service/scheduler: add Cron type

.golangci.yml

@@ -79,6 +79,7 @@ issues:
     - exported method +\.Close should have comment or be unexported
     - exported method .*Value\..+ should have comment or be unexported
     - exported method .+\.Init should have comment or be unexported
+    - exported method .+\.IsZero should have comment or be unexported
     - exported method .+\.Key should have comment or be unexported
     - exported method .+\.MarshalBinary should have comment or be unexported
     - exported method .+\.MarshalCQL should have comment or be unexported

pkg/service/scheduler/cron.go

@@ -0,0 +1,76 @@
+// Copyright (C) 2017 ScyllaDB
+
+package scheduler
+
+import (
+	"time"
+
+	"github.com/gocql/gocql"
+	"github.com/pkg/errors"
+	"github.com/scylladb/scylla-manager/pkg/scheduler"
+	"github.com/scylladb/scylla-manager/pkg/scheduler/trigger"
+)
+
+// Cron implements a trigger based on cron expression.
+// It supports the extended syntax including @monthly, @weekly, @daily, @midnight, @hourly, @every <time.Duration>.
+type Cron struct {
+	spec  []byte
+	inner scheduler.Trigger
+}
+
+func NewCron(spec string) (Cron, error) {
+	t, err := trigger.NewCron(spec)
+	if err != nil {
+		return Cron{}, err
+	}
+
+	return Cron{
+		spec:  []byte(spec),
+		inner: t,
+	}, nil
+}
+
+func NewCronEvery(d time.Duration) Cron {
+	c, _ := NewCron("@every " + d.String()) // nolint: errcheck
+	return c
+}
+
+// MustCron calls NewCron and panics on error.
+func MustCron(spec string) Cron {
+	c, err := NewCron(spec)
+	if err != nil {
+		panic(err)
+	}
+	return c
+}
+
+// Next implements scheduler.Trigger.
+func (c Cron) Next(now time.Time) time.Time {
+	return c.inner.Next(now)
+}
+
+func (c Cron) MarshalText() (text []byte, err error) {
+	return c.spec, nil
+}
+
+func (c *Cron) UnmarshalText(text []byte) error {
+	v, err := NewCron(string(text))
+	if err != nil {
+		return errors.Wrap(err, "cron")
+	}
+
+	*c = v
+	return nil
+}
+
+func (c Cron) MarshalCQL(info gocql.TypeInfo) ([]byte, error) {
+	return c.MarshalText()
+}
+
+func (c *Cron) UnmarshalCQL(info gocql.TypeInfo, data []byte) error {
+	return c.UnmarshalText(data)
+}
+
+func (c Cron) IsZero() bool {
+	return c.inner == nil
+}

pkg/service/scheduler/cron_test.go

@@ -0,0 +1,28 @@
+// Copyright (C) 2021 ScyllaDB
+
+package scheduler
+
+import (
+	"testing"
+	"time"
+)
+
+func TestCronMarshalUnmarshal(t *testing.T) {
+	spec := "@every 15s"
+
+	var cron Cron
+	if err := cron.UnmarshalText([]byte(spec)); err != nil {
+		t.Fatal(err)
+	}
+	b, _ := cron.MarshalText()
+	if string(b) != spec {
+		t.Fatalf("MarshalText() = %s, expected %s", string(b), spec)
+	}
+}
+
+func TestNewCronEvery(t *testing.T) {
+	c := NewCronEvery(15 * time.Second)
+	if c.IsZero() {
+		t.Fatal()
+	}
+}