can I combine kotlinx.coroutines.sync.Semaphore.ac...

# coroutines

[rrva]

can I combine kotlinx.coroutines.sync.Semaphore.acquire and kotlinx.coroutines.withTimeout ?

import kotlinx.coroutines.sync.Semaphore
import kotlinx.coroutines.withTimeout

private val concurrentRequests = Semaphore(50)

suspend fun foo() {
    withTimeout(10) {
        concurrentRequests.acquire()
    }
    try {
        doStuff()
    } finally {
        concurrentRequests.release()
    }
}

[octylFractal]

what do you mean by that? haven't you already done so here?

[rrva]

I guess my question was: “kotlinx.coroutines.sync.Semaphore.acquire suspends until a permit is available. Is wrapping that inside withTimeout a valid way of waiting until a permit is available or the timeout is reached, whichever comes first, or is that code racy in some way in the sense that it is possible to acquire a permit AND receive a timeout in the same coroutine?”

[octylFractal]

I do not believe so, either acquire() does not see cancellation and successfully returns (and in that case withTimeout will not throw); OR acquire() sees the cancellation from timeout and will not acquire the semaphore

[octylFractal]

of note is this internal comment:

* If timeout is exceeded, but withTimeout() block was not suspended, we would like to return block value,
     * not a timeout exception.

[louiscad]

You can combine them that way, yes.

[rrva]

thanks