If I have a ```Channel<Unit>(capacity = Channel.UNLIMITED)``` and I never close it, is it guar...

# coroutines

[David Glasser]

If I have a

Channel<Unit>(capacity = Channel.UNLIMITED)

and I never close it, is it guaranteed that offer will always succeed?

[zak.taccardi]

yes, until you hit a memory issue

[zak.taccardi]

or if the scope is cancelled

[zak.taccardi]

oops, channels don’t have a scope haha

[David Glasser]

and specifically, if I call receive() at most once, I should be in good shape?

[David Glasser]

(basically just trying to make a latch where one coroutine can wait on it, and various other places (which aren't all coroutines) can allow it to continue)

[zak.taccardi]

receive like in a while loop?

[David Glasser]

nah, just once

[zak.taccardi]

why not use a deferred then?

[David Glasser]

just like a one-time synchronization primitive, "wait until some other coro lets me continue"

[David Glasser]

well, it's fulfillable by multiple other places

[David Glasser]

this is like "let the main loop finish if any of these various places tell us the program should be over", that sort of thing

[zak.taccardi]

CompletableDeferred<Unit>() should be effectively the same thing but with the guarantee it can only emit once

[David Glasser]

with .complete(Unit) and .await()?

[zak.taccardi]

yeah

[David Glasser]

and i can just do parent = null happily?

[zak.taccardi]

not sure what you mean by parent

[David Glasser]

initialize it with CompletableDeferred<Unit>(parent = null) rather than somethign else. this is all kinda at top program level

[zak.taccardi]

even if you are top level, you still have a top level scope

[David Glasser]

so i'm ok with no cancellation happening (in fact, i would rather not think about this Deferred being cancellable)

[zak.taccardi]

oh yeah, parent is null by default - that’s fine

[zak.taccardi]

since you are synchronizing between 2 coroutines