First round of trivial-bug fixes and tweaks

os.rkt

@@ -6,7 +6,22 @@
 (require racket/list)
 (require "functional-queue.rkt")
 
-(provide ...)
+(provide
+ ;; Actions/Events
+ (struct-out message)
+ (struct-out process)
+
+ ;; Kernel Events
+ (struct-out meta-message)
+
+ ;; Event handlers and kernel requests
+ (struct-out event-handler)
+ (struct-out kernel-mode-transition)
+
+ ;; VMs
+ make-vm
+ run-vm
+)
 
 ;; Each VM hosts 0 or more *multiplexed* processes. Each process has
 ;; its own state record. In between schedulings, a process consists of
@@ -79,8 +94,8 @@
 ;; the process, and the output is the information passed back to the
 ;; VM when the process yields the CPU.
 
-;; A BootK is a (Void -> KernelModeTransition), effectively an
-;; InterruptK with a void initial process state.
+;; A BootK is a ( -> KernelModeTransition), effectively an InterruptK
+;; with a void initial process state.
 
 ;; A KernelModeTransition is a
 ;; (kernel-mode-transition ProcessState
@@ -108,12 +123,14 @@
 ;; TODO: timeouts
 
 (define (make-vm boot)
-  (boot-process boot (vm (list) (make-queue) (make-queue))))
+  (boot-process boot (vm (list) (make-queue))))
 
 (define (subscribe-process process-state event-handlers state)
-  (struct-copy vm state [subscriptions (cons (subscription process-state
-							   event-handlers)
-					     (vm-subscriptions state))]))
+  (if (null? event-handlers)
+      state ;; dead process because no continuations offered
+      (struct-copy vm state [subscriptions (cons (subscription process-state
+							       event-handlers)
+						 (vm-subscriptions state))])))
 
 (define (enqueue-event event state)
   (struct-copy vm state [pending-events (cons event (vm-pending-events state))]))
@@ -125,7 +142,7 @@
   (define state-after-events
     (foldl dispatch-event
 	   (struct-copy vm state-after-timeouts [pending-events (make-queue)])
-	   (vm-pending-events state)))
+	   (queue->list (vm-pending-events state))))
   (trap-to-metalevel state-after-events))
 
 (define (dispatch-event event state)
@@ -148,7 +165,7 @@
       (search-handlers (cdr event-handlers))])))
 
 (define (boot-process k state)
-  (run-process (void) k state))
+  (run-process (void) (lambda (dummy) (k)) state))
 
 (define (run-process process-state k state)
   (match (k process-state)
@@ -157,11 +174,13 @@
 			     new-event-handlers)
      (subscribe-process new-process-state
 			new-event-handlers
-			(foldl enqueue-event state outbound-events))]))
+			(foldl enqueue-event state outbound-events))]
+    [other
+     (error 'vm "Processes must return a kernel-mode-transition struct; got ~v" other)]))
 
 (define (trap-to-metalevel state)
   (define-values (meta-messages non-meta-messages)
-    (partition meta-message? (vm-pending-events state)))
+    (partition meta-message? (queue->list (vm-pending-events state))))
   (define-values (processes remainder)
     (partition process? non-meta-messages))
   (define-values (messages junk)
@@ -170,7 +189,7 @@
     (struct-copy vm (foldl (lambda (p state) (boot-process (process-boot p) state))
 			   state
 			   processes)
-		 [pending-events messages]))
+		 [pending-events (list->queue messages)]))
   (define outbound-meta-messages 
     (map (lambda (mm) (message (meta-message-body mm))) meta-messages))
   (kernel-mode-transition