From 4a1a9a9f5228536a625c758a12b3341d3dee696a Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Thu, 11 Jul 2019 11:13:25 -0400
Subject: [PATCH] WIP

---
 libs/cyclone/delay-promise.scm | 67 +++++++++++++++++++++++-----------
 1 file changed, 46 insertions(+), 21 deletions(-)

diff --git a/libs/cyclone/delay-promise.scm b/libs/cyclone/delay-promise.scm
index cd5d956c..3bd26af7 100644
--- a/libs/cyclone/delay-promise.scm
+++ b/libs/cyclone/delay-promise.scm
@@ -3,34 +3,34 @@
 
 (import (scheme write) (scheme base) (cyclone concurrent) (srfi 18))
 
-(define-record-type <delay>
-  (%make-delay done result lock)
-  delay?
-  (done delay:done delay:set-done!)
-  (value delay:value delay:set-value!) ;; Either thunk or result
-  (lock delay:lock delay:set-lock!))
+(define-record-type <shared-delay>
+  (%make-shared-delay done result lock)
+  shared-delay?
+  (done sd:done sd:set-done!)
+  (value sd:value sd:set-value!) ;; Either thunk or result
+  (lock sd:lock sd:set-lock!))
 
-(define (make-delay thunk)
-  (%make-delay #f thunk (make-mutex)))
+(define (make-shared-delay thunk)
+  (%make-shared-delay #f thunk (make-mutex)))
 
-(define (delay-deref d)
-  (when (not (delay? d))
+(define (shared-delay-deref d)
+  (when (not (shared-delay? d))
     (error "Expected future but received" d))
-  (mutex-lock! (delay:lock d))
+  (mutex-lock! (sd:lock d))
   (cond
-    ((delay:done d) 
-     (delay:value d))
+    ((sd:done d) 
+     (sd:value d))
     (else
-     (delay:set-value! d 
-       (make-shared ((delay:value d)))) ;; Exec thunk and store result
-     (delay:set-done! d #t)))
-  (mutex-unlock! (delay:lock d))
+     (sd:set-value! d 
+       (make-shared ((sd:value d)))) ;; Exec thunk and store result
+     (sd:set-done! d #t)))
+  (mutex-unlock! (sd:lock d))
 )
 
 (define-syntax shared-delay
   (er-macro-transformer
    (lambda (expr rename compare)
-     `(make-delay (lambda () ,(cadr expr))))))
+     `(make-shared-delay (lambda () ,(cadr expr))))))
 
 
 (define (test)
@@ -38,6 +38,31 @@
   'done)
 
 (define d (shared-delay (test)))
-(write (delay-deref d))(newline)
-(write (delay-deref d))(newline)
-(write (delay-deref d))(newline)
+(write (shared-delay-deref d))(newline)
+(write (shared-delay-deref d))(newline)
+(write (shared-delay-deref d))(newline)
+
+
+;; Promises
+
+(define-record-type <shared-promise>
+  (%make-shared-promise done value lock cv)
+  shared-promise?
+  (done sp:done sp:set-done!)
+  (value sp:value sp:set-value!)
+  (lock sp:lock sp:set-lock!)
+  (cv sp:cv sp:set-cv!))
+
+(define (make-shared-promise)
+  (%make-shared-promise #f #f (make-mutex) (make-condition-variable)))
+
+(define (shared-promise-deref obj)
+  ;; TODO: block on CV until ready
+  ;; return sp:value
+)
+
+(define (deliver obj)
+  ;; TODO: if not delivered, compute value and signal all on the cv
+  ;;       else, do nothing
+)
+