@DCameronMauch You can use a cats.effect.concurrent.Ref[F, Boolean] (or a cats.effect.concurrent.Deferred[F, Boolean] but this might be more complex, less so with TryableDeferred) as a signal of sorts to check at certain points in your code. For Refor TryableDeferred that would involve checking it at various points in your code.
FWIW a lot of this use case is handled by libraries such as FS2, with Stream.resource handling the "cleanly" part of cancellation (closing resources, etc) and .interruptWhen(signal) cancelling your stream.
a background process which however gets cleanly cancelled on termination
no other machinery needed
er
yay gitter for not updating
@DCameronMauch We use it in production for "do work from rabbit queue" and it works just fine
didn’t realize there was already something out there for my use case
but I'm 99% sure it solves it for you
fs2 is a good base for when you want
- to do some kind of work on elements or batches of elements
- you want some kind of pub/sub interaction, queues etc
- you want to encode more complex concurrency behaviors than
IOmakes easy - you have a lot of
IObehaviors and you want to compose them more orthogonally thanIOmakes easy
The c-e ecosystem is pretty broad at this point; I highly recommend googling "$task cats-effect" or "$task fs2" when you need a tool. Chances are you'll find something, or at least confirm that you need to do it yourself
What can I be doing wrong to get an
[error] ... Symbol 'type cats.Parallel.Aux' is missing from the classpath.
[error] This symbol is required by 'method cats.effect.IOInstances.ioParallel' on implicit val ec = implicitly[ExecutionContext]
implicit val cs: ContextShift[IO] = IO.contextShift(ec)
val sync = implicitly[Sync[IO]]
I see cats-effects 1.5.0 is evicted by 2.0.0 in the project, but in this code excerpt it is the same
IO, isn't it?
cats-effect should be binary compatible between 1.5 and 2.0, and cats itself should be as well, so the evictions shouldn't matter, but that's exactly at it looks like is happening
@kolov can you tell me what your cats-effect, cats, and circe versions are? circe 0.9 I take it?
so if cats-effect is pushed forward to 2.0.0, then cats must be as well
cats-effect would not be compatible at all with cats-core 1.x
After I posted this I noticed that in another class with different
extends in the same project very similar code compiles without problems. I'll look further tomorrow.
@kolov: If we can figure out what depends on circe-core 0.11.0, that'll help.
@kolov: I recommend the sbt-dependency-graph plugin.
If I have an IO with a timeout:
IO(somefn).timeout(100 millis)Is it possible for somefn to create an IO which doesnt get timed out?
def somefn = {
readDb >> computeSomething >> fireOffaTask >> updateDb
}I'm trying to have the fireOffaTask run without being effected by timeout.
Not sure what you're trying to achieve exactly
Do you care about error handling in that task you want to run in the background?
im trying to implement a fire and forgot. That won't get a timeout exception.
also
ioa.start.void will still get timeout exception.
If you don't want that, then you'd need to do things differently