origin modules not active,thanks robfig#317

Author: penglj

constantdelay.go

@@ -26,6 +26,10 @@ func (schedule ConstantDelaySchedule) Next(t time.Time) time.Time {
 	return t.Add(schedule.Delay - time.Duration(t.Nanosecond())*time.Nanosecond)
 }
 
+func (schedule ConstantDelaySchedule) IsOnce() bool {
+	return false
+}
+
 // Prev returns the previous time this should be run.
 // This rounds so that the previous activation time will be on the second.
 func (schedule ConstantDelaySchedule) Prev(t time.Time) time.Time {

cron.go

@@ -54,6 +54,7 @@ type Schedule interface {
 
 	// Prev returns the previous activation time, earlier than the given time.
 	Prev(time.Time) time.Time
+	IsOnce() bool
 }
 
 // EntryID identifies an entry within a Cron instance
@@ -319,16 +320,26 @@ func (c *Cron) run() {
 				now = now.In(c.location)
 				c.logger.Info("wake", "now", now)
 
+				del := 0
+
 				// Run every entry whose next time was less than now
-				for _, e := range c.entries {
+				for k, e := range c.entries {
 					if e.Next.After(now) || e.Next.IsZero() {
 						break
 					}
+
 					c.startJob(e.WrappedJob)
 					e.Prev = e.Next
 					e.Next = e.Schedule.Next(now)
 					c.logger.Info("run", "now", now, "entry", e.ID, "next", e.Next)
+					// only run once
+					if e.Schedule.IsOnce() {
+						c.entries[k] = c.entries[del]
+						del++
+					}
+
 				}
+				c.entries = c.entries[del:]
 
 			case newEntry := <-c.add:
 				timer.Stop()

cron_test.go

@@ -545,6 +545,10 @@ func (*ZeroSchedule) Prev(time.Time) time.Time {
 	return time.Time{}
 }
 
+func (*ZeroSchedule) IsOnce() bool {
+	return false
+}
+
 // Tests that job without time does not run
 func TestJobWithZeroTimeDoesNotRun(t *testing.T) {
 	cron := newWithSeconds()

doc.go

@@ -24,6 +24,7 @@ them in their own goroutines.
 	c.AddFunc("CRON_TZ=Asia/Tokyo 30 04 * * *", func() { fmt.Println("Runs at 04:30 Tokyo time every day") })
 	c.AddFunc("@hourly",      func() { fmt.Println("Every hour, starting an hour from now") })
 	c.AddFunc("@every 1h30m", func() { fmt.Println("Every hour thirty, starting an hour thirty from now") })
+	c.AddFunc("@once 2020-06-02 17:04:31", func() { fmt.Println("Hello! Now is 2020-06-02 17:04:31") })
 	c.Start()
 	..
 	// Funcs are invoked in their own goroutine, asynchronously.

parser.go

@@ -358,7 +358,6 @@ func mustParseInt(expr string) (uint, error) {
 // getBits sets all bits in the range [min, max], modulo the given step size.
 func getBits(min, max, step uint) uint64 {
 	var bits uint64
-
 	// If step is 1, use shifts.
 	if step == 1 {
 		return ^(math.MaxUint64 << (max + 1)) & (math.MaxUint64 << min)
@@ -445,5 +444,35 @@ func parseDescriptor(descriptor string, loc *time.Location) (Schedule, error) {
 		return Every(duration), nil
 	}
 
+	const once = "@once "
+	if strings.HasPrefix(descriptor, once) {
+		runDate, err := time.Parse("2006-01-02 15:04:05", strings.Replace(descriptor, once, "", 1))
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse duration %s: %s", descriptor, err)
+		}
+
+		var (
+			second = uint(runDate.Second())
+			minute = uint(runDate.Minute())
+			hour   = uint(runDate.Hour())
+			dom    = uint(runDate.Day())
+			month  = uint(runDate.Month())
+			year   = uint(runDate.Year())
+		)
+
+		ret := &SpecSchedule{
+			Second:   uint64(second),
+			Minute:   uint64(minute),
+			Hour:     uint64(hour),
+			Dom:      uint64(dom),
+			Month:    uint64(month),
+			Year:     uint64(year),
+			Dow:      all(dow),
+			Once:     true,
+			Location: loc,
+		}
+		return ret, nil
+	}
+
 	return nil, fmt.Errorf("unrecognized descriptor: %s", descriptor)
 }

parser_test.go

@@ -320,7 +320,7 @@ func TestStandardSpecSchedule(t *testing.T) {
 	}{
 		{
 			expr:     "5 * * * *",
-			expected: &SpecSchedule{1 << seconds.min, 1 << 5, all(hours), all(dom), all(months), all(dow), time.Local},
+			expected: &SpecSchedule{1 << seconds.min, 1 << 5, all(hours), all(dom), all(months), all(dow), 0, false, time.Local},
 		},
 		{
 			expr:     "@every 5m",
@@ -359,15 +359,15 @@ func TestNoDescriptorParser(t *testing.T) {
 }
 
 func every5min(loc *time.Location) *SpecSchedule {
-	return &SpecSchedule{1 << 0, 1 << 5, all(hours), all(dom), all(months), all(dow), loc}
+	return &SpecSchedule{1 << 0, 1 << 5, all(hours), all(dom), all(months), all(dow), 0, false, loc}
 }
 
 func every5min5s(loc *time.Location) *SpecSchedule {
-	return &SpecSchedule{1 << 5, 1 << 5, all(hours), all(dom), all(months), all(dow), loc}
+	return &SpecSchedule{1 << 5, 1 << 5, all(hours), all(dom), all(months), all(dow), 0, false, loc}
 }
 
 func midnight(loc *time.Location) *SpecSchedule {
-	return &SpecSchedule{1, 1, 1, all(dom), all(months), all(dow), loc}
+	return &SpecSchedule{1, 1, 1, all(dom), all(months), all(dow), 0, false, loc}
 }
 
 func annual(loc *time.Location) *SpecSchedule {

spec.go

@@ -7,8 +7,8 @@ import (
 // SpecSchedule specifies a duty cycle (to the second granularity), based on a
 // traditional crontab specification. It is computed initially and stored as bit sets.
 type SpecSchedule struct {
-	Second, Minute, Hour, Dom, Month, Dow uint64
-
+	Second, Minute, Hour, Dom, Month, Dow, Year uint64
+	Once                                        bool
 	// Override location for this schedule.
 	Location *time.Location
 }
@@ -78,9 +78,18 @@ const (
 	starBit = 1 << 63
 )
 
+func (s *SpecSchedule) IsOnce() bool {
+	return s.Once
+}
+
 // Next returns the next time this schedule is activated, greater than the given
 // time.  If no time can be found to satisfy the schedule, return the zero time.
 func (s *SpecSchedule) Next(t time.Time) time.Time {
+	// Once Task is definite datetime
+	if s.Once {
+		return time.Date(int(s.Year), time.Month(s.Month), int(s.Dom), int(s.Hour), int(s.Minute), int(s.Second), 0, s.Location)
+	}
+
 	// General approach
 	//
 	// For Month, Day, Hour, Minute, Second: