Add sync => go-sync

sync/time/ntp/ntp.go

@@ -0,0 +1,51 @@
+// Package ntp provides ntp synchronized time
+package ntp
+
+import (
+	"context"
+	gotime "time"
+
+	"github.com/beevik/ntp"
+	"github.com/micro/go-micro/sync/time"
+)
+
+type ntpTime struct {
+	server string
+}
+
+type ntpServerKey struct{}
+
+func (n *ntpTime) Now() (gotime.Time, error) {
+	return ntp.Time(n.server)
+}
+
+// NewTime returns ntp time
+func NewTime(opts ...time.Option) time.Time {
+	options := time.Options{
+		Context: context.Background(),
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	server := "time.google.com"
+
+	if k, ok := options.Context.Value(ntpServerKey{}).(string); ok {
+		server = k
+	}
+
+	return &ntpTime{
+		server: server,
+	}
+}
+
+// WithServer sets the ntp server
+func WithServer(s string) time.Option {
+	return func(o *time.Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, ntpServerKey{}, s)
+	}
+}