Avoid having 2 goroutines to handle file changes

On goroutine was just waiting the goroutine handing the events
just to keep the "watcher" variable alive.
Move defer to event handling goroutine and avoid one goroutine.

Signed-off-by: Frediano Ziglio <fziglio@cyral.com>

viper.go

@@ -32,7 +32,6 @@ import (
 	"reflect"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 
 	"github.com/fsnotify/fsnotify"
@@ -341,19 +340,10 @@ func (v *Viper) OnConfigChange(run func(in fsnotify.Event)) {
 func WatchConfig() { v.WatchConfig() }
 
 func (v *Viper) WatchConfig() {
-	initWG := sync.WaitGroup{}
-	initWG.Add(1)
-	go func() {
-		watcher, err := newWatcher()
-		if err != nil {
-			log.Fatal(err)
-		}
-		defer watcher.Close()
 	// we have to watch the entire directory to pick up renames/atomic saves in a cross-platform way
 	filename, err := v.getConfigFile()
 	if err != nil {
 		log.Printf("error: %v\n", err)
-			initWG.Done()
 		return
 	}
 
@@ -361,14 +351,18 @@ func (v *Viper) WatchConfig() {
 	configDir, _ := filepath.Split(configFile)
 	realConfigFile, _ := filepath.EvalSymlinks(filename)
 
-		eventsWG := sync.WaitGroup{}
-		eventsWG.Add(1)
+	watcher, err := newWatcher()
+	if err != nil {
+		log.Fatal(err)
+		return
+	}
+
 	go func() {
+		defer watcher.Close()
 		for {
 			select {
 			case event, ok := <-watcher.Events:
 				if !ok { // 'Events' channel is closed
-						eventsWG.Done()
 					return
 				}
 				currentConfigFile, _ := filepath.EvalSymlinks(filename)
@@ -389,7 +383,6 @@ func (v *Viper) WatchConfig() {
 					}
 				} else if filepath.Clean(event.Name) == configFile &&
 					event.Op&fsnotify.Remove != 0 {
-						eventsWG.Done()
 					return
 				}
 
@@ -397,16 +390,11 @@ func (v *Viper) WatchConfig() {
 				if ok { // 'Errors' channel is not closed
 					log.Printf("watcher error: %v\n", err)
 				}
-					eventsWG.Done()
 				return
 			}
 		}
 	}()
 	watcher.Add(configDir)
-		initWG.Done()   // done initializing the watch in this go routine, so the parent routine can move on...
-		eventsWG.Wait() // now, wait for event loop to end in this go-routine...
-	}()
-	initWG.Wait() // make sure that the go routine above fully ended before returning
 }
 
 // SetConfigFile explicitly defines the path, name and extension of the config file.