Minor refactor

common/internalstate.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"sort"
 	"sync"
+	"sync/atomic"
 	"time"
 )
 
@@ -16,6 +17,8 @@ const (
 	DbStateInconsistent
 )
 
+var inShutdown int32
+
 // InternalStateColumn contains the data of a db column
 type InternalStateColumn struct {
 	Name       string    `json:"name"`
@@ -265,3 +268,13 @@ func UnpackInternalState(buf []byte) (*InternalState, error) {
 	}
 	return &is, nil
 }
+
+// SetInShutdown sets the internal state to in shutdown state
+func SetInShutdown() {
+	atomic.StoreInt32(&inShutdown, 1)
+}
+
+// IsInShutdown returns true if in application shutdown state
+func IsInShutdown() bool {
+	return atomic.LoadInt32(&inShutdown) != 0
+}

common/utils.go

@@ -0,0 +1,41 @@
+package common
+
+import (
+	"time"
+)
+
+// TickAndDebounce calls function f on trigger channel or with tickTime period (whatever is sooner) with debounce
+func TickAndDebounce(tickTime time.Duration, debounceTime time.Duration, trigger chan struct{}, f func()) {
+	timer := time.NewTimer(tickTime)
+	var firstDebounce time.Time
+Loop:
+	for {
+		select {
+		case _, ok := <-trigger:
+			if !timer.Stop() {
+				<-timer.C
+			}
+			// exit loop on closed input channel
+			if !ok {
+				break Loop
+			}
+			if firstDebounce.IsZero() {
+				firstDebounce = time.Now()
+			}
+			// debounce for up to debounceTime period
+			// afterwards execute immediately
+			if firstDebounce.Add(debounceTime).After(time.Now()) {
+				timer.Reset(debounceTime)
+			} else {
+				timer.Reset(0)
+			}
+		case <-timer.C:
+			// do the action, if not in shutdown, then start the loop again
+			if !IsInShutdown() {
+				f()
+			}
+			timer.Reset(tickTime)
+			firstDebounce = time.Time{}
+		}
+	}
+}