eventfd

8.12

eventfd🔗ℹ

Linux eventfd interface for Racket.

package: eventfd

Interface that allows manipulation of Linux eventfd descriptors in a way similar to Racket’s semaphores.

procedure
(eventfd? value) → boolean?
value : any/c

Predicate identifying an event descriptor structure. These event descriptors also act as a synchronizable event that produces same results as eventfd-wait would.

procedure
(eventfd initial-value
[ #:semaphore? semaphore?]) → eventfd?
initial-value : exact-nonnegative-integer?
semaphore? : boolean? = #f

Create completely new event descriptor. Remember that these count towards process file descriptor count.

procedure
(fd->eventfd fd) → eventfd?
fd : exact-nonnegative-integer?

Create an eventfd? structure for an existing descriptor. It is undefined what happens when you pass it something that is not a valid event descriptor.

procedure
(eventfd-post efd [value]) → void?
efd : eventfd?
value : exact-nonnegative-integer? = 1

Post given value to the semaphore.

procedure
(eventfd-wait efd) → exact-nonnegative-integer?
efd : eventfd?

Wait until the semaphore represented by the descriptor becomes higher than zero and then return either it’s value, resetting it back to zero (when #:semaphore? set to #f) or return just 1, decrementing the semaphore.

procedure
(eventfd-fd efd) → exact-nonnegative-integer?
efd : eventfd?

Return event descriptor as an integer.