Add seconds, N/step handling, named months/dows, checking activation …

…at a time, a bunch of cron spec tests.

cron.go

@@ -1,5 +1,86 @@
+// This library implements a cron spec parser and runner.  See the README for
+// more details.
 package cron
 
+import (
+	"time"
+)
+
+// Cron keeps track of any number of entries, invoking the associated func as
+// specified by the spec.  See http://en.wikipedia.org/wiki/Cron
+// It may be started and stopped.
 type Cron struct {
 	Entries []*Entry
+	stop    chan struct{}
+}
+
+// A cron entry consists of a schedule and the func to execute on that schedule.
+type Entry struct {
+	*Schedule
+	Func func()
+}
+
+func New() *Cron {
+	return new(Cron)
+}
+
+func (c *Cron) Add(spec string, cmd func()) {
+	c.Entries = append(c.Entries, &Entry{Parse(spec), cmd})
+}
+
+func (c *Cron) Run() {
+	ticker := time.Tick(1 * time.Minute)
+	for {
+		select {
+		case now := <-ticker:
+			for _, entry := range c.Entries {
+				if matches(now, entry.Schedule) {
+					go entry.Func()
+				}
+			}
+
+		case <-c.stop:
+			return
+		}
+	}
 }
+
+func (c Cron) Stop() {
+	c.stop <- struct{}{}
+}
+
+// Return true if the given entries overlap.
+func matches(t time.Time, sched *Schedule) bool {
+	var (
+		domMatch bool = 1<<uint(t.Day())&sched.Dom > 0
+		dowMatch bool = 1<<uint(t.Weekday())&sched.Dow > 0
+		dayMatch bool
+	)
+
+	if sched.Dom&STAR_BIT > 0 || sched.Dow&STAR_BIT > 0 {
+		dayMatch = domMatch && dowMatch
+	} else {
+		dayMatch = domMatch || dowMatch
+	}
+
+	return 1<<uint(t.Minute())&sched.Minute > 0 &&
+		1<<uint(t.Hour())&sched.Hour > 0 &&
+		1<<uint(t.Month())&sched.Month > 0 &&
+		dayMatch
+}
+
+// // Return the number of units betwee now and then.
+// func difference(then, now uint64, r bounds) uint {
+// 	// Shift the current time fields left (and around) until & is non-zero.
+// 	i := 0
+// 	for then & now << ((i - r.min) % (r.max - r.min + 1) + r.min) == 0 {
+// 		// A guard against no units selected.
+// 		if i > r.max {
+// 			panic("Entry had no minute/hour selected.")
+// 		}
+
+// 		i++
+// 	}
+
+// 	return i
+// }

cron_test.go

@@ -0,0 +1,73 @@
+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},
+	}
+
+	for _, test := range tests {
+		actual := matches(getTime(test.time), Parse(test.spec))
+		if test.expected != actual {
+			t.Logf("Actual Minutes mask: %b", Parse(test.spec).Minute)
+			t.Errorf("Fail evaluating %s on %s: (expected) %t != %t (actual)",
+				test.spec, test.time, test.expected, actual)
+		}
+	}
+}
+
+func getTime(value string) time.Time {
+	t, err := time.Parse("Mon Jan 2 15:04 2006", value)
+	if err != nil {
+		panic(err)
+	}
+	return t
+}