use a linked list for the async iterable queue so that eviction is O(1)

Author: afshin

packages/polling/package.json

@@ -38,6 +38,7 @@
     "watch": "tsc --build --watch"
   },
   "dependencies": {
+    "@lumino/collections": "^2.0.4",
     "@lumino/coreutils": "^2.2.2",
     "@lumino/disposable": "^2.1.5",
     "@lumino/signaling": "^2.1.5"

packages/polling/src/poll.ts

@@ -1,6 +1,8 @@
 // Copyright (c) Jupyter Development Team.
 // Distributed under the terms of the Modified BSD License.
 
+import { LinkedList } from '@lumino/collections';
+
 import { JSONExt, PromiseDelegate } from '@lumino/coreutils';
 
 import { IObservableDisposable } from '@lumino/disposable';
@@ -142,18 +144,19 @@ export class Poll<T = any, U = any, V extends string = 'standby'>
    * Return an async iterator that yields every tick.
    */
   async *[Symbol.asyncIterator](): AsyncIterableIterator<IPoll.State<T, U, V>> {
-    const queue: IPoll.State<T, U, V>[] = [this.state];
+    const queue = new LinkedList<IPoll.State<T, U, V>>();
     const enqueue = (_: unknown, state: IPoll.State<T, U, V>) => {
       if (queue.length >= Private.MAX_QUEUE_SIZE) {
-        queue.shift();
+        queue.removeFirst();
       }
-      queue.push(state);
+      queue.addLast(state);
     };
+    queue.addLast(this.state);
     this.ticked.connect(enqueue);
     try {
       while (!this.isDisposed) {
-        if (queue.length) {
-          yield queue.shift()!;
+        if (!queue.isEmpty) {
+          yield queue.removeFirst()!;
         } else {
           await this.tick.catch(() => undefined);
         }

yarn.lock

@@ -697,6 +697,7 @@ __metadata:
   resolution: "@lumino/polling@workspace:packages/polling"
   dependencies:
     "@lumino/buildutils": ^2.0.3
+    "@lumino/collections": ^2.0.4
     "@lumino/coreutils": ^2.2.2
     "@lumino/disposable": ^2.1.5
     "@lumino/signaling": ^2.1.5