common

common/src/github.com/robfig/cron/README.md

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+[![GoDoc](http://godoc.org/github.com/robfig/cron?status.png)](http://godoc.org/github.com/robfig/cron) 
+[![Build Status](https://travis-ci.org/robfig/cron.svg?branch=master)](https://travis-ci.org/robfig/cron)

common/src/github.com/robfig/cron/constantdelay.go

@@ -0,0 +1,27 @@
+package cron
+
+import "time"
+
+// ConstantDelaySchedule represents a simple recurring duty cycle, e.g. "Every 5 minutes".
+// It does not support jobs more frequent than once a second.
+type ConstantDelaySchedule struct {
+	Delay time.Duration
+}
+
+// Every returns a crontab Schedule that activates once every duration.
+// Delays of less than a second are not supported (will round up to 1 second).
+// Any fields less than a Second are truncated.
+func Every(duration time.Duration) ConstantDelaySchedule {
+	if duration < time.Second {
+		duration = time.Second
+	}
+	return ConstantDelaySchedule{
+		Delay: duration - time.Duration(duration.Nanoseconds())%time.Second,
+	}
+}
+
+// Next returns the next time this should be run.
+// This rounds so that the next activation time will be on the second.
+func (schedule ConstantDelaySchedule) Next(t time.Time) time.Time {
+	return t.Add(schedule.Delay - time.Duration(t.Nanosecond())*time.Nanosecond)
+}

common/src/github.com/robfig/cron/constantdelay_test.go

@@ -0,0 +1,54 @@
+package cron
+
+import (
+	"testing"
+	"time"
+)
+
+func TestConstantDelayNext(t *testing.T) {
+	tests := []struct {
+		time     string
+		delay    time.Duration
+		expected string
+	}{
+		// Simple cases
+		{"Mon Jul 9 14:45 2012", 15*time.Minute + 50*time.Nanosecond, "Mon Jul 9 15:00 2012"},
+		{"Mon Jul 9 14:59 2012", 15 * time.Minute, "Mon Jul 9 15:14 2012"},
+		{"Mon Jul 9 14:59:59 2012", 15 * time.Minute, "Mon Jul 9 15:14:59 2012"},
+
+		// Wrap around hours
+		{"Mon Jul 9 15:45 2012", 35 * time.Minute, "Mon Jul 9 16:20 2012"},
+
+		// Wrap around days
+		{"Mon Jul 9 23:46 2012", 14 * time.Minute, "Tue Jul 10 00:00 2012"},
+		{"Mon Jul 9 23:45 2012", 35 * time.Minute, "Tue Jul 10 00:20 2012"},
+		{"Mon Jul 9 23:35:51 2012", 44*time.Minute + 24*time.Second, "Tue Jul 10 00:20:15 2012"},
+		{"Mon Jul 9 23:35:51 2012", 25*time.Hour + 44*time.Minute + 24*time.Second, "Thu Jul 11 01:20:15 2012"},
+
+		// Wrap around months
+		{"Mon Jul 9 23:35 2012", 91*24*time.Hour + 25*time.Minute, "Thu Oct 9 00:00 2012"},
+
+		// Wrap around minute, hour, day, month, and year
+		{"Mon Dec 31 23:59:45 2012", 15 * time.Second, "Tue Jan 1 00:00:00 2013"},
+
+		// Round to nearest second on the delay
+		{"Mon Jul 9 14:45 2012", 15*time.Minute + 50*time.Nanosecond, "Mon Jul 9 15:00 2012"},
+
+		// Round up to 1 second if the duration is less.
+		{"Mon Jul 9 14:45:00 2012", 15 * time.Millisecond, "Mon Jul 9 14:45:01 2012"},
+
+		// Round to nearest second when calculating the next time.
+		{"Mon Jul 9 14:45:00.005 2012", 15 * time.Minute, "Mon Jul 9 15:00 2012"},
+
+		// Round to nearest second for both.
+		{"Mon Jul 9 14:45:00.005 2012", 15*time.Minute + 50*time.Nanosecond, "Mon Jul 9 15:00 2012"},
+	}
+
+	for _, c := range tests {
+		actual := Every(c.delay).Next(getTime(c.time))
+		expected := getTime(c.expected)
+		if actual != expected {
+			t.Errorf("%s, \"%s\": (expected) %v != %v (actual)", c.time, c.delay, expected, actual)
+		}
+	}
+}

common/src/github.com/robfig/cron/cron.go

@@ -0,0 +1,259 @@
+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 {
+	// 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
+}
+
+// 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(spec string, cmd func()) error {
+	return c.AddJob(spec, FuncJob(cmd))
+}
+
+// AddJob adds a Job to the Cron to be run on the given schedule.
+func (c *Cron) AddJob(spec string, cmd Job) error {
+	schedule, err := Parse(spec)
+	if err != nil {
+		return err
+	}
+	c.Schedule(schedule, cmd)
+	return nil
+}
+
+// Schedule adds a Job to the Cron to be run on the given schedule.
+func (c *Cron) Schedule(schedule Schedule, cmd Job) {
+	entry := &Entry{
+		Schedule: schedule,
+		Job:      cmd,
+	}
+	if !c.running {
+		c.entries = append(c.entries, entry)
+		return
+	}
+
+	c.add <- 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.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{
+			Schedule: e.Schedule,
+			Next:     e.Next,
+			Prev:     e.Prev,
+			Job:      e.Job,
+		})
+	}
+	return entries
+}
+
+// now returns current time in c location
+func (c *Cron) now() time.Time {
+	return time.Now().In(c.location)
+}

common/src/github.com/robfig/cron/cron_test.go

@@ -0,0 +1,355 @@
+package cron
+
+import (
+	"fmt"
+	"sync"
+	"testing"
+	"time"
+)
+
+// Many tests schedule a job for every second, and then wait at most a second
+// for it to run.  This amount is just slightly larger than 1 second to
+// compensate for a few milliseconds of runtime.
+const OneSecond = 1*time.Second + 10*time.Millisecond
+
+func TestFuncPanicRecovery(t *testing.T) {
+	cron := New()
+	cron.Start()
+	defer cron.Stop()
+	cron.AddFunc("* * * * * ?", func() { panic("YOLO") })
+
+	select {
+	case <-time.After(OneSecond):
+		return
+	}
+}
+
+type DummyJob struct{}
+
+func (d DummyJob) Run() {
+	panic("YOLO")
+}
+
+func TestJobPanicRecovery(t *testing.T) {
+	var job DummyJob
+
+	cron := New()
+	cron.Start()
+	defer cron.Stop()
+	cron.AddJob("* * * * * ?", job)
+
+	select {
+	case <-time.After(OneSecond):
+		return
+	}
+}
+
+// Start and stop cron with no entries.
+func TestNoEntries(t *testing.T) {
+	cron := New()
+	cron.Start()
+
+	select {
+	case <-time.After(OneSecond):
+		t.Fatal("expected cron will be stopped immediately")
+	case <-stop(cron):
+	}
+}
+
+// Start, stop, then add an entry. Verify entry doesn't run.
+func TestStopCausesJobsToNotRun(t *testing.T) {
+	wg := &sync.WaitGroup{}
+	wg.Add(1)
+
+	cron := New()
+	cron.Start()
+	cron.Stop()
+	cron.AddFunc("* * * * * ?", func() { wg.Done() })
+
+	select {
+	case <-time.After(OneSecond):
+		// No job ran!
+	case <-wait(wg):
+		t.Fatal("expected stopped cron does not run any job")
+	}
+}
+
+// Add a job, start cron, expect it runs.
+func TestAddBeforeRunning(t *testing.T) {
+	wg := &sync.WaitGroup{}
+	wg.Add(1)
+
+	cron := New()
+	cron.AddFunc("* * * * * ?", func() { wg.Done() })
+	cron.Start()
+	defer cron.Stop()
+
+	// Give cron 2 seconds to run our job (which is always activated).
+	select {
+	case <-time.After(OneSecond):
+		t.Fatal("expected job runs")
+	case <-wait(wg):
+	}
+}
+
+// Start cron, add a job, expect it runs.
+func TestAddWhileRunning(t *testing.T) {
+	wg := &sync.WaitGroup{}
+	wg.Add(1)
+
+	cron := New()
+	cron.Start()
+	defer cron.Stop()
+	cron.AddFunc("* * * * * ?", func() { wg.Done() })
+
+	select {
+	case <-time.After(OneSecond):
+		t.Fatal("expected job runs")
+	case <-wait(wg):
+	}
+}
+
+// Test for #34. Adding a job after calling start results in multiple job invocations
+func TestAddWhileRunningWithDelay(t *testing.T) {
+	cron := New()
+	cron.Start()
+	defer cron.Stop()
+	time.Sleep(5 * time.Second)
+	var calls = 0
+	cron.AddFunc("* * * * * *", func() { calls += 1 })
+
+	<-time.After(OneSecond)
+	if calls != 1 {
+		t.Errorf("called %d times, expected 1\n", calls)
+	}
+}
+
+// Test timing with Entries.
+func TestSnapshotEntries(t *testing.T) {
+	wg := &sync.WaitGroup{}
+	wg.Add(1)
+
+	cron := New()
+	cron.AddFunc("@every 2s", func() { wg.Done() })
+	cron.Start()
+	defer cron.Stop()
+
+	// Cron should fire in 2 seconds. After 1 second, call Entries.
+	select {
+	case <-time.After(OneSecond):
+		cron.Entries()
+	}
+
+	// Even though Entries was called, the cron should fire at the 2 second mark.
+	select {
+	case <-time.After(OneSecond):
+		t.Error("expected job runs at 2 second mark")
+	case <-wait(wg):
+	}
+
+}
+
+// Test that the entries are correctly sorted.
+// Add a bunch of long-in-the-future entries, and an immediate entry, and ensure
+// that the immediate entry runs immediately.
+// Also: Test that multiple jobs run in the same instant.
+func TestMultipleEntries(t *testing.T) {
+	wg := &sync.WaitGroup{}
+	wg.Add(2)
+
+	cron := New()
+	cron.AddFunc("0 0 0 1 1 ?", func() {})
+	cron.AddFunc("* * * * * ?", func() { wg.Done() })
+	cron.AddFunc("0 0 0 31 12 ?", func() {})
+	cron.AddFunc("* * * * * ?", func() { wg.Done() })
+
+	cron.Start()
+	defer cron.Stop()
+
+	select {
+	case <-time.After(OneSecond):
+		t.Error("expected job run in proper order")
+	case <-wait(wg):
+	}
+}
+
+// Test running the same job twice.
+func TestRunningJobTwice(t *testing.T) {
+	wg := &sync.WaitGroup{}
+	wg.Add(2)
+
+	cron := New()
+	cron.AddFunc("0 0 0 1 1 ?", func() {})
+	cron.AddFunc("0 0 0 31 12 ?", func() {})
+	cron.AddFunc("* * * * * ?", func() { wg.Done() })
+
+	cron.Start()
+	defer cron.Stop()
+
+	select {
+	case <-time.After(2 * OneSecond):
+		t.Error("expected job fires 2 times")
+	case <-wait(wg):
+	}
+}
+
+func TestRunningMultipleSchedules(t *testing.T) {
+	wg := &sync.WaitGroup{}
+	wg.Add(2)
+
+	cron := New()
+	cron.AddFunc("0 0 0 1 1 ?", func() {})
+	cron.AddFunc("0 0 0 31 12 ?", func() {})
+	cron.AddFunc("* * * * * ?", func() { wg.Done() })
+	cron.Schedule(Every(time.Minute), FuncJob(func() {}))
+	cron.Schedule(Every(time.Second), FuncJob(func() { wg.Done() }))
+	cron.Schedule(Every(time.Hour), FuncJob(func() {}))
+
+	cron.Start()
+	defer cron.Stop()
+
+	select {
+	case <-time.After(2 * OneSecond):
+		t.Error("expected job fires 2 times")
+	case <-wait(wg):
+	}
+}
+
+// Test that the cron is run in the local time zone (as opposed to UTC).
+func TestLocalTimezone(t *testing.T) {
+	wg := &sync.WaitGroup{}
+	wg.Add(2)
+
+	now := time.Now()
+	spec := fmt.Sprintf("%d,%d %d %d %d %d ?",
+		now.Second()+1, now.Second()+2, now.Minute(), now.Hour(), now.Day(), now.Month())
+
+	cron := New()
+	cron.AddFunc(spec, func() { wg.Done() })
+	cron.Start()
+	defer cron.Stop()
+
+	select {
+	case <-time.After(OneSecond * 2):
+		t.Error("expected job fires 2 times")
+	case <-wait(wg):
+	}
+}
+
+// Test that the cron is run in the given time zone (as opposed to local).
+func TestNonLocalTimezone(t *testing.T) {
+	wg := &sync.WaitGroup{}
+	wg.Add(2)
+
+	loc, err := time.LoadLocation("Atlantic/Cape_Verde")
+	if err != nil {
+		fmt.Printf("Failed to load time zone Atlantic/Cape_Verde: %+v", err)
+		t.Fail()
+	}
+
+	now := time.Now().In(loc)
+	spec := fmt.Sprintf("%d,%d %d %d %d %d ?",
+		now.Second()+1, now.Second()+2, now.Minute(), now.Hour(), now.Day(), now.Month())
+
+	cron := NewWithLocation(loc)
+	cron.AddFunc(spec, func() { wg.Done() })
+	cron.Start()
+	defer cron.Stop()
+
+	select {
+	case <-time.After(OneSecond * 2):
+		t.Error("expected job fires 2 times")
+	case <-wait(wg):
+	}
+}
+
+// Test that calling stop before start silently returns without
+// blocking the stop channel.
+func TestStopWithoutStart(t *testing.T) {
+	cron := New()
+	cron.Stop()
+}
+
+type testJob struct {
+	wg   *sync.WaitGroup
+	name string
+}
+
+func (t testJob) Run() {
+	t.wg.Done()
+}
+
+// Simple test using Runnables.
+func TestJob(t *testing.T) {
+	wg := &sync.WaitGroup{}
+	wg.Add(1)
+
+	cron := New()
+	cron.AddJob("0 0 0 30 Feb ?", testJob{wg, "job0"})
+	cron.AddJob("0 0 0 1 1 ?", testJob{wg, "job1"})
+	cron.AddJob("* * * * * ?", testJob{wg, "job2"})
+	cron.AddJob("1 0 0 1 1 ?", testJob{wg, "job3"})
+	cron.Schedule(Every(5*time.Second+5*time.Nanosecond), testJob{wg, "job4"})
+	cron.Schedule(Every(5*time.Minute), testJob{wg, "job5"})
+
+	cron.Start()
+	defer cron.Stop()
+
+	select {
+	case <-time.After(OneSecond):
+		t.FailNow()
+	case <-wait(wg):
+	}
+
+	// Ensure the entries are in the right order.
+	expecteds := []string{"job2", "job4", "job5", "job1", "job3", "job0"}
+
+	var actuals []string
+	for _, entry := range cron.Entries() {
+		actuals = append(actuals, entry.Job.(testJob).name)
+	}
+
+	for i, expected := range expecteds {
+		if actuals[i] != expected {
+			t.Fatalf("Jobs not in the right order.  (expected) %s != %s (actual)", expecteds, actuals)
+		}
+	}
+}
+
+type ZeroSchedule struct{}
+
+func (*ZeroSchedule) Next(time.Time) time.Time {
+	return time.Time{}
+}
+
+// Tests that job without time does not run
+func TestJobWithZeroTimeDoesNotRun(t *testing.T) {
+	cron := New()
+	calls := 0
+	cron.AddFunc("* * * * * *", func() { calls += 1 })
+	cron.Schedule(new(ZeroSchedule), FuncJob(func() { t.Error("expected zero task will not run") }))
+	cron.Start()
+	defer cron.Stop()
+	<-time.After(OneSecond)
+	if calls != 1 {
+		t.Errorf("called %d times, expected 1\n", calls)
+	}
+}
+
+func wait(wg *sync.WaitGroup) chan bool {
+	ch := make(chan bool)
+	go func() {
+		wg.Wait()
+		ch <- true
+	}()
+	return ch
+}
+
+func stop(cron *Cron) chan bool {
+	ch := make(chan bool)
+	go func() {
+		cron.Stop()
+		ch <- true
+	}()
+	return ch
+}

common/src/github.com/robfig/cron/doc.go

@@ -0,0 +1,129 @@
+/*
+Package cron implements a cron spec parser and job runner.
+
+Usage
+
+Callers may register Funcs to be invoked on a given schedule.  Cron will run
+them in their own goroutines.
+
+	c := cron.New()
+	c.AddFunc("0 30 * * * *", func() { fmt.Println("Every hour on the half hour") })
+	c.AddFunc("@hourly",      func() { fmt.Println("Every hour") })
+	c.AddFunc("@every 1h30m", func() { fmt.Println("Every hour thirty") })
+	c.Start()
+	..
+	// Funcs are invoked in their own goroutine, asynchronously.
+	...
+	// Funcs may also be added to a running Cron
+	c.AddFunc("@daily", func() { fmt.Println("Every day") })
+	..
+	// Inspect the cron job entries' next and previous run times.
+	inspect(c.Entries())
+	..
+	c.Stop()  // Stop the scheduler (does not stop any jobs already running).
+
+CRON Expression Format
+
+A cron expression represents a set of times, using 6 space-separated fields.
+
+	Field name   | Mandatory? | Allowed values  | Allowed special characters
+	----------   | ---------- | --------------  | --------------------------
+	Seconds      | Yes        | 0-59            | * / , -
+	Minutes      | Yes        | 0-59            | * / , -
+	Hours        | Yes        | 0-23            | * / , -
+	Day of month | Yes        | 1-31            | * / , - ?
+	Month        | Yes        | 1-12 or JAN-DEC | * / , -
+	Day of week  | Yes        | 0-6 or SUN-SAT  | * / , - ?
+
+Note: Month and Day-of-week field values are case insensitive.  "SUN", "Sun",
+and "sun" are equally accepted.
+
+Special Characters
+
+Asterisk ( * )
+
+The asterisk indicates that the cron expression will match for all values of the
+field; e.g., using an asterisk in the 5th field (month) would indicate every
+month.
+
+Slash ( / )
+
+Slashes are used to describe increments of ranges. For example 3-59/15 in the
+1st field (minutes) would indicate the 3rd minute of the hour and every 15
+minutes thereafter. The form "*\/..." is equivalent to the form "first-last/...",
+that is, an increment over the largest possible range of the field.  The form
+"N/..." is accepted as meaning "N-MAX/...", that is, starting at N, use the
+increment until the end of that specific range.  It does not wrap around.
+
+Comma ( , )
+
+Commas are used to separate items of a list. For example, using "MON,WED,FRI" in
+the 5th field (day of week) would mean Mondays, Wednesdays and Fridays.
+
+Hyphen ( - )
+
+Hyphens are used to define ranges. For example, 9-17 would indicate every
+hour between 9am and 5pm inclusive.
+
+Question mark ( ? )
+
+Question mark may be used instead of '*' for leaving either day-of-month or
+day-of-week blank.
+
+Predefined schedules
+
+You may use one of several pre-defined schedules in place of a cron expression.
+
+	Entry                  | Description                                | Equivalent To
+	-----                  | -----------                                | -------------
+	@yearly (or @annually) | Run once a year, midnight, Jan. 1st        | 0 0 0 1 1 *
+	@monthly               | Run once a month, midnight, first of month | 0 0 0 1 * *
+	@weekly                | Run once a week, midnight on Sunday        | 0 0 0 * * 0
+	@daily (or @midnight)  | Run once a day, midnight                   | 0 0 0 * * *
+	@hourly                | Run once an hour, beginning of hour        | 0 0 * * * *
+
+Intervals
+
+You may also schedule a job to execute at fixed intervals, starting at the time it's added 
+or cron is run. This is supported by formatting the cron spec like this:
+
+    @every <duration>
+
+where "duration" is a string accepted by time.ParseDuration
+(http://golang.org/pkg/time/#ParseDuration).
+
+For example, "@every 1h30m10s" would indicate a schedule that activates immediately,
+and then every 1 hour, 30 minutes, 10 seconds.
+
+Note: The interval does not take the job runtime into account.  For example,
+if a job takes 3 minutes to run, and it is scheduled to run every 5 minutes,
+it will have only 2 minutes of idle time between each run.
+
+Time zones
+
+All interpretation and scheduling is done in the machine's local time zone (as
+provided by the Go time package (http://www.golang.org/pkg/time).
+
+Be aware that jobs scheduled during daylight-savings leap-ahead transitions will
+not be run!
+
+Thread safety
+
+Since the Cron service runs concurrently with the calling code, some amount of
+care must be taken to ensure proper synchronization.
+
+All cron methods are designed to be correctly synchronized as long as the caller
+ensures that invocations have a clear happens-before ordering between them.
+
+Implementation
+
+Cron entries are stored in an array, sorted by their next activation time.  Cron
+sleeps until the next job is due to be run.
+
+Upon waking:
+ - it runs each entry that is active on that second
+ - it calculates the next run times for the jobs that were run
+ - it re-sorts the array of entries by next activation time.
+ - it goes to sleep until the soonest job.
+*/
+package cron

common/src/github.com/robfig/cron/parser.go

@@ -0,0 +1,380 @@
+package cron
+
+import (
+	"fmt"
+	"math"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Configuration options for creating a parser. Most options specify which
+// fields should be included, while others enable features. If a field is not
+// included the parser will assume a default value. These options do not change
+// the order fields are parse in.
+type ParseOption int
+
+const (
+	Second      ParseOption = 1 << iota // Seconds field, default 0
+	Minute                              // Minutes field, default 0
+	Hour                                // Hours field, default 0
+	Dom                                 // Day of month field, default *
+	Month                               // Month field, default *
+	Dow                                 // Day of week field, default *
+	DowOptional                         // Optional day of week field, default *
+	Descriptor                          // Allow descriptors such as @monthly, @weekly, etc.
+)
+
+var places = []ParseOption{
+	Second,
+	Minute,
+	Hour,
+	Dom,
+	Month,
+	Dow,
+}
+
+var defaults = []string{
+	"0",
+	"0",
+	"0",
+	"*",
+	"*",
+	"*",
+}
+
+// A custom Parser that can be configured.
+type Parser struct {
+	options   ParseOption
+	optionals int
+}
+
+// Creates a custom Parser with custom options.
+//
+//  // Standard parser without descriptors
+//  specParser := NewParser(Minute | Hour | Dom | Month | Dow)
+//  sched, err := specParser.Parse("0 0 15 */3 *")
+//
+//  // Same as above, just excludes time fields
+//  subsParser := NewParser(Dom | Month | Dow)
+//  sched, err := specParser.Parse("15 */3 *")
+//
+//  // Same as above, just makes Dow optional
+//  subsParser := NewParser(Dom | Month | DowOptional)
+//  sched, err := specParser.Parse("15 */3")
+//
+func NewParser(options ParseOption) Parser {
+	optionals := 0
+	if options&DowOptional > 0 {
+		options |= Dow
+		optionals++
+	}
+	return Parser{options, optionals}
+}
+
+// Parse returns a new crontab schedule representing the given spec.
+// It returns a descriptive error if the spec is not valid.
+// It accepts crontab specs and features configured by NewParser.
+func (p Parser) Parse(spec string) (Schedule, error) {
+	if len(spec) == 0 {
+		return nil, fmt.Errorf("Empty spec string")
+	}
+	if spec[0] == '@' && p.options&Descriptor > 0 {
+		return parseDescriptor(spec)
+	}
+
+	// Figure out how many fields we need
+	max := 0
+	for _, place := range places {
+		if p.options&place > 0 {
+			max++
+		}
+	}
+	min := max - p.optionals
+
+	// Split fields on whitespace
+	fields := strings.Fields(spec)
+
+	// Validate number of fields
+	if count := len(fields); count < min || count > max {
+		if min == max {
+			return nil, fmt.Errorf("Expected exactly %d fields, found %d: %s", min, count, spec)
+		}
+		return nil, fmt.Errorf("Expected %d to %d fields, found %d: %s", min, max, count, spec)
+	}
+
+	// Fill in missing fields
+	fields = expandFields(fields, p.options)
+
+	var err error
+	field := func(field string, r bounds) uint64 {
+		if err != nil {
+			return 0
+		}
+		var bits uint64
+		bits, err = getField(field, r)
+		return bits
+	}
+
+	var (
+		second     = field(fields[0], seconds)
+		minute     = field(fields[1], minutes)
+		hour       = field(fields[2], hours)
+		dayofmonth = field(fields[3], dom)
+		month      = field(fields[4], months)
+		dayofweek  = field(fields[5], dow)
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return &SpecSchedule{
+		Second: second,
+		Minute: minute,
+		Hour:   hour,
+		Dom:    dayofmonth,
+		Month:  month,
+		Dow:    dayofweek,
+	}, nil
+}
+
+func expandFields(fields []string, options ParseOption) []string {
+	n := 0
+	count := len(fields)
+	expFields := make([]string, len(places))
+	copy(expFields, defaults)
+	for i, place := range places {
+		if options&place > 0 {
+			expFields[i] = fields[n]
+			n++
+		}
+		if n == count {
+			break
+		}
+	}
+	return expFields
+}
+
+var standardParser = NewParser(
+	Minute | Hour | Dom | Month | Dow | Descriptor,
+)
+
+// ParseStandard returns a new crontab schedule representing the given standardSpec
+// (https://en.wikipedia.org/wiki/Cron). It differs from Parse requiring to always
+// pass 5 entries representing: minute, hour, day of month, month and day of week,
+// in that order. It returns a descriptive error if the spec is not valid.
+//
+// It accepts
+//   - Standard crontab specs, e.g. "* * * * ?"
+//   - Descriptors, e.g. "@midnight", "@every 1h30m"
+func ParseStandard(standardSpec string) (Schedule, error) {
+	return standardParser.Parse(standardSpec)
+}
+
+var defaultParser = NewParser(
+	Second | Minute | Hour | Dom | Month | DowOptional | Descriptor,
+)
+
+// Parse returns a new crontab schedule representing the given spec.
+// It returns a descriptive error if the spec is not valid.
+//
+// It accepts
+//   - Full crontab specs, e.g. "* * * * * ?"
+//   - Descriptors, e.g. "@midnight", "@every 1h30m"
+func Parse(spec string) (Schedule, error) {
+	return defaultParser.Parse(spec)
+}
+
+// getField returns an Int with the bits set representing all of the times that
+// the field represents or error parsing field value.  A "field" is a comma-separated
+// list of "ranges".
+func getField(field string, r bounds) (uint64, error) {
+	var bits uint64
+	ranges := strings.FieldsFunc(field, func(r rune) bool { return r == ',' })
+	for _, expr := range ranges {
+		bit, err := getRange(expr, r)
+		if err != nil {
+			return bits, err
+		}
+		bits |= bit
+	}
+	return bits, nil
+}
+
+// getRange returns the bits indicated by the given expression:
+//   number | number "-" number [ "/" number ]
+// or error parsing range.
+func getRange(expr string, r bounds) (uint64, error) {
+	var (
+		start, end, step uint
+		rangeAndStep     = strings.Split(expr, "/")
+		lowAndHigh       = strings.Split(rangeAndStep[0], "-")
+		singleDigit      = len(lowAndHigh) == 1
+		err              error
+	)
+
+	var extra uint64
+	if lowAndHigh[0] == "*" || lowAndHigh[0] == "?" {
+		start = r.min
+		end = r.max
+		extra = starBit
+	} else {
+		start, err = parseIntOrName(lowAndHigh[0], r.names)
+		if err != nil {
+			return 0, err
+		}
+		switch len(lowAndHigh) {
+		case 1:
+			end = start
+		case 2:
+			end, err = parseIntOrName(lowAndHigh[1], r.names)
+			if err != nil {
+				return 0, err
+			}
+		default:
+			return 0, fmt.Errorf("Too many hyphens: %s", expr)
+		}
+	}
+
+	switch len(rangeAndStep) {
+	case 1:
+		step = 1
+	case 2:
+		step, err = mustParseInt(rangeAndStep[1])
+		if err != nil {
+			return 0, err
+		}
+
+		// Special handling: "N/step" means "N-max/step".
+		if singleDigit {
+			end = r.max
+		}
+	default:
+		return 0, fmt.Errorf("Too many slashes: %s", expr)
+	}
+
+	if start < r.min {
+		return 0, fmt.Errorf("Beginning of range (%d) below minimum (%d): %s", start, r.min, expr)
+	}
+	if end > r.max {
+		return 0, fmt.Errorf("End of range (%d) above maximum (%d): %s", end, r.max, expr)
+	}
+	if start > end {
+		return 0, fmt.Errorf("Beginning of range (%d) beyond end of range (%d): %s", start, end, expr)
+	}
+	if step == 0 {
+		return 0, fmt.Errorf("Step of range should be a positive number: %s", expr)
+	}
+
+	return getBits(start, end, step) | extra, nil
+}
+
+// parseIntOrName returns the (possibly-named) integer contained in expr.
+func parseIntOrName(expr string, names map[string]uint) (uint, error) {
+	if names != nil {
+		if namedInt, ok := names[strings.ToLower(expr)]; ok {
+			return namedInt, nil
+		}
+	}
+	return mustParseInt(expr)
+}
+
+// mustParseInt parses the given expression as an int or returns an error.
+func mustParseInt(expr string) (uint, error) {
+	num, err := strconv.Atoi(expr)
+	if err != nil {
+		return 0, fmt.Errorf("Failed to parse int from %s: %s", expr, err)
+	}
+	if num < 0 {
+		return 0, fmt.Errorf("Negative number (%d) not allowed: %s", num, expr)
+	}
+
+	return uint(num), nil
+}
+
+// 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)
+	}
+
+	// Else, use a simple loop.
+	for i := min; i <= max; i += step {
+		bits |= 1 << i
+	}
+	return bits
+}
+
+// all returns all bits within the given bounds.  (plus the star bit)
+func all(r bounds) uint64 {
+	return getBits(r.min, r.max, 1) | starBit
+}
+
+// parseDescriptor returns a predefined schedule for the expression, or error if none matches.
+func parseDescriptor(descriptor string) (Schedule, error) {
+	switch descriptor {
+	case "@yearly", "@annually":
+		return &SpecSchedule{
+			Second: 1 << seconds.min,
+			Minute: 1 << minutes.min,
+			Hour:   1 << hours.min,
+			Dom:    1 << dom.min,
+			Month:  1 << months.min,
+			Dow:    all(dow),
+		}, nil
+
+	case "@monthly":
+		return &SpecSchedule{
+			Second: 1 << seconds.min,
+			Minute: 1 << minutes.min,
+			Hour:   1 << hours.min,
+			Dom:    1 << dom.min,
+			Month:  all(months),
+			Dow:    all(dow),
+		}, nil
+
+	case "@weekly":
+		return &SpecSchedule{
+			Second: 1 << seconds.min,
+			Minute: 1 << minutes.min,
+			Hour:   1 << hours.min,
+			Dom:    all(dom),
+			Month:  all(months),
+			Dow:    1 << dow.min,
+		}, nil
+
+	case "@daily", "@midnight":
+		return &SpecSchedule{
+			Second: 1 << seconds.min,
+			Minute: 1 << minutes.min,
+			Hour:   1 << hours.min,
+			Dom:    all(dom),
+			Month:  all(months),
+			Dow:    all(dow),
+		}, nil
+
+	case "@hourly":
+		return &SpecSchedule{
+			Second: 1 << seconds.min,
+			Minute: 1 << minutes.min,
+			Hour:   all(hours),
+			Dom:    all(dom),
+			Month:  all(months),
+			Dow:    all(dow),
+		}, nil
+	}
+
+	const every = "@every "
+	if strings.HasPrefix(descriptor, every) {
+		duration, err := time.ParseDuration(descriptor[len(every):])
+		if err != nil {
+			return nil, fmt.Errorf("Failed to parse duration %s: %s", descriptor, err)
+		}
+		return Every(duration), nil
+	}
+
+	return nil, fmt.Errorf("Unrecognized descriptor: %s", descriptor)
+}

common/src/github.com/robfig/cron/parser_test.go

@@ -0,0 +1,234 @@
+package cron
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestRange(t *testing.T) {
+	zero := uint64(0)
+	ranges := []struct {
+		expr     string
+		min, max uint
+		expected uint64
+		err      string
+	}{
+		{"5", 0, 7, 1 << 5, ""},
+		{"0", 0, 7, 1 << 0, ""},
+		{"7", 0, 7, 1 << 7, ""},
+
+		{"5-5", 0, 7, 1 << 5, ""},
+		{"5-6", 0, 7, 1<<5 | 1<<6, ""},
+		{"5-7", 0, 7, 1<<5 | 1<<6 | 1<<7, ""},
+
+		{"5-6/2", 0, 7, 1 << 5, ""},
+		{"5-7/2", 0, 7, 1<<5 | 1<<7, ""},
+		{"5-7/1", 0, 7, 1<<5 | 1<<6 | 1<<7, ""},
+
+		{"*", 1, 3, 1<<1 | 1<<2 | 1<<3 | starBit, ""},
+		{"*/2", 1, 3, 1<<1 | 1<<3 | starBit, ""},
+
+		{"5--5", 0, 0, zero, "Too many hyphens"},
+		{"jan-x", 0, 0, zero, "Failed to parse int from"},
+		{"2-x", 1, 5, zero, "Failed to parse int from"},
+		{"*/-12", 0, 0, zero, "Negative number"},
+		{"*//2", 0, 0, zero, "Too many slashes"},
+		{"1", 3, 5, zero, "below minimum"},
+		{"6", 3, 5, zero, "above maximum"},
+		{"5-3", 3, 5, zero, "beyond end of range"},
+		{"*/0", 0, 0, zero, "should be a positive number"},
+	}
+
+	for _, c := range ranges {
+		actual, err := getRange(c.expr, bounds{c.min, c.max, nil})
+		if len(c.err) != 0 && (err == nil || !strings.Contains(err.Error(), c.err)) {
+			t.Errorf("%s => expected %v, got %v", c.expr, c.err, err)
+		}
+		if len(c.err) == 0 && err != nil {
+			t.Errorf("%s => unexpected error %v", c.expr, err)
+		}
+		if actual != c.expected {
+			t.Errorf("%s => expected %d, got %d", c.expr, c.expected, actual)
+		}
+	}
+}
+
+func TestField(t *testing.T) {
+	fields := []struct {
+		expr     string
+		min, max uint
+		expected uint64
+	}{
+		{"5", 1, 7, 1 << 5},
+		{"5,6", 1, 7, 1<<5 | 1<<6},
+		{"5,6,7", 1, 7, 1<<5 | 1<<6 | 1<<7},
+		{"1,5-7/2,3", 1, 7, 1<<1 | 1<<5 | 1<<7 | 1<<3},
+	}
+
+	for _, c := range fields {
+		actual, _ := getField(c.expr, bounds{c.min, c.max, nil})
+		if actual != c.expected {
+			t.Errorf("%s => expected %d, got %d", c.expr, c.expected, actual)
+		}
+	}
+}
+
+func TestAll(t *testing.T) {
+	allBits := []struct {
+		r        bounds
+		expected uint64
+	}{
+		{minutes, 0xfffffffffffffff}, // 0-59: 60 ones
+		{hours, 0xffffff},            // 0-23: 24 ones
+		{dom, 0xfffffffe},            // 1-31: 31 ones, 1 zero
+		{months, 0x1ffe},             // 1-12: 12 ones, 1 zero
+		{dow, 0x7f},                  // 0-6: 7 ones
+	}
+
+	for _, c := range allBits {
+		actual := all(c.r) // all() adds the starBit, so compensate for that..
+		if c.expected|starBit != actual {
+			t.Errorf("%d-%d/%d => expected %b, got %b",
+				c.r.min, c.r.max, 1, c.expected|starBit, actual)
+		}
+	}
+}
+
+func TestBits(t *testing.T) {
+	bits := []struct {
+		min, max, step uint
+		expected       uint64
+	}{
+		{0, 0, 1, 0x1},
+		{1, 1, 1, 0x2},
+		{1, 5, 2, 0x2a}, // 101010
+		{1, 4, 2, 0xa},  // 1010
+	}
+
+	for _, c := range bits {
+		actual := getBits(c.min, c.max, c.step)
+		if c.expected != actual {
+			t.Errorf("%d-%d/%d => expected %b, got %b",
+				c.min, c.max, c.step, c.expected, actual)
+		}
+	}
+}
+
+func TestParse(t *testing.T) {
+	entries := []struct {
+		expr     string
+		expected Schedule
+		err      string
+	}{
+		{
+			expr: "* 5 * * * *",
+			expected: &SpecSchedule{
+				Second: all(seconds),
+				Minute: 1 << 5,
+				Hour:   all(hours),
+				Dom:    all(dom),
+				Month:  all(months),
+				Dow:    all(dow),
+			},
+		},
+		{
+			expr: "* 5 j * * *",
+			err:  "Failed to parse int from",
+		},
+		{
+			expr:     "@every 5m",
+			expected: ConstantDelaySchedule{Delay: time.Duration(5) * time.Minute},
+		},
+		{
+			expr: "@every Xm",
+			err:  "Failed to parse duration",
+		},
+		{
+			expr: "@yearly",
+			expected: &SpecSchedule{
+				Second: 1 << seconds.min,
+				Minute: 1 << minutes.min,
+				Hour:   1 << hours.min,
+				Dom:    1 << dom.min,
+				Month:  1 << months.min,
+				Dow:    all(dow),
+			},
+		},
+		{
+			expr: "@annually",
+			expected: &SpecSchedule{
+				Second: 1 << seconds.min,
+				Minute: 1 << minutes.min,
+				Hour:   1 << hours.min,
+				Dom:    1 << dom.min,
+				Month:  1 << months.min,
+				Dow:    all(dow),
+			},
+		},
+		{
+			expr: "@unrecognized",
+			err:  "Unrecognized descriptor",
+		},
+		{
+			expr: "* * * *",
+			err:  "Expected 5 to 6 fields",
+		},
+		{
+			expr: "",
+			err:  "Empty spec string",
+		},
+	}
+
+	for _, c := range entries {
+		actual, err := Parse(c.expr)
+		if len(c.err) != 0 && (err == nil || !strings.Contains(err.Error(), c.err)) {
+			t.Errorf("%s => expected %v, got %v", c.expr, c.err, err)
+		}
+		if len(c.err) == 0 && err != nil {
+			t.Errorf("%s => unexpected error %v", c.expr, err)
+		}
+		if !reflect.DeepEqual(actual, c.expected) {
+			t.Errorf("%s => expected %b, got %b", c.expr, c.expected, actual)
+		}
+	}
+}
+
+func TestStandardSpecSchedule(t *testing.T) {
+	entries := []struct {
+		expr     string
+		expected Schedule
+		err      string
+	}{
+		{
+			expr:     "5 * * * *",
+			expected: &SpecSchedule{1 << seconds.min, 1 << 5, all(hours), all(dom), all(months), all(dow)},
+		},
+		{
+			expr:     "@every 5m",
+			expected: ConstantDelaySchedule{time.Duration(5) * time.Minute},
+		},
+		{
+			expr: "5 j * * *",
+			err:  "Failed to parse int from",
+		},
+		{
+			expr: "* * * *",
+			err:  "Expected exactly 5 fields",
+		},
+	}
+
+	for _, c := range entries {
+		actual, err := ParseStandard(c.expr)
+		if len(c.err) != 0 && (err == nil || !strings.Contains(err.Error(), c.err)) {
+			t.Errorf("%s => expected %v, got %v", c.expr, c.err, err)
+		}
+		if len(c.err) == 0 && err != nil {
+			t.Errorf("%s => unexpected error %v", c.expr, err)
+		}
+		if !reflect.DeepEqual(actual, c.expected) {
+			t.Errorf("%s => expected %b, got %b", c.expr, c.expected, actual)
+		}
+	}
+}

common/src/github.com/robfig/cron/spec.go

@@ -0,0 +1,158 @@
+package cron
+
+import "time"
+
+// 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
+}
+
+// bounds provides a range of acceptable values (plus a map of name to value).
+type bounds struct {
+	min, max uint
+	names    map[string]uint
+}
+
+// The bounds for each field.
+var (
+	seconds = bounds{0, 59, nil}
+	minutes = bounds{0, 59, nil}
+	hours   = bounds{0, 23, nil}
+	dom     = bounds{1, 31, nil}
+	months  = bounds{1, 12, map[string]uint{
+		"jan": 1,
+		"feb": 2,
+		"mar": 3,
+		"apr": 4,
+		"may": 5,
+		"jun": 6,
+		"jul": 7,
+		"aug": 8,
+		"sep": 9,
+		"oct": 10,
+		"nov": 11,
+		"dec": 12,
+	}}
+	dow = bounds{0, 6, map[string]uint{
+		"sun": 0,
+		"mon": 1,
+		"tue": 2,
+		"wed": 3,
+		"thu": 4,
+		"fri": 5,
+		"sat": 6,
+	}}
+)
+
+const (
+	// Set the top bit if a star was included in the expression.
+	starBit = 1 << 63
+)
+
+// 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 {
+	// General approach:
+	// For Month, Day, Hour, Minute, Second:
+	// Check if the time value matches.  If yes, continue to the next field.
+	// If the field doesn't match the schedule, then increment the field until it matches.
+	// While incrementing the field, a wrap-around brings it back to the beginning
+	// of the field list (since it is necessary to re-verify previous field
+	// values)
+
+	// Start at the earliest possible time (the upcoming second).
+	t = t.Add(1*time.Second - time.Duration(t.Nanosecond())*time.Nanosecond)
+
+	// This flag indicates whether a field has been incremented.
+	added := false
+
+	// If no time is found within five years, return zero.
+	yearLimit := t.Year() + 5
+
+WRAP:
+	if t.Year() > yearLimit {
+		return time.Time{}
+	}
+
+	// Find the first applicable month.
+	// If it's this month, then do nothing.
+	for 1<<uint(t.Month())&s.Month == 0 {
+		// If we have to add a month, reset the other parts to 0.
+		if !added {
+			added = true
+			// Otherwise, set the date at the beginning (since the current time is irrelevant).
+			t = time.Date(t.Year(), t.Month(), 1, 0, 0, 0, 0, t.Location())
+		}
+		t = t.AddDate(0, 1, 0)
+
+		// Wrapped around.
+		if t.Month() == time.January {
+			goto WRAP
+		}
+	}
+
+	// Now get a day in that month.
+	for !dayMatches(s, t) {
+		if !added {
+			added = true
+			t = time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, t.Location())
+		}
+		t = t.AddDate(0, 0, 1)
+
+		if t.Day() == 1 {
+			goto WRAP
+		}
+	}
+
+	for 1<<uint(t.Hour())&s.Hour == 0 {
+		if !added {
+			added = true
+			t = time.Date(t.Year(), t.Month(), t.Day(), t.Hour(), 0, 0, 0, t.Location())
+		}
+		t = t.Add(1 * time.Hour)
+
+		if t.Hour() == 0 {
+			goto WRAP
+		}
+	}
+
+	for 1<<uint(t.Minute())&s.Minute == 0 {
+		if !added {
+			added = true
+			t = t.Truncate(time.Minute)
+		}
+		t = t.Add(1 * time.Minute)
+
+		if t.Minute() == 0 {
+			goto WRAP
+		}
+	}
+
+	for 1<<uint(t.Second())&s.Second == 0 {
+		if !added {
+			added = true
+			t = t.Truncate(time.Second)
+		}
+		t = t.Add(1 * time.Second)
+
+		if t.Second() == 0 {
+			goto WRAP
+		}
+	}
+
+	return t
+}
+
+// dayMatches returns true if the schedule's day-of-week and day-of-month
+// restrictions are satisfied by the given time.
+func dayMatches(s *SpecSchedule, t time.Time) bool {
+	var (
+		domMatch bool = 1<<uint(t.Day())&s.Dom > 0
+		dowMatch bool = 1<<uint(t.Weekday())&s.Dow > 0
+	)
+	if s.Dom&starBit > 0 || s.Dow&starBit > 0 {
+		return domMatch && dowMatch
+	}
+	return domMatch || dowMatch
+}

common/src/github.com/robfig/cron/spec_test.go

@@ -0,0 +1,249 @@
+package cron
+
+import (
+	"testing"
+	"time"
+)
+
+func TestActivation(t *testing.T) {
+	tests := []struct {
+		time, spec string
+		expected   bool
+	}{
+		// Every fifteen minutes.
+		{"Mon Jul 9 15:00 2012", "0 0/15 * * *", true},
+		{"Mon Jul 9 15:45 2012", "0 0/15 * * *", true},
+		{"Mon Jul 9 15:40 2012", "0 0/15 * * *", false},
+
+		// Every fifteen minutes, starting at 5 minutes.
+		{"Mon Jul 9 15:05 2012", "0 5/15 * * *", true},
+		{"Mon Jul 9 15:20 2012", "0 5/15 * * *", true},
+		{"Mon Jul 9 15:50 2012", "0 5/15 * * *", true},
+
+		// Named months
+		{"Sun Jul 15 15:00 2012", "0 0/15 * * Jul", true},
+		{"Sun Jul 15 15:00 2012", "0 0/15 * * Jun", false},
+
+		// Everything set.
+		{"Sun Jul 15 08:30 2012", "0 30 08 ? Jul Sun", true},
+		{"Sun Jul 15 08:30 2012", "0 30 08 15 Jul ?", true},
+		{"Mon Jul 16 08:30 2012", "0 30 08 ? Jul Sun", false},
+		{"Mon Jul 16 08:30 2012", "0 30 08 15 Jul ?", false},
+
+		// Predefined schedules
+		{"Mon Jul 9 15:00 2012", "@hourly", true},
+		{"Mon Jul 9 15:04 2012", "@hourly", false},
+		{"Mon Jul 9 15:00 2012", "@daily", false},
+		{"Mon Jul 9 00:00 2012", "@daily", true},
+		{"Mon Jul 9 00:00 2012", "@weekly", false},
+		{"Sun Jul 8 00:00 2012", "@weekly", true},
+		{"Sun Jul 8 01:00 2012", "@weekly", false},
+		{"Sun Jul 8 00:00 2012", "@monthly", false},
+		{"Sun Jul 1 00:00 2012", "@monthly", true},
+
+		// Test interaction of DOW and DOM.
+		// If both are specified, then only one needs to match.
+		{"Sun Jul 15 00:00 2012", "0 * * 1,15 * Sun", true},
+		{"Fri Jun 15 00:00 2012", "0 * * 1,15 * Sun", true},
+		{"Wed Aug 1 00:00 2012", "0 * * 1,15 * Sun", true},
+
+		// However, if one has a star, then both need to match.
+		{"Sun Jul 15 00:00 2012", "0 * * * * Mon", false},
+		{"Sun Jul 15 00:00 2012", "0 * * */10 * Sun", false},
+		{"Mon Jul 9 00:00 2012", "0 * * 1,15 * *", false},
+		{"Sun Jul 15 00:00 2012", "0 * * 1,15 * *", true},
+		{"Sun Jul 15 00:00 2012", "0 * * */2 * Sun", true},
+	}
+
+	for _, test := range tests {
+		sched, err := Parse(test.spec)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+		actual := sched.Next(getTime(test.time).Add(-1 * time.Second))
+		expected := getTime(test.time)
+		if test.expected && expected != actual || !test.expected && expected == actual {
+			t.Errorf("Fail evaluating %s on %s: (expected) %s != %s (actual)",
+				test.spec, test.time, expected, actual)
+		}
+	}
+}
+
+func TestNext(t *testing.T) {
+	runs := []struct {
+		time, spec string
+		expected   string
+	}{
+		// Simple cases
+		{"Mon Jul 9 14:45 2012", "0 0/15 * * *", "Mon Jul 9 15:00 2012"},
+		{"Mon Jul 9 14:59 2012", "0 0/15 * * *", "Mon Jul 9 15:00 2012"},
+		{"Mon Jul 9 14:59:59 2012", "0 0/15 * * *", "Mon Jul 9 15:00 2012"},
+
+		// Wrap around hours
+		{"Mon Jul 9 15:45 2012", "0 20-35/15 * * *", "Mon Jul 9 16:20 2012"},
+
+		// Wrap around days
+		{"Mon Jul 9 23:46 2012", "0 */15 * * *", "Tue Jul 10 00:00 2012"},
+		{"Mon Jul 9 23:45 2012", "0 20-35/15 * * *", "Tue Jul 10 00:20 2012"},
+		{"Mon Jul 9 23:35:51 2012", "15/35 20-35/15 * * *", "Tue Jul 10 00:20:15 2012"},
+		{"Mon Jul 9 23:35:51 2012", "15/35 20-35/15 1/2 * *", "Tue Jul 10 01:20:15 2012"},
+		{"Mon Jul 9 23:35:51 2012", "15/35 20-35/15 10-12 * *", "Tue Jul 10 10:20:15 2012"},
+
+		{"Mon Jul 9 23:35:51 2012", "15/35 20-35/15 1/2 */2 * *", "Thu Jul 11 01:20:15 2012"},
+		{"Mon Jul 9 23:35:51 2012", "15/35 20-35/15 * 9-20 * *", "Wed Jul 10 00:20:15 2012"},
+		{"Mon Jul 9 23:35:51 2012", "15/35 20-35/15 * 9-20 Jul *", "Wed Jul 10 00:20:15 2012"},
+
+		// Wrap around months
+		{"Mon Jul 9 23:35 2012", "0 0 0 9 Apr-Oct ?", "Thu Aug 9 00:00 2012"},
+		{"Mon Jul 9 23:35 2012", "0 0 0 */5 Apr,Aug,Oct Mon", "Mon Aug 6 00:00 2012"},
+		{"Mon Jul 9 23:35 2012", "0 0 0 */5 Oct Mon", "Mon Oct 1 00:00 2012"},
+
+		// Wrap around years
+		{"Mon Jul 9 23:35 2012", "0 0 0 * Feb Mon", "Mon Feb 4 00:00 2013"},
+		{"Mon Jul 9 23:35 2012", "0 0 0 * Feb Mon/2", "Fri Feb 1 00:00 2013"},
+
+		// Wrap around minute, hour, day, month, and year
+		{"Mon Dec 31 23:59:45 2012", "0 * * * * *", "Tue Jan 1 00:00:00 2013"},
+
+		// Leap year
+		{"Mon Jul 9 23:35 2012", "0 0 0 29 Feb ?", "Mon Feb 29 00:00 2016"},
+
+		// Daylight savings time 2am EST (-5) -> 3am EDT (-4)
+		{"2012-03-11T00:00:00-0500", "0 30 2 11 Mar ?", "2013-03-11T02:30:00-0400"},
+
+		// hourly job
+		{"2012-03-11T00:00:00-0500", "0 0 * * * ?", "2012-03-11T01:00:00-0500"},
+		{"2012-03-11T01:00:00-0500", "0 0 * * * ?", "2012-03-11T03:00:00-0400"},
+		{"2012-03-11T03:00:00-0400", "0 0 * * * ?", "2012-03-11T04:00:00-0400"},
+		{"2012-03-11T04:00:00-0400", "0 0 * * * ?", "2012-03-11T05:00:00-0400"},
+
+		// 1am nightly job
+		{"2012-03-11T00:00:00-0500", "0 0 1 * * ?", "2012-03-11T01:00:00-0500"},
+		{"2012-03-11T01:00:00-0500", "0 0 1 * * ?", "2012-03-12T01:00:00-0400"},
+
+		// 2am nightly job (skipped)
+		{"2012-03-11T00:00:00-0500", "0 0 2 * * ?", "2012-03-12T02:00:00-0400"},
+
+		// Daylight savings time 2am EDT (-4) => 1am EST (-5)
+		{"2012-11-04T00:00:00-0400", "0 30 2 04 Nov ?", "2012-11-04T02:30:00-0500"},
+		{"2012-11-04T01:45:00-0400", "0 30 1 04 Nov ?", "2012-11-04T01:30:00-0500"},
+
+		// hourly job
+		{"2012-11-04T00:00:00-0400", "0 0 * * * ?", "2012-11-04T01:00:00-0400"},
+		{"2012-11-04T01:00:00-0400", "0 0 * * * ?", "2012-11-04T01:00:00-0500"},
+		{"2012-11-04T01:00:00-0500", "0 0 * * * ?", "2012-11-04T02:00:00-0500"},
+
+		// 1am nightly job (runs twice)
+		{"2012-11-04T00:00:00-0400", "0 0 1 * * ?", "2012-11-04T01:00:00-0400"},
+		{"2012-11-04T01:00:00-0400", "0 0 1 * * ?", "2012-11-04T01:00:00-0500"},
+		{"2012-11-04T01:00:00-0500", "0 0 1 * * ?", "2012-11-05T01:00:00-0500"},
+
+		// 2am nightly job
+		{"2012-11-04T00:00:00-0400", "0 0 2 * * ?", "2012-11-04T02:00:00-0500"},
+		{"2012-11-04T02:00:00-0500", "0 0 2 * * ?", "2012-11-05T02:00:00-0500"},
+
+		// 3am nightly job
+		{"2012-11-04T00:00:00-0400", "0 0 3 * * ?", "2012-11-04T03:00:00-0500"},
+		{"2012-11-04T03:00:00-0500", "0 0 3 * * ?", "2012-11-05T03:00:00-0500"},
+
+		// Unsatisfiable
+		{"Mon Jul 9 23:35 2012", "0 0 0 30 Feb ?", ""},
+		{"Mon Jul 9 23:35 2012", "0 0 0 31 Apr ?", ""},
+	}
+
+	for _, c := range runs {
+		sched, err := Parse(c.spec)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+		actual := sched.Next(getTime(c.time))
+		expected := getTime(c.expected)
+		if !actual.Equal(expected) {
+			t.Errorf("%s, \"%s\": (expected) %v != %v (actual)", c.time, c.spec, expected, actual)
+		}
+	}
+}
+
+func TestErrors(t *testing.T) {
+	invalidSpecs := []string{
+		"xyz",
+		"60 0 * * *",
+		"0 60 * * *",
+		"0 0 * * XYZ",
+	}
+	for _, spec := range invalidSpecs {
+		_, err := Parse(spec)
+		if err == nil {
+			t.Error("expected an error parsing: ", spec)
+		}
+	}
+}
+
+func getTime(value string) time.Time {
+	if value == "" {
+		return time.Time{}
+	}
+	t, err := time.Parse("Mon Jan 2 15:04 2006", value)
+	if err != nil {
+		t, err = time.Parse("Mon Jan 2 15:04:05 2006", value)
+		if err != nil {
+			t, err = time.Parse("2006-01-02T15:04:05-0700", value)
+			if err != nil {
+				panic(err)
+			}
+			// Daylight savings time tests require location
+			if ny, err := time.LoadLocation("America/New_York"); err == nil {
+				t = t.In(ny)
+			}
+		}
+	}
+
+	return t
+}
+
+func TestNextWithTz(t *testing.T) {
+	runs := []struct {
+		time, spec string
+		expected   string
+	}{
+		// Failing tests
+		{"2016-01-03T13:09:03+0530", "0 14 14 * * *", "2016-01-03T14:14:00+0530"},
+		{"2016-01-03T04:09:03+0530", "0 14 14 * * ?", "2016-01-03T14:14:00+0530"},
+
+		// Passing tests
+		{"2016-01-03T14:09:03+0530", "0 14 14 * * *", "2016-01-03T14:14:00+0530"},
+		{"2016-01-03T14:00:00+0530", "0 14 14 * * ?", "2016-01-03T14:14:00+0530"},
+	}
+	for _, c := range runs {
+		sched, err := Parse(c.spec)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+		actual := sched.Next(getTimeTZ(c.time))
+		expected := getTimeTZ(c.expected)
+		if !actual.Equal(expected) {
+			t.Errorf("%s, \"%s\": (expected) %v != %v (actual)", c.time, c.spec, expected, actual)
+		}
+	}
+}
+
+func getTimeTZ(value string) time.Time {
+	if value == "" {
+		return time.Time{}
+	}
+	t, err := time.Parse("Mon Jan 2 15:04 2006", value)
+	if err != nil {
+		t, err = time.Parse("Mon Jan 2 15:04:05 2006", value)
+		if err != nil {
+			t, err = time.Parse("2006-01-02T15:04:05-0700", value)
+			if err != nil {
+				panic(err)
+			}
+		}
+	}
+
+	return t
+}