Remove mutex and mutable driver map

Author: Harvey Lowndes

cmd/oci/main.go

@@ -20,7 +20,6 @@ import (
 	"os"
 	"path"
 	"strings"
-	"sync"
 
 	"github.com/oracle/oci-flexvolume-driver/pkg/flexvolume"
 	"github.com/oracle/oci-flexvolume-driver/pkg/oci/driver"
@@ -30,10 +29,8 @@ import (
 var version string
 var build string
 
-// All registered drivers.
 var (
-	driversMutex sync.Mutex
-	drivers      = make(map[string]flexvolume.Driver)
+	drivers = make(map[string]flexvolume.Driver)
 )
 
 // GetLogPath returns the default path to the driver log file.
@@ -45,7 +42,7 @@ func GetLogPath() string {
 	return path + "/oci_flexvolume_driver.log"
 }
 
-func loadRegisteredDrivers() {
+func registerDrivers() {
 	registerDriver("oci-bvs", &driver.OCIFlexvolumeDriver{})
 }
 
@@ -64,7 +61,7 @@ func main() {
 
 	log.Printf("OCI FlexVolume Driver version: %s (%s)", version, build)
 
-	loadRegisteredDrivers()
+	registerDrivers()
 
 	driver, err := getDriverFromArgs()
 	if err != nil {
@@ -75,7 +72,7 @@ func main() {
 }
 
 func getDriverFromArgs() (flexvolume.Driver, error) {
-	driver, err := getRegisteredDriver(flexvolume.DefaultSymlinkDirectory) //Block volume is default
+	driver, err := getDriver(flexvolume.DefaultSymlinkDirectory) //Block volume is default
 	if err != nil {
 		return nil, err
 	}
@@ -84,7 +81,7 @@ func getDriverFromArgs() (flexvolume.Driver, error) {
 	dir = string(strings.TrimPrefix(dir, "oracle~"))
 
 	if dir != "oci" && dir != flexvolume.DefaultSymlinkDirectory {
-		driver, err = getRegisteredDriver(dir)
+		driver, err = getDriver(dir)
 		if err != nil {
 			return nil, err
 		}
@@ -95,26 +92,16 @@ func getDriverFromArgs() (flexvolume.Driver, error) {
 	return driver, nil
 }
 
-// getRegisteredDriver returns an instance of the named driver, or nil if
-// the name is unknown. An error is thrown if the named driver is not found.
-func getRegisteredDriver(name string) (flexvolume.Driver, error) {
-	driversMutex.Lock()
-	defer driversMutex.Unlock()
-	f, found := drivers[name]
-	if !found {
-		return nil, fmt.Errorf("No driver found for %s", name)
+func registerDriver(name string, driver flexvolume.Driver) {
+	if drivers[name] == nil {
+		drivers[name] = driver
 	}
-	return f, nil
 }
 
-// registerDriver registers a flexvolume.Driver by name.  This
-// is expected to happen during app startup.
-func registerDriver(name string, driver flexvolume.Driver) {
-	driversMutex.Lock()
-	defer driversMutex.Unlock()
-	if _, found := drivers[name]; found {
-		log.Fatalf("Driver %q was registered twice", name)
+func getDriver(name string) (flexvolume.Driver, error) {
+	driver := drivers[name]
+	if driver == nil {
+		return nil, fmt.Errorf("could not find a registered driver for %s", name)
 	}
-	log.Printf("Registered driver %q", name)
-	drivers[name] = driver
+	return driver, nil
 }

pkg/flexvolume/flexvolume.go

@@ -185,7 +185,7 @@ func ExecDriver(driver Driver, args []string) DriverStatus {
 	// <driver executable> attach <json options> <node name>
 	case "attach":
 		if len(args) != 4 {
-			Failf("attach expected exactly 4 arguments; got ", args)
+			Failf("attach expected exactly 4 arguments; got %d ", len(args))
 		}
 
 		opts, err := processOpts(args[2])