config: Rework autosave to be rearmed upon change

cmd/micro/micro.go

@@ -356,9 +356,9 @@ func main() {
 		log.Println(clipErr, " or change 'clipboard' option")
 	}
 
+	config.StartAutoSave()
 	if a := config.GetGlobalOption("autosave").(float64); a > 0 {
 		config.SetAutoTime(a)
-		config.StartAutoSave()
 	}
 
 	screen.Events = make(chan tcell.Event)

internal/action/command.go

@@ -553,7 +553,6 @@ func doSetGlobalOptionNative(option string, nativeValue interface{}) error {
 	} else if option == "autosave" {
 		if nativeValue.(float64) > 0 {
 			config.SetAutoTime(nativeValue.(float64))
-			config.StartAutoSave()
 		} else {
 			config.SetAutoTime(0)
 		}

internal/config/autosave.go

@@ -1,37 +1,49 @@
 package config
 
 import (
-	"sync"
 	"time"
 )
 
 var Autosave chan bool
-var autotime float64
-
-// lock for autosave
-var autolock sync.Mutex
+var autotime chan float64
 
 func init() {
 	Autosave = make(chan bool)
+	autotime = make(chan float64)
 }
 
 func SetAutoTime(a float64) {
-	autolock.Lock()
-	autotime = a
-	autolock.Unlock()
+	autotime <- a
 }
 
 func StartAutoSave() {
 	go func() {
+		var a float64
+		var t *time.Timer
+		var elapsed <-chan time.Time
 		for {
-			autolock.Lock()
-			a := autotime
-			autolock.Unlock()
-			if a <= 0 {
-				break
+			select {
+			case a = <-autotime:
+				if t != nil {
+					t.Stop()
+					for len(elapsed) > 0 {
+						<-elapsed
+					}
+				}
+				if a > 0 {
+					if t != nil {
+						t.Reset(time.Duration(a * float64(time.Second)))
+					} else {
+						t = time.NewTimer(time.Duration(a * float64(time.Second)))
+						elapsed = t.C
+					}
+				}
+			case <-elapsed:
+				if a > 0 {
+					t.Reset(time.Duration(a * float64(time.Second)))
+					Autosave <- true
+				}
 			}
-			time.Sleep(time.Duration(a * float64(time.Second)))
-			Autosave <- true
 		}
 	}()
 }