refactor: move mock time to utils

internal/utils/time_now.go

@@ -0,0 +1,48 @@
+package utils
+
+import (
+	"time"
+
+	"github.com/yusing/go-proxy/internal/task"
+	"go.uber.org/atomic"
+)
+
+var (
+	TimeNow           = DefaultTimeNow
+	shouldCallTimeNow atomic.Bool
+	timeNowTicker     = time.NewTicker(shouldCallTimeNowInterval)
+	lastTimeNow       = time.Now()
+)
+
+const shouldCallTimeNowInterval = 100 * time.Millisecond
+
+func MockTimeNow(t time.Time) {
+	TimeNow = func() time.Time {
+		return t
+	}
+}
+
+// DefaultTimeNow is a time.Now wrapper that reduces the number of calls to time.Now
+// by caching the result and only allow calling time.Now when the ticker fires.
+//
+// Returned value may have +-100ms error.
+func DefaultTimeNow() time.Time {
+	if shouldCallTimeNow.Load() {
+		lastTimeNow = time.Now()
+		shouldCallTimeNow.Store(false)
+	}
+	return lastTimeNow
+}
+
+func init() {
+	go func() {
+		for {
+			select {
+			case <-task.RootContext().Done():
+				return
+			case <-timeNowTicker.C:
+				shouldCallTimeNow.Store(true)
+			}
+		}
+	}()
+}