Monitoring.

os2.rkt

@@ -55,6 +55,9 @@
 	 (rename-out [yield <yield>])
 	 (rename-out [at-meta-level <at-meta-level>])
 
+	 (struct-out monitor)
+	 spawn/monitor
+
 	 ;; Reexports from unify.rkt for convenience
 	 wild
 	 wild?
@@ -277,6 +280,24 @@
   (or (topic-virtual? local-topic)
       (not (topic-virtual? remote-topic))))
 
+;;---------------------------------------------------------------------------
+;; Monitoring.
+
+(struct monitor (pid debug-name) #:prefab)
+
+(define (spawn/monitor main [k #f] #:debug-name [debug-name #f])
+  ;; TODO: revisit the idea of points-of-attachment. There's an
+  ;; intermediate network between the processes and the kernel, and
+  ;; pid-level presence could be seen as object-level presence on that
+  ;; network somehow.
+  (define ((monitor-transition main-fn) self-pid)
+    (define m (monitor self-pid debug-name))
+    (prefix-transition (main-fn self-pid)
+      (role (list 'canary m) (topic-publisher m) #:state state)))
+  (make-spawn (monitor-transition (if (procedure? main) main (lambda (self-pid) main)))
+	      k
+	      #:debug-name debug-name))
+
 ;;---------------------------------------------------------------------------
 ;; Core virtualizable virtual machine.