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Merged
merged 1 commit into from
May 29, 2018
Merged

Do not forcibly exit on ExitCode.Success #252

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2 changes: 2 additions & 0 deletions core/js/src/main/scala/cats/effect/internals/IOAppPlatform.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,8 @@ private[effect] object IOAppPlatform {
case Left(t) =>
IO(Logger.reportFailure(t)) *>
IO(sys.exit(ExitCode.Error.code))
case Right(0) =>
IO.unit
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JS is always tricky. I guess at this point the keep-alive was canceled.

But yes, this is better for JS as well.

case Right(code) =>
IO(sys.exit(code))
}.unsafeRunSync()
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9 changes: 8 additions & 1 deletion core/jvm/src/main/scala/cats/effect/internals/IOAppPlatform.scala
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Expand Up @@ -26,7 +26,14 @@ private[effect] object IOAppPlatform {
val code = mainFiber(args, timer)(run).flatMap(_.join)
.handleErrorWith(t => IO(Logger.reportFailure(t)) *> IO(ExitCode.Error.code))
.unsafeRunSync()
sys.exit(code)

if (code === 0) {
// Return naturally from main. This allows any non-daemon
// threads to gracefully complete their work, and managed
// environments to execute their own shutdown hooks.
()
}
else sys.exit(code)
}

def mainFiber(args: Array[String], timer: Eval[Timer[IO]])(run: List[String] => IO[ExitCode]): IO[Fiber[IO, Int]] = {
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18 changes: 13 additions & 5 deletions core/shared/src/main/scala/cats/effect/IOApp.scala
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Expand Up @@ -20,13 +20,21 @@ package effect
import cats.effect.internals.IOAppPlatform

/**
* `App` type that runs a [[cats.effect.IO]] and exits with the
* returned code. If the `IO` raises an error, then the stack trace
* is printed to standard error and the JVM exits with code 1.
* `App` type that runs a [[cats.effect.IO]]. Shutdown occurs after
* the `IO` completes, as follows:
*
* - If completed with `ExitCode.Success`, the main method exits and
* shutdown is handled by the platform.
*
* - If completed with any other [[ExitCode]], `sys.exit` is called
* with the specified code.
*
* - If the `IO` raises an error, the stack trace is printed to
* standard error and `sys.exit(1)` is called.
*
* When a shutdown is requested via a signal, the `IO` is canceled and
* we wait for the `IO` to release any resources. The JVM exits with
* the numeric value of the signal plus 128.
* we wait for the `IO` to release any resources. The process exits
* with the numeric value of the signal plus 128.
*
* {{{
* import cats.effect.IO
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