From 9af8adee793eb5919d017616aff64274cd42270c Mon Sep 17 00:00:00 2001
From: Tony Garnock-Jones <tonygarnockjones@gmail.com>
Date: Fri, 27 Jun 2014 16:26:46 -0400
Subject: [PATCH] actorise the relay

---
 minimart/relay.rkt | 89 +++++++++++++++++++---------------------------
 1 file changed, 37 insertions(+), 52 deletions(-)

diff --git a/minimart/relay.rkt b/minimart/relay.rkt
index bc63358..093161a 100644
--- a/minimart/relay.rkt
+++ b/minimart/relay.rkt
@@ -42,63 +42,48 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Connections
 
-(struct connection-state (client-id tunnelled-gestalt) #:transparent)
-
 (define (ping-interval) (* 1000 (max (- (ws-idle-timeout) 10) (* (ws-idle-timeout) 0.8))))
 
 (define (spawn-connection-handler c server-id)
-  (define (send-event e s)
-    (send (websocket-message server-id
-			     (connection-state-client-id s)
-			     (jsexpr->string (lift-json-event e)))
-	  #:meta-level 1))
-  (define ((handle-connection-routing-change g) s)
-    (if (gestalt-empty? g)
-	(transition s (quit)) ;; websocket connection closed
-	#f))
-  (define ((handle-tunnelled-routing-change g) s)
-    (transition s (send-event (routing-update g) s)))
-  (define ((handle-tunnellable-message m) s)
-    (if (gestalt-accepts? (connection-state-tunnelled-gestalt s) m)
-	(transition s (send-event m s))
-	(transition s '())))
-  (define relay-connections
-    (gestalt-union (sub (timer-expired c ?) #:meta-level 1)
-		   (sub (websocket-message c server-id ?) #:meta-level 1)
-		   (sub (websocket-message c server-id ?) #:meta-level 1 #:level 1)
-		   (pub (websocket-message server-id c ?) #:meta-level 1)))
-  (define (connection-handler e s)
-    (match e
-      [(routing-update g)
-       (sequence-transitions
-	(transition s '())
-	(handle-connection-routing-change (gestalt-filter g relay-connections))
-	(handle-tunnelled-routing-change
-	 (gestalt-filter g (connection-state-tunnelled-gestalt s))))]
-      [(? message? m)
-       (sequence-transitions
-	(match m
-	  [(message (websocket-message from to data) 1 #f)
-	   (match (drop-json-action (string->jsexpr data))
+  (actor #:name relay
+	 #:state [tunnelled-gestalt (gestalt-empty)]
+
+	 (send #:meta-level 1 (set-timer c (ping-interval) 'relative))
+	 (subscribe (timer-expired c ?)
+	   #:meta-level 1
+	   (send #:meta-level 1 (set-timer c (ping-interval) 'relative))
+	   (send-event 'ping))
+
+	 (observe-advertisers (websocket-message c server-id ?)
+	   #:meta-level 1
+	   #:presence peer-connected?
+	   (when (not peer-connected?) (quit)))
+
+	 (advertise (websocket-message server-id c ?) #:meta-level 1)
+	 (subscribe (websocket-message c server-id ($ data))
+	   #:meta-level 1
+	   #:run-transition (handle-incoming (drop-json-action (string->jsexpr data))))
+
+	 (define (handle-incoming data)
+	   (match data
 	     [(routing-update g-unfiltered)
 	      (define g (gestalt-transform g-unfiltered
-					   (lambda (ml l p) (if (zero? ml) p '(#f . #f)))))
-	      (transition (struct-copy connection-state s [tunnelled-gestalt g])
-			  (routing-update (gestalt-union g relay-connections)))]
+	 				   (lambda (ml l p) (if (zero? ml) p '(#f . #f)))))
+	      (begin-transition
+	 	#:update [tunnelled-gestalt g]
+	 	#:update-routes)]
 	     [(? message? m)
-	      (transition s (if (zero? (message-meta-level m)) m '()))]
+	      (begin-transition
+	 	(when (zero? (message-meta-level m)) m))]
 	     ['ping
-	      (transition s (send-event 'pong s))]
+	      (begin-transition (send-event 'pong))]
 	     ['pong
-	      (transition s '())])]
-	  [(message (timer-expired _ _) 1 #f)
-	   (transition s (list (send (set-timer c (ping-interval) 'relative) #:meta-level 1)
-			       (send-event 'ping s)))]
-	  [_
-	   (transition s '())])
-	(handle-tunnellable-message m))]
-      [#f #f]))
-  (list (send (set-timer c (ping-interval) 'relative) #:meta-level 1)
-	(spawn connection-handler
-	       (connection-state c (gestalt-empty))
-	       relay-connections)))
+	      (begin-transition)]))
+
+	 (observe-gestalt tunnelled-gestalt
+	   [event ;; routing-update or message, prefiltered by tunnelled-gestalt
+	    (send-event event)])
+
+	 (define (send-event e)
+	   (send #:meta-level 1
+		 (websocket-message server-id c (jsexpr->string (lift-json-event e)))))))