erlang: receive...after Ms timeout clause (+9 tests)

lib/erlang/runtime.sx

@@ -193,6 +193,8 @@
             :continuation nil
             :receive-pats nil
             :trap-exit false
+            :has-timeout false
+            :timed-out false
             :exit-reason nil}))
         (dict-set! (er-sched-processes) (er-pid-key pid) proc)
         (er-sched-enqueue! pid)
@@ -292,10 +294,40 @@
     ()
     (let
       ((pid (er-sched-next-runnable!)))
-      (when
+      (cond
         (not (= pid nil))
-        (er-sched-step! pid)
-        (er-sched-run-all!)))))
+        (do (er-sched-step! pid) (er-sched-run-all!))
+        ;; Queue empty — fire one pending receive-with-timeout and go again.
+        (er-sched-fire-one-timeout!) (er-sched-run-all!)
+        :else nil))))
+
+;; Wake one waiting process whose receive had an `after Ms` clause.
+;; Returns true if one fired. In our synchronous model "time passes"
+;; once the runnable queue drains — timeouts only fire then.
+(define
+  er-sched-fire-one-timeout!
+  (fn
+    ()
+    (let
+      ((ks (keys (er-sched-processes))) (fired (list false)))
+      (for-each
+        (fn
+          (k)
+          (when
+            (not (nth fired 0))
+            (let
+              ((p (get (er-sched-processes) k)))
+              (when
+                (and
+                  (= (get p :state) "waiting")
+                  (get p :has-timeout))
+                (dict-set! p :timed-out true)
+                (dict-set! p :has-timeout false)
+                (dict-set! p :state "runnable")
+                (er-sched-enqueue! (get p :pid))
+                (set-nth! fired 0 true)))))
+        ks)
+      (nth fired 0))))
 
 (define
   er-sched-step!