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Added compare-and-set!

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This commit is contained in:
Justin Ethier 2019-05-30 18:42:15 -04:00
parent 5f517f6029
commit ebb8a2d6cd
1 changed files with 24 additions and 7 deletions
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31
libs/cyclone/atomics.scm
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@ -47,21 +47,38 @@
(define-c ref
"(void *data, int argc, closure _, object k, object obj)"
" atomic a;
if (Cyc_is_atomic(obj) != boolean_t) {
Cyc_rt_raise2(data, \"Type error: expected atom\", obj);
}
Cyc_check_atomic(data, obj);
a = (atomic) obj;
return_closcall1(data, k, ck_pr_load_ptr(&(a->obj)));")
;; TODO:
;; - swap, see https://clojure.github.io/clojure/clojure.core-api.html#clojure.core/swap!
;; (swap! atom f)(swap! atom f x)(swap! atom f x y)(swap! atom f x y & args)
(define (swap! atom f . opts)
'TODO)
;; TODO:
;; - compare and swap?
;; (compare-and-set! atom oldval newval)
;; https://clojuredocs.org/clojure.core/compare-and-set!
;; Atomically sets the value of atom to newval if and only if the
;; current value of the atom is identical to oldval. Returns true if
;; set happened, else false
(define-c compare-and-set!
"(void *data, int argc, closure _, object k, object obj, object oldval, object newval)"
" atomic a;
Cyc_check_atomic(data, obj);
a = (atomic) obj;
bool result = ck_pr_cas_ptr(&(a->obj), oldval, newval);
object rv = result ? boolean_t : boolean_f;
return_closcall1(data, k, rv); ")
(define a (make-atom '(1 2)))
(define lis '(1 2))
(define a (make-atom lis))
(write
(list
a
(ref a)))
(ref a)
(compare-and-set! a 1 lis)
(ref a)
(compare-and-set! a lis 1)
(ref a)
))