WIP

libs/cyclone/futures.scm

@@ -3,15 +3,26 @@
 ;; https://clojure.github.io/clojure/clojure.core-api.html#clojure.core/future?
 ;; https://purelyfunctional.tv/guide/clojure-concurrency/#future
 
+(define-library (futures)
   (import (scheme base)
           (scheme write)
           (cyclone concurrency)
           (srfi 18)
   )
-
-(define *future-sym* (string->symbol "  future  "))
-(define (future? obj)
-  (and (vector? obj) (eq? (vector-ref obj 0) *future-sym*)))
+  (export
+    future?
+    future-call
+    future-deref
+  )
+;(define *future-sym* (string->symbol "  future  "))
+;(define (future? obj)
+;  (and (vector? obj) (eq? (vector-ref obj 0) *future-sym*)))
+  (define-record-type <future>
+    (make-future done result lock)
+    future?
+    (done get-done set-done!)
+    (result get-result set-result!)
+    (lock get-lock set-lock!))
 
 
 ;; TODO: macro (future expr ...)
@@ -24,18 +35,38 @@
 ; of deref with timeout is used. See also - realized?.
 
 (define (future-call thunk)
-  (let ((ftr (vector *future-sym* 'todo)))
-    ;; TODO: setup and call the thread here
-
-;; Sketching out what is needed:
-;;(define (sum-entry-pt)
-;;  (sum-loop (* 100 100 100)))
-;;
-;;;; Thread - Do something, then let main thread know when we are done
-;;(define t9 (make-thread sum-entry-pt))
-;;(thread-start! t1)
-
+  (let* (
+         (lock (make-mutex))
+         (ftr (make-future #f #f lock)
+             ; (vector 
+             ;   *future-sym*  ;; Type indicator
+             ;   #f            ;; Done?
+             ;   #f            ;; Result
+             ;   lock)
+         )
+         (tfnc (lambda ()
+                 (mutex-lock! lock) 
+                 (let ((result (thunk))) ;; TODO: Catch exceptions (?)
+                   (set-done! #t)
+                   (set-result! result)
+                   ;(vector-set! ftr 1 #t) ;; Done
+                   ;(vector-set! ftr 2 result)
+                   (mutex-unlock! lock) 
+                 )))
+         (t (make-thread tfnc))
+        )
+    (thread-start! t)
     ftr))
 
 
-TODO: custom deref but eventually need to fold that functionality back into the main one
+;;TODO: custom deref but eventually need to fold this functionality back into the main one
+(define (future-deref ftr)
+  (when (not (future? ftr))
+    (error "Expected future but received" ftr))
+  (let ((result #f))
+    (mutex-lock!   (get-lock ftr)) ;(vector-ref ftr 3))
+    (set! result   (get-result ftr)) ;(vector-ref ftr 2))
+    (mutex-unlock! (get-lock ftr)) ;(vector-ref ftr 3))
+    result))
+
+))