Use defer to unlock mutex (#66)

* FIX: deadlock fix - mutex unlock via defer in GetOrSet

* FIX: move all mutex Unlocks into defer

* FIX: remove unnecessary new lines

cleaner.go

@@ -30,14 +30,13 @@ func (c *cleaner) start(r eremover, interval time.Duration) error {
 		return errors.New("imcache: interval must be greater than 0")
 	}
 	c.mu.Lock()
+	defer c.mu.Unlock()
 	if c.running {
-		c.mu.Unlock()
 		return errors.New("imcache: cleaner already running")
 	}
 	c.running = true
 	c.stopCh = make(chan struct{})
 	c.doneCh = make(chan struct{})
-	c.mu.Unlock()
 	go func() {
 		ticker := time.NewTicker(interval)
 		defer ticker.Stop()
@@ -56,13 +55,12 @@ func (c *cleaner) start(r eremover, interval time.Duration) error {
 
 func (c *cleaner) stop() {
 	c.mu.Lock()
+	defer c.mu.Unlock()
 	if !c.running {
-		c.mu.Unlock()
 		return
 	}
 	c.running = false
 	close(c.stopCh)
 	// Wait for the cleaner goroutine to stop while holding the lock.
 	<-c.doneCh
-	c.mu.Unlock()
 }