public void run()

in naming/src/main/java/com/alibaba/nacos/naming/healthcheck/v2/processor/MysqlHealthCheckProcessor.java [127:205]
67 lines of code
17 McCabe index (conditional complexity)

        public void run() {
            
            Statement statement = null;
            ResultSet resultSet = null;
            
            try {
                String clusterName = instance.getCluster();
                String key =
                        service.getGroupedServiceName() + ":" + clusterName + ":" + instance.getIp() + ":" + instance
                                .getPort();
                Connection connection = CONNECTION_POOL.get(key);
                Mysql config = (Mysql) metadata.getHealthChecker();
                
                if (connection == null || connection.isClosed()) {
                    String url = "jdbc:mysql://" + instance.getIp() + ":" + instance.getPort() + "?connectTimeout="
                            + CONNECT_TIMEOUT_MS + "&socketTimeout=" + CONNECT_TIMEOUT_MS + "&loginTimeout=" + 1;
                    connection = DriverManager.getConnection(url, config.getUser(), config.getPwd());
                    CONNECTION_POOL.put(key, connection);
                }
                
                statement = connection.createStatement();
                statement.setQueryTimeout(1);
                
                resultSet = statement.executeQuery(config.getCmd());
                int resultColumnIndex = 2;
                
                if (CHECK_MYSQL_MASTER_SQL.equals(config.getCmd())) {
                    resultSet.next();
                    if (MYSQL_SLAVE_READONLY.equals(resultSet.getString(resultColumnIndex))) {
                        throw new IllegalStateException("current node is slave!");
                    }
                }
                
                healthCheckCommon.checkOk(task, service, "mysql:+ok");
                healthCheckCommon.reEvaluateCheckRt(System.currentTimeMillis() - startTime, task,
                        switchDomain.getMysqlHealthParams());
            } catch (SQLException e) {
                // fail immediately
                healthCheckCommon.checkFailNow(task, service, "mysql:" + e.getMessage());
                healthCheckCommon.reEvaluateCheckRt(switchDomain.getHttpHealthParams().getMax(), task,
                        switchDomain.getMysqlHealthParams());
            } catch (Throwable t) {
                Throwable cause = t;
                int maxStackDepth = 50;
                for (int deepth = 0; deepth < maxStackDepth && cause != null; deepth++) {
                    if (cause instanceof SocketTimeoutException || cause instanceof ConnectException
                            || cause instanceof TimeoutException || cause.getCause() instanceof TimeoutException) {
                        
                        healthCheckCommon.checkFail(task, service, "mysql:timeout:" + cause.getMessage());
                        healthCheckCommon.reEvaluateCheckRt(task.getCheckRtNormalized() * 2, task,
                                switchDomain.getMysqlHealthParams());
                        return;
                    }
                    
                    cause = cause.getCause();
                }
                
                // connection error, probably not reachable
                healthCheckCommon.checkFail(task, service, "mysql:error:" + t.getMessage());
                healthCheckCommon.reEvaluateCheckRt(switchDomain.getMysqlHealthParams().getMax(), task,
                        switchDomain.getMysqlHealthParams());
            } finally {
                instance.setCheckRt(System.currentTimeMillis() - startTime);
                if (statement != null) {
                    try {
                        statement.close();
                    } catch (SQLException e) {
                        Loggers.SRV_LOG.error("[MYSQL-CHECK] failed to close statement:" + statement, e);
                    }
                }
                if (resultSet != null) {
                    try {
                        resultSet.close();
                    } catch (SQLException e) {
                        Loggers.SRV_LOG.error("[MYSQL-CHECK] failed to close resultSet:" + resultSet, e);
                    }
                }
            }
        }