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6.19 Timers

The (goblins actor-lib timers) module provides a mechanism to wait or sleep for a set amount of time. If the sleep procedure that comes with Guile/Fibers is used, this will cause the entire vat to stop and sleep, resulting in the vat being “blocked”. This is almost always is not what we want, which is where this module comes in, providing a mechanism to create Goblins promises which will resolve after a specified amount of time.

Since this is built upon Goblins promises, promise resolutions will be queued on the relevent vat queue, like all other messages, at the end of the vat’s message queue. This means that it could take longer to resolve than the time specified to sleep, how much time depends on the vat message queue at the moment.

Procedure: timeout seconds [result #t] ¶

Make a promise which will be fulfilled after seconds. The value the promise will be fulfilled with is the optional result.

(use-modules (goblins)
             (goblins actor-lib timer))

(on (timeout 1 'hello) pk)
;; After 1 second, we should see:
;;; (hello)