actors: Add docstring to hive-create-actor*.
[8sync.git] / 8sync / actors.scm
index c694c489992abd9a99a9aca57f2afc605103e822..9b079b8a1754c788ac860a8cbccf78904f1a5b42 100644 (file)
@@ -70,7 +70,7 @@
 
             message-auto-reply?
 
-            <- <-wait <-reply <-reply-wait
+            <- <-wait <-wait* <-reply <-reply-wait <-reply-wait*
 
             call-with-message msg-receive msg-val
 
 ;;; See: https://web.archive.org/web/20081223021934/http://mumble.net/~jar/articles/oo-moon-weinreb.html
 ;;;   (also worth seeing: http://mumble.net/~jar/articles/oo.html )
 
+;; This is the internal, generalized message sending method.
+;; Users shouldn't use it!  Use the <-foo forms instead.
+
+;; @@: Could we get rid of some of the conditional checks through
+;;   some macro-foo?
+
+(define-inlinable (send-message send-options from-actor to-id action
+                                replying-to-message wants-reply?
+                                message-body-args)
+  (if replying-to-message
+      (set-message-replied! replying-to-message #t))
+  (let* ((hive (actor-hive from-actor))
+         (new-message
+          (make-message (hive-gen-message-id hive) to-id
+                        (actor-id from-actor) action
+                        message-body-args
+                        #:wants-reply wants-reply?
+                        #:in-reply-to
+                        (if replying-to-message
+                            (message-id replying-to-message)
+                            #f))))
+    (if wants-reply?
+        (abort-to-prompt (hive-prompt (actor-hive from-actor))
+                         from-actor new-message send-options)
+        ;; @@: It might be that eventually we pass in send-options
+        ;;   here too.  Since <-wait and <-reply-wait are the only ones
+        ;;   that use it yet, for now it kind of just makes things
+        ;;   confusing.
+        (8sync (hive-process-message hive new-message)))))
+
+
 (define (<- from-actor to-id action . message-body-args)
   "Send a message from an actor to another actor"
-  (let* ((hive (actor-hive from-actor))
-         (message (make-message (hive-gen-message-id hive) to-id
-                                (actor-id from-actor) action
-                                message-body-args)))
-    (8sync (hive-process-message hive message))))
+  (send-message '() from-actor to-id action
+                #f #f message-body-args))
+
+(define (<-wait* send-options from-actor to-id action . message-body-args)
+  "Like <-wait, but allows extra parameters, for example whether to
+#:accept-errors"
+  (apply wait-maybe-handle-errors
+         (send-message send-options from-actor to-id action
+                       #f #t message-body-args)
+         send-options))
 
 (define (<-wait from-actor to-id action . message-body-args)
   "Send a message from an actor to another, but wait until we get a response"
-  (let* ((hive (actor-hive from-actor))
-         (abort-to (hive-prompt (actor-hive from-actor)))
-         (message (make-message (hive-gen-message-id hive) to-id
-                                (actor-id from-actor) action
-                                message-body-args
-                                #:wants-reply #t)))
-    (abort-to-prompt abort-to from-actor message)))
+  (apply <-wait* '() from-actor to-id action message-body-args))
 
 ;; TODO: Intelligently ~propagate(ish) errors on -wait functions.
 ;;   We might have `send-message-wait-brazen' to allow callers to
 
 (define (<-reply from-actor original-message . message-body-args)
   "Reply to a message"
-  (set-message-replied! original-message #t)
-  (let* ((hive (actor-hive from-actor))
-         (new-message (make-message (hive-gen-message-id hive)
-                                    (message-from original-message)
-                                    (actor-id from-actor) '*reply*
-                                    message-body-args
-                                    #:in-reply-to (message-id original-message))))
-    (8sync (hive-process-message hive new-message))))
+  (send-message '() from-actor (message-from original-message) '*reply*
+                original-message #f message-body-args))
 
 (define (<-auto-reply from-actor original-message)
   "Auto-reply to a message.  Internal use only!"
-  (set-message-replied! original-message #t)
-  (let* ((hive (actor-hive from-actor))
-         (new-message (make-message (hive-gen-message-id hive)
-                                    (message-from original-message)
-                                    (actor-id from-actor) '*auto-reply*
-                                    '()
-                                    #:in-reply-to (message-id original-message))))
-    (8sync (hive-process-message hive new-message))))
+  (send-message '() from-actor (message-from original-message) '*auto-reply*
+                original-message #f '()))
+
+(define (<-reply-wait* send-options from-actor original-message
+                       . message-body-args)
+  "Reply to a messsage, but wait until we get a response"
+  (apply wait-maybe-handle-errors
+         (send-message send-options from-actor
+                       (message-from original-message) '*reply*
+                       original-message #t message-body-args)
+         send-options))
 
 (define (<-reply-wait from-actor original-message . message-body-args)
   "Reply to a messsage, but wait until we get a response"
-  (set-message-replied! original-message #t)
-  (let* ((hive (actor-hive from-actor))
-         (abort-to (hive-prompt (actor-hive from-actor)))
-         (new-message (make-message (hive-gen-message-id hive)
-                                    (message-from original-message)
-                                    (actor-id from-actor) '*reply*
-                                    message-body-args
-                                    #:wants-reply #t
-                                    #:in-reply-to (message-id original-message))))
-    (abort-to-prompt abort-to from-actor new-message)))
+  (apply <-reply-wait* '() from-actor original-message message-body-args))
+
+(define* (wait-maybe-handle-errors message
+                                   #:key accept-errors
+                                   #:allow-other-keys)
+  "Before returning a message to a waiting caller, see if we need to
+raise an exception if an error."
+  (define action (message-action message))
+  (cond ((and (eq? action '*error*)
+              (not accept-errors))
+         (throw 'hive-unresumable-coroutine
+                "Won't resume coroutine; got an *error* as a reply"
+                #:message message))
+        (else message)))
 
 
 \f
@@ -439,6 +470,14 @@ to come after class definition."
     ;; unresumable continuation.
     (lambda () (hive-process-message hive new-message))))
 
+(define-record-type <waiting-on-reply>
+  (make-waiting-on-reply actor-id kont send-options)
+  waiting-on-reply?
+  (actor-id waiting-on-reply-actor-id)
+  (kont waiting-on-reply-kont)
+  (send-options waiting-on-reply-send-options))
+
+
 (define-method (hive-process-message (hive <hive>) message)
   "Handle one message, or forward it via an ambassador"
   (define (maybe-autoreply actor)
@@ -488,11 +527,12 @@ to come after class definition."
           (8sync (queued-error-handling-thunk))))
     (call-with-prompt (hive-prompt hive)
       call-catching-errors
-      (lambda (kont actor message)
+      (lambda (kont actor message send-options)
         ;; Register the coroutine
         (hash-set! (hive-waiting-coroutines hive)
                    (message-id message)
-                   (cons (actor-id actor) kont))
+                   (make-waiting-on-reply
+                    (actor-id actor) kont send-options))
         ;; Send off the message
         (8sync (hive-process-message hive message)))))
 
@@ -512,45 +552,37 @@ to come after class definition."
              result))))))
 
   (define (resume-waiting-coroutine)
-    (cond
-     ((or (eq? (message-action message) '*reply*)
-          (eq? (message-action message) '*auto-reply*))
-      (call-catching-coroutine
-       (lambda ()
-         (match (hash-remove! (hive-waiting-coroutines hive)
-                              (message-in-reply-to message))
-           ((_ . (resume-actor-id . kont))
-            (if (not (equal? (message-to message)
-                             resume-actor-id))
-                (throw 'resuming-to-wrong-actor
-                       "Attempted to resume a coroutine to the wrong actor!"
-                       #:expected-actor-id (message-to message)
-                       #:got-actor-id resume-actor-id
-                       #:message message))
-            (let (;; @@: How should we resolve resuming coroutines to actors who are
-                  ;;   now gone?
-                  (actor (resolve-actor-to))
-                  (result (kont message)))
-              (maybe-autoreply actor)
-              result))
-           (#f (throw 'no-waiting-coroutine
-                      "message in-reply-to tries to resume nonexistent coroutine"
-                      message))))))
-     ;; Yikes, we must have gotten an error or something back
-     (else
-      ;; @@: Not what we want in the long run?
-      ;; What we'd *prefer* to do is to resume this message
-      ;; and throw an error inside the message handler
-      ;; (say, from send-mesage-wait), but that causes a SIGABRT (??!!)
-      (hash-remove! (hive-waiting-coroutines hive)
-                    (message-in-reply-to message))
-      (let ((explaination
-             (if (eq? (message-action message) '*reply*)
-                 "Won't resume coroutine; got an *error* as a reply"
-                 "Won't resume coroutine because action is not *reply*")))
-        (throw 'hive-unresumable-coroutine
-               explaination
-               #:message message)))))
+    (case (message-action message)
+      ;; standard reply / auto-reply
+      ((*reply* *auto-reply* *error*)
+       (call-catching-coroutine
+        (lambda ()
+          (match (hash-remove! (hive-waiting-coroutines hive)
+                               (message-in-reply-to message))
+            ((_ . waiting)
+             (if (not (equal? (message-to message)
+                              (waiting-on-reply-actor-id waiting)))
+                 (throw 'resuming-to-wrong-actor
+                        "Attempted to resume a coroutine to the wrong actor!"
+                        #:expected-actor-id (message-to message)
+                        #:got-actor-id (waiting-on-reply-actor-id waiting)
+                        #:message message))
+             (let* (;; @@: How should we resolve resuming coroutines to actors who are
+                    ;;   now gone?
+                    (actor (resolve-actor-to))
+                    (kont (waiting-on-reply-kont waiting))
+                    (result (kont message)))
+               (maybe-autoreply actor)
+               result))
+            (#f (throw 'no-waiting-coroutine
+                       "message in-reply-to tries to resume nonexistent coroutine"
+                       message))))))
+      ;; Unhandled action for a reply!
+      (else
+       (throw 'hive-unresumable-coroutine
+              "Won't resume coroutine, nonsense action on reply message"
+              #:action (message-action message)
+              #:message message))))
 
   (define (process-remote-message)
     ;; Find the ambassador
@@ -600,6 +632,7 @@ that method for documentation."
                       init #f))
 
 (define* (hive-create-actor* hive actor-class id-cookie #:rest init)
+  "Create an actor, but also add a 'cookie' to the name for debugging"
   (%hive-create-actor hive actor-class
                       init id-cookie))