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https://github.com/fthomas/fs2-cron
FS2 streams based on cron expressions
https://github.com/fthomas/fs2-cron
cron cron4s fs2 functional-programming scala
Last synced: 20 days ago
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FS2 streams based on cron expressions
- Host: GitHub
- URL: https://github.com/fthomas/fs2-cron
- Owner: fthomas
- License: apache-2.0
- Created: 2018-08-24T16:48:32.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2024-11-05T17:48:12.000Z (about 1 month ago)
- Last Synced: 2024-11-15T21:05:11.398Z (28 days ago)
- Topics: cron, cron4s, fs2, functional-programming, scala
- Language: Scala
- Homepage:
- Size: 886 KB
- Stars: 134
- Watchers: 7
- Forks: 17
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-ccamel - fthomas/fs2-cron - FS2 streams based on cron expressions (Scala)
README
# fs2-cron
[](https://github.com/fthomas/fs2-cron/actions/workflows/ci.yml)
[](https://codecov.io/gh/fthomas/fs2-cron)
[](https://gitter.im/fthomas/fs2-cron?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
[](https://index.scala-lang.org/fthomas/fs2-cron/fs2-cron-core)
[](https://javadoc.io/doc/eu.timepit/fs2-cron-core_2.12)
**fs2-cron** is a microlibrary that provides [FS2][FS2] streams based
on [Cron4s][Cron4s] cron expressions or [Calev][Calev] calendar
events.
It is provided for Scala 2.12, 2.13 and `fs2-cron-calev` also for
Scala 3.
## Examples
```scala
import cats.effect.IO
import cats.effect.unsafe.implicits.global
import fs2.Stream
import java.time.LocalTime
val printTime = Stream.eval(IO(println(LocalTime.now)))
```
### Using Cron4s library
Requires the `fs2-cron-cron4s` module:
```scala
import cron4s.Cron
import eu.timepit.fs2cron.cron4s.Cron4sScheduler
val cronScheduler = Cron4sScheduler.systemDefault[IO]
// cronScheduler: eu.timepit.fs2cron.Scheduler[IO, cron4s.expr.CronExpr] = eu.timepit.fs2cron.cron4s.Cron4sScheduler$$anon$1@3b612fa5
val evenSeconds = Cron.unsafeParse("*/2 * * ? * *")
// evenSeconds: cron4s.package.CronExpr = CronExpr(
// seconds = */2,
// minutes = *,
// hours = *,
// daysOfMonth = ?,
// months = *,
// daysOfWeek = *
// )
val scheduled = cronScheduler.awakeEvery(evenSeconds) >> printTime
// scheduled: Stream[[x]IO[x], Unit] = Stream(..)
scheduled.take(3).compile.drain.unsafeRunSync()
// 22:34:46.145109392
// 22:34:48.001058522
// 22:34:50.001971813
```
```scala
val everyFiveSeconds = Cron.unsafeParse("*/5 * * ? * *")
// everyFiveSeconds: cron4s.package.CronExpr = CronExpr(
// seconds = */5,
// minutes = *,
// hours = *,
// daysOfMonth = ?,
// months = *,
// daysOfWeek = *
// )
val scheduledTasks = cronScheduler.schedule(List(
evenSeconds -> Stream.eval(IO(println(LocalTime.now.toString + " task 1"))),
everyFiveSeconds -> Stream.eval(IO(println(LocalTime.now.toString + " task 2")))
))
// scheduledTasks: Stream[IO, Unit] = Stream(..)
scheduledTasks.take(9).compile.drain.unsafeRunSync()
// 22:34:52.001721651 task 1
// 22:34:54.001702294 task 1
// 22:34:55.002032079 task 2
// 22:34:56.000919733 task 1
// 22:34:58.000939089 task 1
// 22:35:00.001158852 task 1
// 22:35:00.001743567 task 2
// 22:35:02.001037743 task 1
// 22:35:04.001006980 task 1
```
#### Cancelling the scheduled task
Using `Stream#interruptWhen(haltWhenTrue)`
```scala
import cats.effect._
import cron4s.Cron
import eu.timepit.fs2cron.cron4s.Cron4sScheduler
import fs2.Stream
import fs2.concurrent.SignallingRef
import java.time.LocalTime
import scala.concurrent.duration._
object TestApp extends IOApp.Simple {
val printTime = Stream.eval(IO(println(LocalTime.now)))
override def run: IO[Unit] = {
val cronScheduler = Cron4sScheduler.systemDefault[IO]
val evenSeconds = Cron.unsafeParse("*/2 * * ? * *")
val scheduled = cronScheduler.awakeEvery(evenSeconds) >> printTime
val cancel = SignallingRef[IO, Boolean](false)
for {
c <- cancel
s <- scheduled.interruptWhen(c).repeat.compile.drain.start
//prints about 5 times before stop
_ <- Temporal[IO].sleep(10.seconds) >> c.set(true)
} yield s
}
}
```
### Using Calev library
Requires the `fs2-cron-calev` module:
```scala
import com.github.eikek.calev.CalEvent
import eu.timepit.fs2cron.calev.CalevScheduler
val calevScheduler = CalevScheduler.systemDefault[IO]
// calevScheduler: eu.timepit.fs2cron.Scheduler[IO, CalEvent] = eu.timepit.fs2cron.calev.CalevScheduler$$anon$1@5b72ab85
val oddSeconds = CalEvent.unsafe("*-*-* *:*:1/2")
// oddSeconds: CalEvent = CalEvent(
// weekday = All,
// date = DateEvent(year = All, month = All, day = All),
// time = TimeEvent(
// hour = All,
// minute = All,
// seconds = List(values = Vector(Single(value = 1, rep = Some(value = 2))))
// ),
// zone = None
// )
val calevScheduled = calevScheduler.awakeEvery(oddSeconds) >> printTime
// calevScheduled: Stream[[x]IO[x], Unit] = Stream(..)
calevScheduled.take(3).compile.drain.unsafeRunSync()
// 22:35:05.005121709
// 22:35:07.000442205
// 22:35:09.000989961
```
```scala
val everyFourSeconds = CalEvent.unsafe("*-*-* *:*:0/4")
// everyFourSeconds: CalEvent = CalEvent(
// weekday = All,
// date = DateEvent(year = All, month = All, day = All),
// time = TimeEvent(
// hour = All,
// minute = All,
// seconds = List(values = Vector(Single(value = 0, rep = Some(value = 4))))
// ),
// zone = None
// )
val calevScheduledTasks = calevScheduler.schedule(List(
oddSeconds -> Stream.eval(IO(println(LocalTime.now.toString + " task 1"))),
everyFourSeconds -> Stream.eval(IO(println(LocalTime.now.toString + " task 2")))
))
// calevScheduledTasks: Stream[IO, Unit] = Stream(..)
calevScheduledTasks.take(9).compile.drain.unsafeRunSync()
// 22:35:11.000475346 task 1
// 22:35:12.000865309 task 2
// 22:35:13.000723319 task 1
// 22:35:15.001042916 task 1
// 22:35:16.000423061 task 2
// 22:35:17.000806045 task 1
// 22:35:19.000158236 task 1
// 22:35:20.000879932 task 2
// 22:35:21.000786710 task 1
```
## Using fs2-cron
The latest version of the library is available for Scala 2.12 and 2.13.
If you're using sbt, add the following to your build:
```sbt
libraryDependencies ++= Seq(
"eu.timepit" %% "fs2-cron-cron4s" % "0.9.0" //and/or
"eu.timepit" %% "fs2-cron-calev" % "0.9.0"
)
```
## License
**fs2-cron** is licensed under the Apache License, Version 2.0, available at
http://www.apache.org/licenses/LICENSE-2.0 and also in the
[LICENSE](https://github.com/fthomas/status-page/blob/master/LICENSE) file.
[Cron4s]: https://github.com/alonsodomin/cron4s
[FS2]: https://github.com/functional-streams-for-scala/fs2
[Calev]: https://github.com/eikek/calev