Extensions to Gambit threads can be done currently using the define-type-of-thread special form. For example:
(define-type-of-thread mythread constructor: construct-mythread errptr)
(define (make-mythread thunk) (thread-init! (construct-mythread #f) thunk))
(define t (make-mythread (lambda () (pp (mythread-errptr (current-thread))))))
(mythread-errptr-set! t 'foo)
(thread-start! t)
(thread-join! t)
So I don’t see the need for adding this feature to the basic Gambit threads.
Marc
On Mar 10, 2018, at 8:45 AM, Dimitris Vyzovitis vyzo@hackzen.org wrote:
Marc,
Could we add thread-cells? They can be easily implemented with a per-thread hash-table, that only gets initialized if accessed.
They are incredibly useful for per thread caches, and probably a lot of other things.
For instance, I have this common pattern that i see a lot:
(def errptr-cache (make-hash-table-eq weak-keys: #t)) (def errptr-cache-mutex (make-mutex))
(def (get-errptr) (with-lock errptr-cache-mutex (lambda () (cond ((hash-get errptr-cache (current-thread)) => (lambda (errptr) (errptr_clear errptr) errptr)) (else (let (errptr (check-ptr get-errptr (make_errptr))) (hash-put! errptr-cache (current-thread) errptr) errptr))))))
and I would like to eliminate both the lock and the weak table.
I can add it and make a pr, but I wanted to consult with you first.
-- vyzo