Keep passive clocks in a weak queue.

src/core/clock.ml

@@ -213,14 +213,16 @@ let _sync ?(pending = false) x =
 
 let sync c = _sync (Unifier.deref c)
 let cleanup_source s = try s#force_sleep with _ -> ()
-let clocks = Queue.create ()
+let passive_clocks = WeakQueue.create ()
+let active_clocks = Queue.create ()
 
 let rec _cleanup ~clock { outputs; passive_sources; active_sources } =
   Queue.iter outputs cleanup_source;
   WeakQueue.iter passive_sources cleanup_source;
   WeakQueue.iter active_sources cleanup_source;
   Queue.iter clock.sub_clocks stop;
-  Queue.filter clocks (fun c -> Unifier.deref c == clock)
+  WeakQueue.filter passive_clocks (fun c -> Unifier.deref c == clock);
+  Queue.filter active_clocks (fun c -> Unifier.deref c == clock)
 
 and stop c =
   let clock = Unifier.deref c in
@@ -259,7 +261,8 @@ let unify =
       (Queue.push clock'.pending_activations);
     Queue.flush_iter clock.sub_clocks (Queue.push clock'.sub_clocks);
     Queue.flush_iter clock.on_error (Queue.push clock'.on_error);
-    Queue.filter clocks (fun el -> el != c);
+    Queue.filter active_clocks (fun el -> el != c);
+    WeakQueue.filter passive_clocks (fun el -> el != c);
     Unifier.(clock.id <-- clock'.id);
     Unifier.(c <-- c')
   in
@@ -281,7 +284,7 @@ let unify =
 let () =
   Lifecycle.before_core_shutdown ~name:"Clocks stop" (fun () ->
       Atomic.set global_stop true;
-      Queue.iter clocks (fun c -> if sync c <> `Passive then stop c))
+      Queue.iter active_clocks stop)
 
 let _animated_sources { outputs; active_sources } =
   Queue.elements outputs @ WeakQueue.elements active_sources
@@ -421,7 +424,7 @@ and _tick ~clock x =
   check_stopped ();
   _after_tick ~clock x;
   check_stopped ();
-  Queue.iter clocks start
+  Queue.iter active_clocks start
 
 and _clock_thread ~clock x =
   let has_sources_to_process () =
@@ -527,7 +530,9 @@ let create ?(stack = []) ?on_error ?(id = "generic") ?(sub_ids = [])
         on_error = on_error_queue;
       }
   in
-  Queue.push clocks c;
+  (match sync with
+    | `Passive -> WeakQueue.push passive_clocks c
+    | _ -> Queue.push active_clocks c);
   c
 
 let time c =
@@ -536,7 +541,7 @@ let time c =
   Time.to_float (_time c)
 
 let start_pending () =
-  let c = Queue.flush_elements clocks in
+  let c = Queue.flush_elements active_clocks in
   let c = List.map (fun c -> (c, Unifier.deref c)) c in
   let c = List.sort_uniq (fun (_, c) (_, c') -> Stdlib.compare c c') c in
   List.iter
@@ -547,7 +552,7 @@ let start_pending () =
               | `True sync -> _start ~sync clock
               | `False -> ())
         | _ -> ());
-      Queue.push clocks c)
+      Queue.push active_clocks c)
     c
 
 let () =
@@ -594,4 +599,4 @@ let create ?stack ?on_error ?id ?sync () = create ?stack ?on_error ?id ?sync ()
 let clocks () =
   List.sort_uniq
     (fun c c' -> Stdlib.compare (Unifier.deref c) (Unifier.deref c'))
-    (Queue.elements clocks)
+    (Queue.elements active_clocks @ WeakQueue.elements passive_clocks)