split main package into subpackages

clock/clock.go

@@ -0,0 +1,50 @@
+package clock
+
+import (
+	"context"
+	"time"
+)
+
+const WALLCLOCK_PRECISION = 1 * time.Second
+
+func AfterWallClock(d time.Duration) <-chan time.Time {
+	ch := make(chan time.Time, 1)
+	deadline := time.Now().Add(d).Truncate(0)
+	after_ch := time.After(d)
+	ticker := time.NewTicker(WALLCLOCK_PRECISION)
+	go func() {
+		var t time.Time
+		defer ticker.Stop()
+		for {
+			select {
+			case t = <-after_ch:
+				ch <- t
+				return
+			case t = <-ticker.C:
+				if t.After(deadline) {
+					ch <- t
+					return
+				}
+			}
+		}
+	}()
+	return ch
+}
+
+func RunTicker(ctx context.Context, interval, retryInterval time.Duration, cb func(context.Context) error) {
+	go func() {
+		var err error
+		for {
+			nextInterval := interval
+			if err != nil {
+				nextInterval = retryInterval
+			}
+			select {
+			case <-ctx.Done():
+				return
+			case <-AfterWallClock(nextInterval):
+				err = cb(ctx)
+			}
+		}
+	}()
+}