🐛 Fix unexpected rx scheduler saturation on mouse movement burst

Fixed with custom trailing-edge throttling mechanism

frontend/src/app/main/data/workspace/notifications.cljs

@@ -19,6 +19,7 @@
    [app.util.globals :refer [global]]
    [app.util.mouse :as mse]
    [app.util.object :as obj]
+   [app.util.rxops :as rxs]
    [app.util.time :as dt]
    [beicon.v2.core :as rx]
    [clojure.set :as set]
@@ -82,7 +83,7 @@
                              ;; position changes.
                              (->> stream
                                   (rx/filter mse/pointer-event?)
-                                  (rx/sample 50)
+                                  (rx/pipe (rxs/throttle 100))
                                   (rx/map #(handle-pointer-send file-id (:pt %)))))
 
                             (rx/take-until stoper))]

frontend/src/app/util/rxops.cljs

@@ -0,0 +1,72 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) KALEIDOS INC
+
+(ns app.util.rxops
+  (:require
+   [beicon.v2.core :as rx]))
+
+(defn- throttle-fn
+  [delay f]
+  (let [state
+        #js {:lastExecTime 0
+             :timeoutId nil
+             :context nil
+             :args nil}
+
+        execute-fn
+        (fn []
+          (let [context (.-context ^js state)
+                args    (.-args ^js state)]
+            (.apply f context args)
+            (set! (.-lastExecTime state) (js/Date.now))
+            (set! (.-timeoutId state) nil)))
+
+        wrapped-fn
+        (fn []
+          (let [ctime (js/Date.now)
+                ltime (.-lastExecTime ^js state)
+                args  (js-arguments)]
+
+            (this-as this
+              (set! (.-context state) this)
+              (set! (.-args state) args))
+
+            (let [timeout-id (.-timeoutId state)]
+              (if (>= (- ctime ltime) delay)
+                (do
+                  (when ^boolean timeout-id
+                    (js/clearTimeout timeout-id)
+                    (set! (.-timeoutId state) nil))
+                  (execute-fn))
+
+                (when-not ^boolean timeout-id
+                  (set! (.-timeoutId state)
+                        (js/setTimeout execute-fn (- delay ctime ltime))))))))]
+
+    (specify! wrapped-fn
+      rx/IDisposable
+      (-dispose [_]
+        (js/clearTimeout (.-timeoutId state))
+        (set! (.-lastExecTime state) 0)
+        (set! (.-timeoutId state) nil)))))
+
+
+(defn throttle
+  "High performance rxjs throttle operation. It does not saturates the
+  macro-task queue of the js runtime on long burst of mouse
+  movements."
+  [delay]
+  (fn [source]
+    (rx/create
+     (fn [subs]
+       (let [next-fn  (throttle-fn delay (partial rx/push! subs))
+             error-fn (fn [cause]
+                        (rx/dispose! next-fn)
+                        (rx/error! subs cause))
+             end-fn   (fn []
+                        (rx/dispose! next-fn)
+                        (rx/end! subs))]
+         (rx/sub! source next-fn error-fn end-fn))))))