Release the cockpit cloud WebGL context when its controller is destroyed

src/cockpitCloudEffects.js

@@ -199,6 +199,7 @@ class CockpitCloudEffectsController {
 
     this.gl = null;
     this.program = null;
+    this.buffer = null;
     this.locations = null;
     this.frame = null;
     this.refreshTimer = null;
@@ -275,8 +276,9 @@ class CockpitCloudEffectsController {
   }
 
   initializeRenderer() {
+    let gl = null;
     try {
-      const gl = this.canvas.getContext('webgl', {
+      gl = this.canvas.getContext('webgl', {
         alpha: true,
         antialias: false,
         depth: false,
@@ -318,6 +320,7 @@ class CockpitCloudEffectsController {
 
       this.gl = gl;
       this.program = program;
+      this.buffer = buffer;
       this.locations = {
         resolution: gl.getUniformLocation(program, 'uResolution'),
         time: gl.getUniformLocation(program, 'uTime'),
@@ -327,6 +330,7 @@ class CockpitCloudEffectsController {
     } catch (error) {
       console.warn('[Cockpit clouds] Renderer unavailable:', error);
       this.canvas.dataset.status = 'unavailable';
+      if (gl && !this.gl) gl.getExtension('WEBGL_lose_context')?.loseContext();
     }
   }
 
@@ -605,9 +609,26 @@ class CockpitCloudEffectsController {
       'gev:cockpit-weather-toggle',
       this.onEnabledChange,
     );
-    if (this.program && this.gl) this.gl.deleteProgram(this.program);
+    this.releaseRenderer();
     this.canvas.remove();
   }
+
+  /**
+   * Free the GPU objects and the canvas's WebGL context. The application is
+   * rebuilt on every globe switch, and browsers cap live contexts, so a
+   * destroyed controller must not leave its context for garbage collection.
+   */
+  releaseRenderer() {
+    const gl = this.gl;
+    this.gl = null;
+    this.locations = null;
+    if (!gl) return;
+    if (this.buffer) gl.deleteBuffer(this.buffer);
+    if (this.program) gl.deleteProgram(this.program);
+    this.buffer = null;
+    this.program = null;
+    gl.getExtension('WEBGL_lose_context')?.loseContext();
+  }
 }
 
 export function initCockpitCloudEffects(viewer, options) {

src/cockpitCloudEffects.test.mjs

@@ -1,19 +1,32 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
 import {
+  initCockpitCloudEffects,
   cockpitCloudRenderSize,
   cockpitWeatherRefreshDue,
   cockpitWeatherEnabledFromStoredValue,
 } from './cockpitCloudEffects.js';
 
 test('cockpit cloud framebuffer stays low resolution on large displays', () => {
-  assert.deepEqual(cockpitCloudRenderSize(2048, 1152), { width: 520, height: 293 });
-  assert.deepEqual(cockpitCloudRenderSize(1280, 720), { width: 520, height: 293 });
+  assert.deepEqual(cockpitCloudRenderSize(2048, 1152), {
+    width: 520,
+    height: 293,
+  });
+  assert.deepEqual(cockpitCloudRenderSize(1280, 720), {
+    width: 520,
+    height: 293,
+  });
 });
 
 test('cockpit cloud framebuffer never upscales or collapses to zero', () => {
-  assert.deepEqual(cockpitCloudRenderSize(640, 360), { width: 269, height: 151 });
-  assert.deepEqual(cockpitCloudRenderSize(0, Number.NaN), { width: 1, height: 1 });
+  assert.deepEqual(cockpitCloudRenderSize(640, 360), {
+    width: 269,
+    height: 151,
+  });
+  assert.deepEqual(cockpitCloudRenderSize(0, Number.NaN), {
+    width: 1,
+    height: 1,
+  });
 });
 
 test('cockpit weather defaults off and enables only from an explicit saved opt-in', () => {
@@ -25,32 +38,163 @@ test('cockpit weather defaults off and enables only from an explicit saved opt-i
 
 test('cockpit weather refreshes after time or meaningful movement', () => {
   const anchor = { latitude: 30, longitude: -97 };
-  assert.equal(cockpitWeatherRefreshDue({
-    nowMs: 1000,
-    fetchedAt: 500,
-    anchor,
-    point: anchor,
-    hasWeather: false,
-  }), true);
-  assert.equal(cockpitWeatherRefreshDue({
-    nowMs: 60_000,
-    fetchedAt: 0,
-    anchor,
-    point: { latitude: 30.01, longitude: -97 },
-    hasWeather: true,
-  }), false);
-  assert.equal(cockpitWeatherRefreshDue({
-    nowMs: 5 * 60_000,
-    fetchedAt: 0,
-    anchor,
-    point: anchor,
-    hasWeather: true,
-  }), true);
-  assert.equal(cockpitWeatherRefreshDue({
-    nowMs: 60_000,
-    fetchedAt: 0,
-    anchor,
-    point: { latitude: 30.3, longitude: -97 },
-    hasWeather: true,
-  }), true);
+  assert.equal(
+    cockpitWeatherRefreshDue({
+      nowMs: 1000,
+      fetchedAt: 500,
+      anchor,
+      point: anchor,
+      hasWeather: false,
+    }),
+    true,
+  );
+  assert.equal(
+    cockpitWeatherRefreshDue({
+      nowMs: 60_000,
+      fetchedAt: 0,
+      anchor,
+      point: { latitude: 30.01, longitude: -97 },
+      hasWeather: true,
+    }),
+    false,
+  );
+  assert.equal(
+    cockpitWeatherRefreshDue({
+      nowMs: 5 * 60_000,
+      fetchedAt: 0,
+      anchor,
+      point: anchor,
+      hasWeather: true,
+    }),
+    true,
+  );
+  assert.equal(
+    cockpitWeatherRefreshDue({
+      nowMs: 60_000,
+      fetchedAt: 0,
+      anchor,
+      point: { latitude: 30.3, longitude: -97 },
+      hasWeather: true,
+    }),
+    true,
+  );
+});
+
+// A WebGL context that records what is allocated, freed and lost.
+function fakeWebGl() {
+  const calls = [];
+  const gl = {
+    VERTEX_SHADER: 1,
+    FRAGMENT_SHADER: 2,
+    ARRAY_BUFFER: 3,
+    STATIC_DRAW: 4,
+    FLOAT: 5,
+    COLOR_BUFFER_BIT: 6,
+    LINK_STATUS: 7,
+    COMPILE_STATUS: 8,
+    calls,
+    createShader: () => ({}),
+    shaderSource() {},
+    compileShader() {},
+    getShaderParameter: () => true,
+    getShaderInfoLog: () => '',
+    deleteShader() {},
+    createProgram: () => ({ program: true }),
+    attachShader() {},
+    linkProgram() {},
+    getProgramParameter: () => true,
+    getProgramInfoLog: () => '',
+    deleteProgram: (program) => calls.push(['deleteProgram', program]),
+    createBuffer: () => ({ buffer: true }),
+    bindBuffer() {},
+    bufferData() {},
+    deleteBuffer: (buffer) => calls.push(['deleteBuffer', buffer]),
+    getAttribLocation: () => 0,
+    enableVertexAttribArray() {},
+    vertexAttribPointer() {},
+    getUniformLocation: () => ({}),
+    viewport() {},
+    clearColor() {},
+    clear() {},
+    getExtension: (name) =>
+      name === 'WEBGL_lose_context'
+        ? { loseContext: () => calls.push(['loseContext']) }
+        : null,
+  };
+  return gl;
+}
+
+test('a destroyed cockpit cloud controller frees its GPU objects and WebGL context', () => {
+  const saved = Object.fromEntries(
+    [
+      'document',
+      'window',
+      'localStorage',
+      'CustomEvent',
+      'requestAnimationFrame',
+      'cancelAnimationFrame',
+    ].map((name) => [name, globalThis[name]]),
+  );
+  const gl = fakeWebGl();
+  let contexts = 0;
+  const canvas = {
+    dataset: {},
+    classList: { add() {}, remove() {} },
+    setAttribute() {},
+    remove() {
+      canvas.removed = true;
+    },
+    getContext() {
+      contexts += 1;
+      return gl;
+    },
+  };
+  globalThis.document = {
+    createElement: () => canvas,
+    body: { appendChild() {}, classList: { contains: () => true } },
+  };
+  globalThis.window = {
+    innerWidth: 1280,
+    innerHeight: 720,
+    matchMedia: () => ({ matches: false }),
+    addEventListener() {},
+    removeEventListener() {},
+    dispatchEvent() {},
+    setTimeout: () => 1,
+    clearTimeout() {},
+  };
+  globalThis.localStorage = { getItem: () => '1', setItem() {} };
+  globalThis.CustomEvent = class {
+    constructor(type, init) {
+      this.type = type;
+      this.detail = init?.detail;
+    }
+  };
+  globalThis.requestAnimationFrame = () => 7;
+  globalThis.cancelAnimationFrame = () => {};
+  try {
+    const clouds = initCockpitCloudEffects(null, { weatherService: {} });
+    clouds.start();
+    clouds.stop();
+    clouds.start();
+    assert.equal(
+      contexts,
+      1,
+      'one context per controller, reused across starts',
+    );
+    const { program, buffer } = clouds;
+    clouds.destroy();
+    assert.deepEqual(gl.calls, [
+      ['deleteBuffer', buffer],
+      ['deleteProgram', program],
+      ['loseContext'],
+    ]);
+    assert.equal(clouds.gl, null);
+    assert.equal(canvas.removed, true);
+  } finally {
+    for (const [name, value] of Object.entries(saved)) {
+      if (value === undefined) delete globalThis[name];
+      else globalThis[name] = value;
+    }
+  }
 });