From b9b0e43854bb4b4530838ee96685ba7ba3cea09b Mon Sep 17 00:00:00 2001
From: Victor Castell <victor@victorcastell.com>
Date: Thu, 2 Jun 2016 23:15:20 +0200
Subject: [PATCH] One off jobs (#137)

One off jobs
---
 .travis.yml         |  6 +-----
 cron/doc.go         | 13 +++++++++++++
 cron/parser.go      |  9 +++++++++
 cron/parser_test.go |  2 ++
 cron/simple.go      | 21 +++++++++++++++++++++
 scripts/test.sh     |  2 +-
 6 files changed, 47 insertions(+), 6 deletions(-)
 create mode 100644 cron/simple.go

diff --git a/.travis.yml b/.travis.yml
index 56f0189dd..eab6e8dcd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -23,8 +23,4 @@ script:
   - go vet ./...
   # - fgt golint ./...
   - glide install
-  - go test -v ./dkron
-
-env:
-  global:
-    - GO15VENDOREXPERIMENT=1
+  - go test -v $(glide novendor)
diff --git a/cron/doc.go b/cron/doc.go
index be39098ce..5aba99cdc 100644
--- a/cron/doc.go
+++ b/cron/doc.go
@@ -100,6 +100,19 @@ 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.
 
+Fixed times
+
+You may also schedule a job to execute once and never more. This is supported by
+formatting the cron spec like this:
+
+    @at <datetime>
+
+Where "datetime" is a string accepted by time.Parse in RFC 3339/ISO 8601 format
+(https://golang.org/pkg/time/#Parse).
+
+For example, "@at 2018-01-02T15:04:00" would run the job on the specified date and time
+assuming UTC timezone.
+
 Time zones
 
 All interpretation and scheduling is done in the machine's local time zone (as
diff --git a/cron/parser.go b/cron/parser.go
index fd04dca82..e4342d306 100644
--- a/cron/parser.go
+++ b/cron/parser.go
@@ -236,6 +236,15 @@ func parseDescriptor(spec string) Schedule {
 		return Every(duration)
 	}
 
+	const at = "@at "
+	if strings.HasPrefix(spec, at) {
+		date, err := time.Parse(time.RFC3339, spec[len(at):])
+		if err != nil {
+			log.Panicf("Failed to parse date %s: %s", spec, err)
+		}
+		return At(date)
+	}
+
 	log.Panicf("Unrecognized descriptor: %s", spec)
 	return nil
 }
diff --git a/cron/parser_test.go b/cron/parser_test.go
index f03299e5e..db76cb2e1 100644
--- a/cron/parser_test.go
+++ b/cron/parser_test.go
@@ -103,6 +103,8 @@ func TestSpecSchedule(t *testing.T) {
 	}{
 		{"* 5 * * * *", &SpecSchedule{all(seconds), 1 << 5, all(hours), all(dom), all(months), all(dow)}},
 		{"@every 5m", ConstantDelaySchedule{time.Duration(5) * time.Minute}},
+		{"@at 2018-01-02T15:04:00Z", SimpleSchedule{time.Date(2018, time.January, 2, 15, 4, 0, 0, time.UTC)}},
+		{"@at 2019-02-04T09:20:00+06:00", SimpleSchedule{time.Date(2019, time.February, 4, 9, 20, 0, 0, time.FixedZone("", 21600))}},
 	}
 
 	for _, c := range entries {
diff --git a/cron/simple.go b/cron/simple.go
new file mode 100644
index 000000000..445374bde
--- /dev/null
+++ b/cron/simple.go
@@ -0,0 +1,21 @@
+package cron
+
+import "time"
+
+// SimpleDelaySchedule represents a simple non recurring duration.
+type SimpleSchedule struct {
+	Date time.Time
+}
+
+// Just store the given time for this schedule.
+func At(date time.Time) SimpleSchedule {
+	return SimpleSchedule{
+		Date: date,
+	}
+}
+
+// Next conforms to the Schedule interface but this kind of jobs
+// doesn't need to be run more than once, so it doesn't return a new date but the existing one.
+func (schedule SimpleSchedule) Next(t time.Time) time.Time {
+	return schedule.Date
+}
diff --git a/scripts/test.sh b/scripts/test.sh
index 43f3a706c..ee99e210c 100755
--- a/scripts/test.sh
+++ b/scripts/test.sh
@@ -3,4 +3,4 @@
 docker-compose up -d etcd
 export COMPOSE_ETCD_PORT=`docker port dkron_etcd_1 4001/tcp | cut -d":" -f 2`
 export DKRON_BACKEND_MACHINE=`docker-machine ip default`:$COMPOSE_ETCD_PORT
-go test -v ./dkron $1
+go test -v $(glide novendor) $1