Merge pull request #1047 from rudycelekli/contrib/gods-026-map-subscription-ownership-20261011-reviewed

fix(maps): stop delivering settled state to detached subscribers

CHANGELOG.md

@@ -36,6 +36,8 @@
 
 - Director timeline seeks cross the dateline along the short longitude arc.
 
+- Map state updates stop delivering to subscribers removed during the same notification.
+
 - Director assets cancelled during the final stream read are discarded with reader cleanup.
 
 - Analyst queries preserve useful rows when an upstream timestamp is outside the supported date range.

docs/CURRENT-STATE.md

@@ -5224,6 +5224,10 @@ falls back to OSM on construction failure or two active tile failures, and
 credits follow the source actually displayed. Terrain remains lazy while the
 photoreal globe is hidden.
 
+Map-stack subscribers hear each settled activation once. A subscriber removed
+during a delivery, or every subscriber once the controller is destroyed, gets
+no further callback from it, and a destroyed controller accepts no new ones.
+
 Map credentials are passed to each source constructor rather than changing SDK-wide Google or ion defaults.
 
 Bing Aerial and Bing Labels resolve their ion imagery endpoint with the supplied

src/maps/controller.js

@@ -131,7 +131,8 @@ export class MapSourceController {
    * @returns {() => void} Unsubscribe.
    */
   subscribe(listener) {
-    if (typeof listener !== 'function') return () => {};
+    // A destroyed controller never settles again, so it takes no listeners.
+    if (typeof listener !== 'function' || this._destroyed) return () => {};
     this._subscribers.add(listener);
     return () => {
       this._subscribers.delete(listener);
@@ -142,6 +143,8 @@ export class MapSourceController {
     if (this._destroyed || !this._subscribers.size) return;
     const state = this.getState();
     for (const listener of [...this._subscribers]) {
+      if (this._destroyed) return;
+      if (!this._subscribers.has(listener)) continue;
       try {
         listener(state);
       } catch (error) {

src/maps/map-subscription-ownership.test.mjs

@@ -0,0 +1,89 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { MapSourceController } from './controller.js';
+function fixture() {
+  return new MapSourceController(
+    {
+      scene: {
+        globe: { show: true },
+        requestRender() {},
+        frameState: {
+          creditDisplay: { addStaticCredit() {}, removeStaticCredit() {} },
+        },
+        primitives: { add() {}, remove() {} },
+      },
+      imageryLayers: { add() {}, remove() {} },
+    },
+    {
+      registry: {
+        defaultId: 'fixture',
+        sources: [
+          {
+            descriptor: { id: 'fixture', label: 'Fixture', kind: 'imagery' },
+            imagery: async () => ({}),
+          },
+        ],
+      },
+      createImageryLayer: (provider) => ({ provider }),
+    },
+  );
+}
+test('an unsubscribed owner is skipped in the same map settlement delivery', async () => {
+  const controller = fixture();
+  const calls = [];
+  let detach;
+  controller.subscribe(() => {
+    calls.push('first');
+    detach();
+  });
+  detach = controller.subscribe(() => calls.push('detached'));
+  controller.subscribe(() => calls.push('last'));
+  await controller.setStack('fixture');
+  assert.deepEqual(calls, ['first', 'last']);
+  controller.destroy();
+});
+test('destroying the controller during delivery stops remaining listeners', async () => {
+  const controller = fixture();
+  const calls = [];
+  controller.subscribe(() => {
+    calls.push('destroy');
+    controller.destroy();
+  });
+  controller.subscribe(() => calls.push('detached'));
+  await controller.setStack('fixture');
+  assert.deepEqual(calls, ['destroy']);
+});
+
+test('a listener re-added after destroy during delivery is not called', async () => {
+  const controller = fixture();
+  const calls = [];
+  const later = () => calls.push('later');
+  controller.subscribe(() => {
+    calls.push('destroy');
+    controller.destroy();
+    controller.subscribe(later);
+  });
+  controller.subscribe(later);
+  await controller.setStack('fixture');
+  assert.deepEqual(calls, ['destroy']);
+});
+
+test('delivery order: added during delivery waits, duplicates run once, re-added runs', async () => {
+  const controller = fixture();
+  const calls = [];
+  const twice = () => calls.push('twice');
+  const readded = () => calls.push('readded');
+  let offReadded;
+  controller.subscribe(() => {
+    calls.push('first');
+    controller.subscribe(() => calls.push('added-late'));
+    offReadded();
+    controller.subscribe(readded);
+  });
+  controller.subscribe(twice);
+  controller.subscribe(twice);
+  offReadded = controller.subscribe(readded);
+  await controller.setStack('fixture');
+  assert.deepEqual(calls, ['first', 'twice', 'readded']);
+  controller.destroy();
+});