expose wrapped-exception introspect things for debugging

[8sync.git] / eightsync / agenda.scm

diff --git a/eightsync/agenda.scm b/eightsync/agenda.scm
index 386752695c41968c96a81df2d13e86983dae2220..9f54e17aa06ca2faf76c652de922e803bfb027af 100644 (file)
--- a/eightsync/agenda.scm
+++ b/eightsync/agenda.scm
@@ -65,6 +65,14 @@
 
             %port-request %run %run-at %run-delay
             
+            catch-8sync catch-%8sync
+
+            ;; used for introspecting the error, but a method for making
+            ;; is not exposed
+            wrapped-exception?
+            wrapped-exception-key wrapped-exception-args
+            wrapped-exception-stacks
+
             print-error-and-continue
 
             %current-agenda
@@ -434,42 +442,19 @@ Will produce (0 . 0) instead of a negative number, if needed."
 ;;; Asynchronous escape to run things
 ;;; =================================
 
-;; The future's in futures
-;; @@: ... kinda conflicts with ice-9 futures.  Should we rename
-;;   to "futurists"? :)
-
-(define (make-future call-first on-success on-fail on-error)
-  ;; TODO: add error stuff here
-  (lambda ()
-    (let ((call-result (call-first)))
-      ;; queue up calling the 
-      (run (on-success call-result)))))
-
 (define (agenda-on-error agenda)
   (const #f))
 
 (define (agenda-on-fail agenda)
   (const #f))
 
-(define* (request-future call-first on-success
-                         #:key
-                         (agenda (%current-agenda))
-                         (on-fail (agenda-on-fail agenda))
-                         (on-error (agenda-on-error agenda))  
-                         (when #f))
-  ;; TODO: error handling
-  ;; do we need some distinction between expected, catchable errors,
-  ;; and unexpected, uncatchable ones?  Probably...?
-  (make-run-request
-   (make-future call-first on-success on-fail on-error)
-   when))
-
 (define-syntax-rule (%8sync async-request)
   "Run BODY asynchronously at a prompt, passing args to make-future.
 
 Runs things asynchronously (8synchronously?)"
-  (abort-to-prompt (current-agenda-prompt)
-                   async-request))
+  (propagate-%async-exceptions
+   (abort-to-prompt (current-agenda-prompt)
+                    async-request)))
 
 ;; Async port request and run-request meta-requests
 (define (make-async-request proc)
@@ -490,16 +475,62 @@ return the wrong thing via (%8sync) and trip themselves up."
               "Invalid request passed back via an (%8sync) procedure."
               async-request))))
 
+(define-record-type <wrapped-exception>
+  (make-wrapped-exception key args stacks)
+  wrapped-exception?
+  (key wrapped-exception-key)
+  (args wrapped-exception-args)
+  (stacks wrapped-exception-stacks))
+
+(define-syntax-rule (propagate-%async-exceptions body)
+  (let ((body-result body))
+    (if (wrapped-exception? body-result)
+        (throw '8sync-caught-error
+               (wrapped-exception-key body-result)
+               (wrapped-exception-args body-result)
+               (wrapped-exception-stacks body-result))
+        body-result)))
+
 (define-syntax-rule (%run body ...)
   (%run-at body ... #f))
 
 (define-syntax-rule (%run-at body ... when)
+  ;; Send an asynchronous request to apply a continuation to the
+  ;; following function, then handle that as a request to the agenda
   (make-async-request
    (lambda (kont)
+     ;; We're making a run request
      (make-run-request
+      ;; Wrapping the following execution to run...
       (wrap
+       ;; Once we get the result from the inner part, we'll resume
+       ;; this continuation, but first
+       ;; @@: Is this running immediately, or queueing the result
+       ;;   after evaluation for the next agenda tick?  It looks
+       ;;   like evaluating immediately.  Is that what we want?
        (kont
-        (begin body ...)))
+        ;; Any unhandled errors are caught
+        (let ((exception-stack #f))
+          (catch #t
+            ;; Run the actual code the user requested
+            (lambda ()
+              body ...)
+            ;; If something bad happened and we didn't catch it,
+            ;; we'll wrap it up in such a way that the continuation
+            ;; can address it
+            (lambda (key . args)
+              (cond
+               ((eq? key '8sync-caught-error)
+                (match args
+                  ((orig-key orig-args orig-stacks)
+                   (make-wrapped-exception
+                    orig-key orig-args
+                    (cons exception-stack orig-stacks)))))
+               (else
+                (make-wrapped-exception key args
+                                        (list exception-stack)))))
+            (lambda _
+              (set! exception-stack (make-stack #t 1 0)))))))
       when))))
 
 (define-syntax-rule (%run-delay body ... delay-time)
@@ -519,6 +550,22 @@ return the wrong thing via (%8sync) and trip themselves up."
        (lambda ()
          body ...)))))
 
+(define-syntax-rule (catch-8sync exp (handler-key handler) ...)
+  (catch '8sync-caught-error
+    (lambda ()
+      exp)
+    (lambda (_ orig-key orig-args orig-stacks)
+      (cond
+       ((or (eq? handler-key #t)
+            (eq? orig-key handler-key))
+        (apply handler orig-stacks orig-args)) ...
+       (else (raise '8sync-caught-error
+                    orig-key orig-args orig-stacks))))))
+
+;; Alias...?
+(define-syntax-rule (catch-%8sync rest ...)
+  (catch-8sync rest ...))
+
 
 \f
 ;;; Execution of agenda, and current agenda