daemon/active + watchdog: simplify control flow using explicit ActiveSideState

util/watchdog/watchdog.go

@@ -6,36 +6,26 @@ import (
 	"time"
 )
 
-type Progress struct {
+type KeepAlive struct {
+	mtx sync.Mutex
 	lastUpd time.Time
 }
 
-func (p *Progress) String() string {
-	return fmt.Sprintf("last update at %s", p.lastUpd)
-}
-
-func (p *Progress) madeProgressSince(p2 *Progress) bool {
-	if p.lastUpd.IsZero() && p2.lastUpd.IsZero() {
-		return false
+func (p *KeepAlive) String() string {
+	if p.lastUpd.IsZero() {
+		return fmt.Sprintf("never updated")
 	}
-	return p.lastUpd.After(p2.lastUpd)
-}
-
-type KeepAlive struct {
-	mtx sync.Mutex
-	p Progress
+	return fmt.Sprintf("last update at %s", p.lastUpd)
 }
 
 func (k *KeepAlive) MadeProgress() {
 	k.mtx.Lock()
 	defer k.mtx.Unlock()
-	k.p.lastUpd = time.Now()
+	k.lastUpd = time.Now()
 }
 
-func (k *KeepAlive) ExpectProgress(last *Progress) (madeProgress bool) {
+func (k *KeepAlive) CheckTimeout(timeout time.Duration, jitter time.Duration) (didTimeOut bool) {
 	k.mtx.Lock()
 	defer k.mtx.Unlock()
-	madeProgress = k.p.madeProgressSince(last)
-	*last = k.p
-	return madeProgress
+	return k.lastUpd.Add(timeout - jitter).Before(time.Now())
 }