Move status table to cron package (#7370)

vendor/github.com/gogs/cron/cron.go

@@ -0,0 +1,269 @@
+package cron
+
+import (
+	"log"
+	"runtime"
+	"sort"
+	"time"
+)
+
+// Cron keeps track of any number of entries, invoking the associated func as
+// specified by the schedule. It may be started, stopped, and the entries may
+// be inspected while running.
+type Cron struct {
+	entries  []*Entry
+	stop     chan struct{}
+	add      chan *Entry
+	snapshot chan []*Entry
+	running  bool
+	ErrorLog *log.Logger
+	location *time.Location
+}
+
+// Job is an interface for submitted cron jobs.
+type Job interface {
+	Run()
+}
+
+// The Schedule describes a job's duty cycle.
+type Schedule interface {
+	// Return the next activation time, later than the given time.
+	// Next is invoked initially, and then each time the job is run.
+	Next(time.Time) time.Time
+}
+
+// Entry consists of a schedule and the func to execute on that schedule.
+type Entry struct {
+	Description string
+	Spec        string
+
+	// The schedule on which this job should be run.
+	Schedule Schedule
+
+	// The next time the job will run. This is the zero time if Cron has not been
+	// started or this entry's schedule is unsatisfiable
+	Next time.Time
+
+	// The last time this job was run. This is the zero time if the job has never
+	// been run.
+	Prev time.Time
+
+	// The Job to run.
+	Job Job
+
+	ExecTimes int // Execute times count.
+}
+
+// byTime is a wrapper for sorting the entry array by time
+// (with zero time at the end).
+type byTime []*Entry
+
+func (s byTime) Len() int      { return len(s) }
+func (s byTime) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+func (s byTime) Less(i, j int) bool {
+	// Two zero times should return false.
+	// Otherwise, zero is "greater" than any other time.
+	// (To sort it at the end of the list.)
+	if s[i].Next.IsZero() {
+		return false
+	}
+	if s[j].Next.IsZero() {
+		return true
+	}
+	return s[i].Next.Before(s[j].Next)
+}
+
+// New returns a new Cron job runner, in the Local time zone.
+func New() *Cron {
+	return NewWithLocation(time.Now().Location())
+}
+
+// NewWithLocation returns a new Cron job runner.
+func NewWithLocation(location *time.Location) *Cron {
+	return &Cron{
+		entries:  nil,
+		add:      make(chan *Entry),
+		stop:     make(chan struct{}),
+		snapshot: make(chan []*Entry),
+		running:  false,
+		ErrorLog: nil,
+		location: location,
+	}
+}
+
+// A wrapper that turns a func() into a cron.Job
+type FuncJob func()
+
+func (f FuncJob) Run() { f() }
+
+// AddFunc adds a func to the Cron to be run on the given schedule.
+func (c *Cron) AddFunc(desc, spec string, cmd func()) (*Entry, error) {
+	return c.AddJob(desc, spec, FuncJob(cmd))
+}
+
+// AddJob adds a Job to the Cron to be run on the given schedule.
+func (c *Cron) AddJob(desc, spec string, cmd Job) (*Entry, error) {
+	schedule, err := Parse(spec)
+	if err != nil {
+		return nil, err
+	}
+	return c.Schedule(desc, spec, schedule, cmd), nil
+}
+
+// Schedule adds a Job to the Cron to be run on the given schedule.
+func (c *Cron) Schedule(desc, spec string, schedule Schedule, cmd Job) *Entry {
+	entry := &Entry{
+		Description: desc,
+		Spec:        spec,
+		Schedule:    schedule,
+		Job:         cmd,
+	}
+	if c.running {
+		c.add <- entry
+	} else {
+		c.entries = append(c.entries, entry)
+	}
+	return entry
+}
+
+// Entries returns a snapshot of the cron entries.
+func (c *Cron) Entries() []*Entry {
+	if c.running {
+		c.snapshot <- nil
+		x := <-c.snapshot
+		return x
+	}
+	return c.entrySnapshot()
+}
+
+// Location gets the time zone location
+func (c *Cron) Location() *time.Location {
+	return c.location
+}
+
+// Start the cron scheduler in its own go-routine, or no-op if already started.
+func (c *Cron) Start() {
+	if c.running {
+		return
+	}
+	c.running = true
+	go c.run()
+}
+
+// Run the cron scheduler, or no-op if already running.
+func (c *Cron) Run() {
+	if c.running {
+		return
+	}
+	c.running = true
+	c.run()
+}
+
+func (c *Cron) runWithRecovery(j Job) {
+	defer func() {
+		if r := recover(); r != nil {
+			const size = 64 << 10
+			buf := make([]byte, size)
+			buf = buf[:runtime.Stack(buf, false)]
+			c.logf("cron: panic running job: %v\n%s", r, buf)
+		}
+	}()
+	j.Run()
+}
+
+// Run the scheduler. this is private just due to the need to synchronize
+// access to the 'running' state variable.
+func (c *Cron) run() {
+	// Figure out the next activation times for each entry.
+	now := c.now()
+	for _, entry := range c.entries {
+		entry.Next = entry.Schedule.Next(now)
+	}
+
+	for {
+		// Determine the next entry to run.
+		sort.Sort(byTime(c.entries))
+
+		var timer *time.Timer
+		if len(c.entries) == 0 || c.entries[0].Next.IsZero() {
+			// If there are no entries yet, just sleep - it still handles new entries
+			// and stop requests.
+			timer = time.NewTimer(100000 * time.Hour)
+		} else {
+			timer = time.NewTimer(c.entries[0].Next.Sub(now))
+		}
+
+		for {
+			select {
+			case now = <-timer.C:
+				now = now.In(c.location)
+				// Run every entry whose next time was less than now
+				for _, e := range c.entries {
+					if e.Next.After(now) || e.Next.IsZero() {
+						break
+					}
+					go c.runWithRecovery(e.Job)
+					e.ExecTimes++
+					e.Prev = e.Next
+					e.Next = e.Schedule.Next(now)
+				}
+
+			case newEntry := <-c.add:
+				timer.Stop()
+				now = c.now()
+				newEntry.Next = newEntry.Schedule.Next(now)
+				c.entries = append(c.entries, newEntry)
+
+			case <-c.snapshot:
+				c.snapshot <- c.entrySnapshot()
+				continue
+
+			case <-c.stop:
+				timer.Stop()
+				return
+			}
+
+			break
+		}
+	}
+}
+
+// Logs an error to stderr or to the configured error log
+func (c *Cron) logf(format string, args ...interface{}) {
+	if c.ErrorLog != nil {
+		c.ErrorLog.Printf(format, args...)
+	} else {
+		log.Printf(format, args...)
+	}
+}
+
+// Stop stops the cron scheduler if it is running; otherwise it does nothing.
+func (c *Cron) Stop() {
+	if !c.running {
+		return
+	}
+	c.stop <- struct{}{}
+	c.running = false
+}
+
+// entrySnapshot returns a copy of the current cron entry list.
+func (c *Cron) entrySnapshot() []*Entry {
+	entries := []*Entry{}
+	for _, e := range c.entries {
+		entries = append(entries, &Entry{
+			Description: e.Description,
+			Spec:        e.Spec,
+			Schedule:    e.Schedule,
+			Next:        e.Next,
+			Prev:        e.Prev,
+			Job:         e.Job,
+			ExecTimes:   e.ExecTimes,
+		})
+	}
+	return entries
+}
+
+// now returns current time in c location
+func (c *Cron) now() time.Time {
+	return time.Now().In(c.location)
+}