Fix Overflow in mysql_thread___threshold_resultset_size During Multiplication

include/gen_utils.h

@@ -314,6 +314,18 @@ inline unsigned long long realtime_time() {
   return (((unsigned long long) ts.tv_sec) * 1000000) + (ts.tv_nsec / 1000);
 }
 
+template<int FACTOR, typename T>
+inline T overflow_safe_multiply(T val) {
+	static_assert(std::is_integral<T>::value, "T must be an integer type.");
+	static_assert(std::is_unsigned_v<T>, "T must be an unsigned integer type.");
+	static_assert(FACTOR > 0, "Negative factors are not supported.");
+
+	if constexpr (FACTOR == 0) return 0;
+	if (val == 0)  return 0;
+	if (val > std::numeric_limits<T>::max() / FACTOR) return std::numeric_limits<T>::max();
+	return (val * FACTOR);
+}
+
 #endif /* __GEN_FUNCTIONS */
 
 bool Proxy_file_exists(const char *);

lib/MySQL_Thread.cpp

@@ -5995,7 +5995,7 @@ bool MySQL_Thread::set_backend_to_be_skipped_if_frontend_is_slow(MySQL_Data_Stre
 		// we pause receiving from backend at mysql_thread___threshold_resultset_size * 8
 		// but assuming that client isn't completely blocked, we will stop checking for data
 		// only at mysql_thread___threshold_resultset_size * 4
-		if (buffered_data > (unsigned int)mysql_thread___threshold_resultset_size*4) {
+		if (buffered_data > overflow_safe_multiply<4,unsigned int>(mysql_thread___threshold_resultset_size)) {
 			mypolls.fds[n].events = 0;
 			return true;
 		}

lib/mysql_connection.cpp

@@ -1509,7 +1509,7 @@ MDB_ASYNC_ST MySQL_Connection::handler(short event) {
 					unsigned int buffered_data=0;
 					buffered_data = myds->sess->client_myds->PSarrayOUT->len * RESULTSET_BUFLEN;
 					buffered_data += myds->sess->client_myds->resultset->len * RESULTSET_BUFLEN;
-					if (buffered_data > (unsigned int)mysql_thread___threshold_resultset_size*8) {
+					if (buffered_data > overflow_safe_multiply<8,unsigned int>(mysql_thread___threshold_resultset_size)) {
 						next_event(ASYNC_STMT_EXECUTE_STORE_RESULT_CONT); // we temporarily pause . See #1232
 						break;
 					}
@@ -1535,7 +1535,7 @@ MDB_ASYNC_ST MySQL_Connection::handler(short event) {
 					if (rows_read_inner > 1) {
 						process_rows_in_ASYNC_STMT_EXECUTE_STORE_RESULT_CONT(processed_bytes);
 						if (
-							(processed_bytes > (unsigned int)mysql_thread___threshold_resultset_size*8)
+							(processed_bytes > overflow_safe_multiply<8,unsigned int>(mysql_thread___threshold_resultset_size))
 								||
 							( mysql_thread___throttle_ratio_server_to_client && mysql_thread___throttle_max_bytes_per_second_to_client && (processed_bytes > (unsigned long long)mysql_thread___throttle_max_bytes_per_second_to_client/10*(unsigned long long)mysql_thread___throttle_ratio_server_to_client) )
 						) {
@@ -1688,7 +1688,7 @@ MDB_ASYNC_ST MySQL_Connection::handler(short event) {
 					unsigned int buffered_data=0;
 					buffered_data = myds->sess->client_myds->PSarrayOUT->len * RESULTSET_BUFLEN;
 					buffered_data += myds->sess->client_myds->resultset->len * RESULTSET_BUFLEN;
-					if (buffered_data > (unsigned int)mysql_thread___threshold_resultset_size*8) {
+					if (buffered_data > overflow_safe_multiply<8,unsigned int>(mysql_thread___threshold_resultset_size)) {
 						next_event(ASYNC_USE_RESULT_CONT); // we temporarily pause . See #1232
 						break;
 					}
@@ -1742,7 +1742,7 @@ MDB_ASYNC_ST MySQL_Connection::handler(short event) {
 					bytes_info.bytes_recv += br;
 					processed_bytes+=br;	// issue #527 : this variable will store the amount of bytes processed during this event
 					if (
-						(processed_bytes > (unsigned int)mysql_thread___threshold_resultset_size*8)
+						(processed_bytes > overflow_safe_multiply<8,unsigned int>(mysql_thread___threshold_resultset_size))
 							||
 						( mysql_thread___throttle_ratio_server_to_client && mysql_thread___throttle_max_bytes_per_second_to_client && (processed_bytes > (unsigned long long)mysql_thread___throttle_max_bytes_per_second_to_client/10*(unsigned long long)mysql_thread___throttle_ratio_server_to_client) )
 					) {

test/tap/tests/mysql-reg_test_4707_threshold_resultset_size-t.cpp

@@ -0,0 +1,113 @@
+ /**
+  * @file mysql-reg_test_4707_threshold_resultset_size-t.cpp
+  * @brief The test specifically examines the impact of different mysql-threshold_resultset_size threshold values on query response times
+  *     and addresses an identified issue caused by variable overflow, which results in slow performance.
+  */
+
+#include <string>
+#include <sstream>
+#include <chrono>
+#include "mysql.h"
+#include "command_line.h"
+#include "tap.h"
+#include "utils.h"
+
+CommandLine cl;
+
+int main(int argc, char** argv) {
+
+    plan(6); // Total number of tests planned
+
+    if (cl.getEnv())
+        return exit_status();
+
+    // Initialize Admin connection
+    MYSQL* proxysql_admin = mysql_init(NULL);
+    if (!proxysql_admin) {
+        fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxysql_admin));
+        return -1;
+    }
+
+    // Connnect to ProxySQL Admin
+    if (!mysql_real_connect(proxysql_admin, cl.admin_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(proxysql_admin));
+        return -1;
+    }
+
+    // Initialize Backend connection
+    MYSQL* proxysql_backend = mysql_init(NULL);
+    if (!proxysql_backend) {
+        fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxysql_backend));
+        return -1;
+    }
+
+    // Connnect to ProxySQL Backend
+    if (!mysql_real_connect(proxysql_backend, cl.host, cl.username, cl.password, NULL, cl.port, NULL, 0)) {
+        fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxysql_backend));
+        return -1;
+    }
+    MYSQL_QUERY(proxysql_admin, "DELETE FROM mysql_query_rules");
+    MYSQL_QUERY(proxysql_admin, "LOAD MYSQL QUERY RULES TO RUNTIME");
+    MYSQL_QUERY(proxysql_admin, "SET mysql-poll_timeout=2000");
+    MYSQL_QUERY(proxysql_admin, "SET mysql-threshold_resultset_size=8000");
+    MYSQL_QUERY(proxysql_admin, "LOAD MYSQL VARIABLES TO RUNTIME");
+
+    int rc;
+
+    auto start = std::chrono::high_resolution_clock::now();
+    rc = mysql_query(proxysql_backend, "SELECT 1");
+    auto end = std::chrono::high_resolution_clock::now();
+
+    if (rc == 0) {
+        MYSQL_RES* res = mysql_store_result(proxysql_backend);
+        ok(res != nullptr, "Query executed successfully. %s", mysql_error(proxysql_backend));
+        mysql_free_result(res);
+    }
+    else {
+        ok(false, "Error executing query. %s", mysql_error(proxysql_admin));
+    }
+
+    std::chrono::duration<double, std::milli> duration = end - start;
+    ok(duration.count() < 10.00, "Execution time should be less than 10 ms. Actual: %f ms", duration.count());
+
+    MYSQL_QUERY(proxysql_admin, "SET mysql-threshold_resultset_size=536870912");
+    MYSQL_QUERY(proxysql_admin, "LOAD MYSQL VARIABLES TO RUNTIME");
+
+    start = std::chrono::high_resolution_clock::now();
+    rc = mysql_query(proxysql_backend, "SELECT 1");
+    end = std::chrono::high_resolution_clock::now();
+
+    if (rc == 0) {
+        MYSQL_RES* res = mysql_store_result(proxysql_backend);
+        ok(res != nullptr, "Query executed successfully. %s", mysql_error(proxysql_backend));
+        mysql_free_result(res);
+    }
+    else {
+        ok(false, "Error executing query. %s", mysql_error(proxysql_admin));
+    }
+    duration = end - start;
+    ok(duration.count() < 10.00, "Execution time should be less than 10 ms. Actual: %f ms", duration.count());
+
+    MYSQL_QUERY(proxysql_admin, "SET mysql-threshold_resultset_size=1073741824");
+    MYSQL_QUERY(proxysql_admin, "LOAD MYSQL VARIABLES TO RUNTIME");
+
+    start = std::chrono::high_resolution_clock::now();
+    rc = mysql_query(proxysql_backend, "SELECT 1");
+    end = std::chrono::high_resolution_clock::now();
+
+    if (rc == 0) {
+        MYSQL_RES* res = mysql_store_result(proxysql_backend);
+        ok(res != nullptr, "Query executed successfully. %s", mysql_error(proxysql_backend));
+        mysql_free_result(res);
+    }
+    else {
+        ok(false, "Error executing query. %s", mysql_error(proxysql_admin));
+    }
+    duration = end - start;
+    ok(duration.count() < 10.00, "Execution time should be less than 10 ms. Actual: %f ms", duration.count());
+
+    mysql_close(proxysql_backend);
+    mysql_close(proxysql_admin);
+
+    return exit_status();
+}