end_time = time;
+
+#ifndef CLOCK_MONOTONIC_RAW
+	if (start_time <= end_time)
+		return;
+
+	// If start_time is greater than end_time, assign current monotonic time
+	end_time = monotonic_time();
+	if (start_time <= end_time)
+		return;
+
+	// If start_time is still greater than end_time, set the difference to 0
+	end_time = start_time;
+#endif // CLOCK_MONOTONIC_RAW
+}
+
 /**
  * @class MySQL_Session
  * @brief Manages a client session, including query parsing, backend connections, and state transitions.

include/PgSQL_Session.h

@@ -179,12 +179,37 @@ public:
 	void end();
 	char* get_digest_text();
 	bool is_select_NOT_for_update();
+	void set_end_time(unsigned long long time);
 
 private:
 	void reset_extended_query_info();
 	void init(unsigned char* _p, int len, bool header = false);
 };
 
+/**
+ * @brief Assigns query end time.
+ * @details In addition to being a setter for end_time member variable, this
+ * method ensures that end_time is always greater than or equal to start_time.
+ * Refer https://github.com/sysown/proxysql/issues/4950 for more details.
+ * @param time query end time
+ */
+inline void PgSQL_Query_Info::set_end_time(unsigned long long time) {
+	end_time = time;
+
+#ifndef CLOCK_MONOTONIC_RAW
+	if (start_time <= end_time)
+		return;
+
+	// If start_time is greater than end_time, assign current monotonic time
+	end_time = monotonic_time();
+	if (start_time <= end_time)
+		return;
+
+	// If start_time is still greater than end_time, set the difference to 0
+	end_time = start_time;
+#endif // CLOCK_MONOTONIC_RAW
+}
+
 class PgSQL_Session : public Base_Session<PgSQL_Session, PgSQL_Data_Stream, PgSQL_Backend, PgSQL_Thread> {
 private:
 	using PktType = std::variant<std::unique_ptr<PgSQL_Parse_Message>,std::unique_ptr<PgSQL_Describe_Message>,

lib/MySQL_Session.cpp

@@ -3322,7 +3322,7 @@ void MySQL_Session::handler___status_WAITING_CLIENT_DATA___STATE_SLEEP___MYSQL_C
 			l_free(pkt.size,pkt.ptr);
 			client_myds->DSS=STATE_SLEEP;
 			status=WAITING_CLIENT_DATA;
-			CurrentQuery.end_time=thread->curtime;
+			CurrentQuery.set_end_time(thread->curtime);
 			CurrentQuery.end();
 		} else {
 			mybe=find_or_create_backend(current_hostgroup);
@@ -7527,7 +7527,7 @@ unsigned long long MySQL_Session::IdleTime() {
 void MySQL_Session::LogQuery(MySQL_Data_Stream *myds, const unsigned int myerrno, const char * errmsg) {
 	// we need to access statistics before calling CurrentQuery.end()
 	// so we track the time here
-	CurrentQuery.end_time=thread->curtime;
+	CurrentQuery.set_end_time(thread->curtime);
 
 	if (qpo) {
 		if (qpo->log==1) {

lib/PgSQL_Session.cpp

@@ -4885,7 +4885,7 @@ unsigned long long PgSQL_Session::IdleTime() {
 void PgSQL_Session::LogQuery(PgSQL_Data_Stream* myds) {
 	// we need to access statistics before calling CurrentQuery.end()
 	// so we track the time here
-	CurrentQuery.end_time = thread->curtime;
+	CurrentQuery.set_end_time(thread->curtime);
 
 	if (qpo) {
 		if (qpo->log == 1) {