Refactor connector code

app/app.go

@@ -84,7 +84,11 @@ func NewApp(
 	app := new(App)
 
 	anonymiser.Enable(settings.Anonymise)
-	app.db = connector.NewConnector(connectorFlags).DB
+	conn, err := connector.NewConnector(connectorFlags)
+	if err != nil {
+		return nil, fmt.Errorf("failed to connect to database: %w", err)
+	}
+	app.db = conn.DB
 
 	status := global.NewStatus(app.db)
 	variables := global.NewVariables(app.db)
@@ -124,10 +128,10 @@ func NewApp(
 
 	app.resetDBStatistics()
 
-	var err error
-	app.currentView, err = view.SetupAndValidate(settings.ViewName, app.db) // if empty will use the default
-	if err != nil {
-		return nil, fmt.Errorf("app.NewApp: %w", err)
+	var viewErr error
+	app.currentView, viewErr = view.SetupAndValidate(settings.ViewName, app.db) // if empty will use the default
+	if viewErr != nil {
+		return nil, fmt.Errorf("app.NewApp: %w", viewErr)
 	}
 	app.UpdateCurrentTabler()
 

connector/connector.go

@@ -6,11 +6,9 @@ import (
 	"database/sql"
 	"fmt"
 	"math"
-	"os"
 
 	"github.com/sjmudd/mysql_defaults_file"
 	"github.com/sjmudd/ps-top/log"
-	"github.com/sjmudd/ps-top/utils"
 )
 
 // Method indicates how we want to connect to MySQL
@@ -101,51 +99,24 @@ func (c *Connector) Connect() error {
 	return nil
 }
 
-// ConnectByConfig connects to MySQL using various configuration settings
-// needed to create the DSN.
-func (c *Connector) ConnectByConfig(config mysql_defaults_file.Config) {
-	c.config = config
-	c.SetMethod(ConnectByConfig)
-	if err := c.Connect(); err != nil {
-		fmt.Println(utils.ProgName+": ConnectByConfig failed:", err.Error())
-		os.Exit(1)
-	}
-}
-
-// ConnectByDefaultsFile connects to the database with the given
-// defaults-file, or ~/.my.cnf if not provided.
-func (c *Connector) ConnectByDefaultsFile(defaultsFile string) {
-	c.config = mysql_defaults_file.NewConfig(defaultsFile)
-	c.SetMethod(ConnectByDefaultsFile)
-	if err := c.Connect(); err != nil {
-		fmt.Println(utils.ProgName+": ConnectByDefaultsFile failed:", err.Error())
-		os.Exit(1)
-	}
-}
 
-// ConnectByEnvironment connects using environment variables
-func (c *Connector) ConnectByEnvironment() {
-	c.SetMethod(ConnectByEnvironment)
-	if err := c.Connect(); err != nil {
-		fmt.Println(utils.ProgName+": ConnectByEnvironment failed:", err.Error())
-		os.Exit(1)
-	}
-}
-
-// NewConnector returns a connected Connector given the provided configuration
-func NewConnector(cfg Config) *Connector { // nolint:gocyclo
+// NewConnector returns a connected Connector given the provided configuration.
+// It returns an error if connection fails instead of calling os.Exit.
+func NewConnector(cfg Config) (*Connector, error) { // nolint:gocyclo
 	var defaultsFile string
 	connector := new(Connector)
 
 	if *cfg.UseEnvironment {
-		connector.ConnectByEnvironment()
+		connector.method = ConnectByEnvironment
+		if err := connector.Connect(); err != nil {
+			return nil, fmt.Errorf("ConnectByEnvironment: %w", err)
+		}
 	} else {
 		if *cfg.Host != "" || *cfg.Socket != "" {
 			log.Println("--host= or --socket= defined")
 			var config mysql_defaults_file.Config
 			if *cfg.Host != "" && *cfg.Socket != "" {
-				fmt.Println(utils.ProgName + ": Do not specify --host and --socket together")
-				os.Exit(1)
+				return nil, fmt.Errorf("do not specify --host and --socket together")
 			}
 			if *cfg.Host != "" {
 				config.Host = *cfg.Host
@@ -155,13 +126,11 @@ func NewConnector(cfg Config) *Connector { // nolint:gocyclo
 					// validate port number
 					port := *cfg.Port
 					if port < 0 || port > math.MaxUint16 {
-						fmt.Println(utils.ProgName+": Invalid port value", *cfg.Port)
-						os.Exit(1)
+						return nil, fmt.Errorf("invalid port value: %d", port)
 					}
 					config.Port = uint16(port) // nolint:gosec
 				} else {
-					fmt.Println(utils.ProgName + ": Do not specify --socket and --port together")
-					os.Exit(1)
+					return nil, fmt.Errorf("do not specify --socket and --port together")
 				}
 			}
 			if *cfg.Socket != "" {
@@ -173,7 +142,11 @@ func NewConnector(cfg Config) *Connector { // nolint:gocyclo
 			if *cfg.Password != "" {
 				config.Password = *cfg.Password
 			}
-			connector.ConnectByConfig(config)
+			connector.config = config
+			connector.method = ConnectByConfig
+			if err := connector.Connect(); err != nil {
+				return nil, fmt.Errorf("ConnectByConfig: %w", err)
+			}
 		} else {
 			// no host or socket provided so assume connecting by a defaults file.
 			// - if an explicit defaults-file is provided use that.
@@ -186,9 +159,13 @@ func NewConnector(cfg Config) *Connector { // nolint:gocyclo
 			} else {
 				log.Println("NewConnector: connecting by implicit defaults file")
 			}
-			connector.ConnectByDefaultsFile(defaultsFile)
+			connector.config = mysql_defaults_file.NewConfig(defaultsFile)
+			connector.method = ConnectByDefaultsFile
+			if err := connector.Connect(); err != nil {
+				return nil, fmt.Errorf("ConnectByDefaultsFile(%s): %w", defaultsFile, err)
+			}
 		}
 	}
 
-	return connector
+	return connector, nil
 }