From 6406acb5e3365ee9d47d5766393ac260dab3d019 Mon Sep 17 00:00:00 2001
From: Tim Vaughan <plugd@thelambdalab.xyz>
Date: Mon, 26 Apr 2021 22:16:04 +0200
Subject: [PATCH] Local proof-of-principle working.

---
 sam.scm | 98 ++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 80 insertions(+), 18 deletions(-)

diff --git a/sam.scm b/sam.scm
index 82f3d7f..656338d 100644
--- a/sam.scm
+++ b/sam.scm
@@ -20,7 +20,16 @@
 
 (define this-machine (make-machine "localhost" 1234))
 
-(define next-actor-id 1)
+(define next-actor-id
+  (let ((mutex (make-mutex "actor id mutex"))
+        (next-id 1))
+    (lambda ()
+      (let ((res #f))
+        (mutex-lock! mutex)
+        (set! res next-id)
+        (set! next-id (+ next-id 1))
+        (mutex-unlock! mutex)
+        res))))
 
 (define (address-id address) (car address))
 (define (address-machine address) (cdr address))
@@ -34,7 +43,7 @@
 (define actor-table (make-hash-table))
 
 (define (make-actor beh)
-  (let* ((id next-actor-id))
+  (let* ((id (next-actor-id)))
     (hash-table-set! actor-table id beh)
     (make-address id this-machine)))
   
@@ -44,9 +53,9 @@
       (if (null? behaviour)
           (print "Warning: discarded message" message " to unknown actor " address)
           (match (apply (hash-table-ref actor-table id) (cons address message))
-            ('done (hash-table-delete! actor-table actor))
+            ('done (hash-table-delete! actor-table id))
             ('sleep 'do-nothing)
-            (new-beh (hash-table-set! actor-table actor new-beh)))))))
+            (new-beh (hash-table-set! actor-table id new-beh)))))))
 
 ;; Scheduler
 
@@ -59,7 +68,7 @@
   (apply (if (address-local? address)
              send-local-message
              send-network-message)
-         message))
+         (cons address message)))
 
 (define (send-local-message address . message)
   (mutex-lock! local-queue-mutex)
@@ -87,24 +96,77 @@
     (mutex-unlock! local-queue-mutex)
     res))
 
-(define scheduler-thread
-  (make-thread
+(define (start-scheduler)
+  (thread-start!
    (lambda ()
-     (let loop ((next-addressed-message (next-local-message)))
-       (apply deliver-message next-addressed-message)
-       (loop (next-local-message))))))
+     (let loop ()
+       (apply deliver-message (next-local-message))
+       (loop)))))
 
+;; Console
 
-;; Testing
-
-(thread-start! scheduler-thread)
+(define reader-queue-mutex (make-mutex "reader queue"))
+(define reader-available-mutex (make-mutex "reader available"))
+(mutex-lock! reader-available-mutex #f #f)
+(define reader-queue (make-fifo))
 
-(define println
+(define console
   (make-actor (lambda (self . message)
-                (apply print message)
+                (mutex-lock! reader-queue-mutex)
+                (fifo-push reader-queue (car message))
+                (mutex-unlock! reader-available-mutex)
+                (mutex-unlock! reader-queue-mutex)
                 'sleep)))
 
-(print println)
-(send-message println "Hello, world!")
+(define (next-reader)
+  (let ((res #f))
+    (mutex-lock! reader-available-mutex #f #f)
+    (mutex-lock! reader-queue-mutex)
+    (set! res (fifo-pop reader-queue))
+    (if (not (fifo-empty? reader-queue))
+        (mutex-unlock! reader-available-mutex))
+    (mutex-unlock! reader-queue-mutex)
+    res))
+
+(define (start-console)
+  (let loop ()
+    (let ((reader (next-reader)))
+      (##sys#thread-block-for-i/o! (current-thread) 0 #t)
+      (thread-yield!)
+      (send-message reader (read-line)))
+    (loop)))
+
+
+;; System interface
+
+(define system
+  (make-actor (lambda (self . message)
+                (match message
+                  (('shutdown)
+                   (print "## System actor received shutdown message.")
+                   (exit 0)
+                   'done)
+                  (('println strings ...)
+                   (apply print strings)
+                   'sleep)))))
+
+;; Testing
+
+
+(send-message system 'println "Hello, what is your name?")
+(send-message console
+              (make-actor (lambda (self . message)
+                            (match message
+                              ((name)
+                               (send-message system 'println "Hello, " name "!")
+                               'done)))))
+
+(thread-start!
+ (lambda ()
+   (thread-sleep! 10)
+   (send-message system 'shutdown)))
+
+(start-scheduler)
+(start-console)
 
-(thread-join! scheduler-thread)
+;; (thread-join! scheduler-thread)
-- 
2.20.1