fune/toolkit/components/extensions/test/xpcshell/test_ext_contexts_gc.js

"use strict";

const server = createHttpServer();
server.registerDirectory("/data/", do_get_file("data"));

const BASE_URL = `http://localhost:${server.identity.primaryPort}/data`;

// ExtensionContent.jsm needs to know when it's running from xpcshell,
// to use the right timeout for content scripts executed at document_idle.
ExtensionTestUtils.mockAppInfo();

// Each of these tests do the following:
// 1. Load document to create an extension context (instance of BaseContext).
// 2. Get weak reference to that context.
// 3. Unload the document.
// 4. Force GC and check that the weak reference has been invalidated.

async function reloadTopContext(contentPage) {
  await contentPage.spawn(null, async () => {
    let { TestUtils } = ChromeUtils.import(
      "resource://testing-common/TestUtils.jsm"
    );
    let windowNukeObserved = TestUtils.topicObserved("inner-window-nuked");
    info(`Reloading top-level document`);
    this.content.location.reload();
    await windowNukeObserved;
    info(`Reloaded top-level document`);
  });
}

async function assertContextReleased(contentPage, description) {
  await contentPage.spawn(description, async assertionDescription => {
    // Force GC, see https://searchfox.org/mozilla-central/rev/b0275bc977ad7fda615ef34b822bba938f2b16fd/testing/talos/talos/tests/devtools/addon/content/damp.js#84-98
    // and https://searchfox.org/mozilla-central/rev/33c21c060b7f3a52477a73d06ebcb2bf313c4431/xpcom/base/nsMemoryReporterManager.cpp#2574-2585,2591-2594
    let gcCount = 0;
    while (gcCount < 30 && this.contextWeakRef.get() !== null) {
      ++gcCount;
      // The JS engine will sometimes hold IC stubs for function
      // environments alive across multiple CCs, which can keep
      // closed-over JS objects alive. A shrinking GC will throw those
      // stubs away, and therefore side-step the problem.
      Cu.forceShrinkingGC();
      Cu.forceCC();
      Cu.forceGC();
      await new Promise(resolve => this.content.setTimeout(resolve, 0));
    }

    // The above loop needs to be repeated at most 3 times according to MinimizeMemoryUsage:
    // https://searchfox.org/mozilla-central/rev/6f86cc3479f80ace97f62634e2c82a483d1ede40/xpcom/base/nsMemoryReporterManager.cpp#2644-2647
    Assert.lessOrEqual(
      gcCount,
      3,
      `Context should have been GCd within a few GC attempts.`
    );

    // Each test will set this.contextWeakRef before unloading the document.
    Assert.ok(!this.contextWeakRef.get(), assertionDescription);
  });
}

add_task(async function test_ContentScriptContextChild_in_child_frame() {
  let extensionData = {
    manifest: {
      content_scripts: [
        {
          matches: ["http://*/*/file_iframe.html"],
          js: ["content_script.js"],
          all_frames: true,
        },
      ],
    },

    files: {
      "content_script.js": "browser.test.sendMessage('contentScriptLoaded');",
    },
  };

  let extension = ExtensionTestUtils.loadExtension(extensionData);
  await extension.startup();

  let contentPage = await ExtensionTestUtils.loadContentPage(
    `${BASE_URL}/file_toplevel.html`
  );
  await extension.awaitMessage("contentScriptLoaded");

  await contentPage.spawn(extension.id, async extensionId => {
    const { ExtensionContent } = ChromeUtils.import(
      "resource://gre/modules/ExtensionContent.jsm"
    );
    let frame = this.content.document.querySelector(
      "iframe[src*='file_iframe.html']"
    );
    let context = ExtensionContent.getContextByExtensionId(
      extensionId,
      frame.contentWindow
    );

    Assert.ok(!!context, "Got content script context");

    this.contextWeakRef = Cu.getWeakReference(context);
    frame.remove();
  });

  await assertContextReleased(
    contentPage,
    "ContentScriptContextChild should have been released"
  );

  await contentPage.close();
  await extension.unload();
});

add_task(async function test_ContentScriptContextChild_in_toplevel() {
  let extensionData = {
    manifest: {
      content_scripts: [
        {
          matches: ["http://*/*/file_sample.html"],
          js: ["content_script.js"],
          all_frames: true,
        },
      ],
    },

    files: {
      "content_script.js": "browser.test.sendMessage('contentScriptLoaded');",
    },
  };

  let extension = ExtensionTestUtils.loadExtension(extensionData);
  await extension.startup();

  let contentPage = await ExtensionTestUtils.loadContentPage(
    `${BASE_URL}/file_sample.html`
  );
  await extension.awaitMessage("contentScriptLoaded");

  await contentPage.spawn(extension.id, async extensionId => {
    const { ExtensionContent } = ChromeUtils.import(
      "resource://gre/modules/ExtensionContent.jsm"
    );
    let context = ExtensionContent.getContextByExtensionId(
      extensionId,
      this.content
    );

    Assert.ok(!!context, "Got content script context");

    this.contextWeakRef = Cu.getWeakReference(context);
  });

  await reloadTopContext(contentPage);
  await extension.awaitMessage("contentScriptLoaded");
  await assertContextReleased(
    contentPage,
    "ContentScriptContextChild should have been released"
  );

  await contentPage.close();
  await extension.unload();
});

add_task(async function test_ExtensionPageContextChild_in_child_frame() {
  let extensionData = {
    files: {
      "iframe.html": `
        <!DOCTYPE html><meta charset="utf8">
        <script src="script.js"></script>
      `,
      "toplevel.html": `
        <!DOCTYPE html><meta charset="utf8">
        <iframe src="iframe.html"></iframe>
      `,
      "script.js": "browser.test.sendMessage('extensionPageLoaded');",
    },
  };

  let extension = ExtensionTestUtils.loadExtension(extensionData);
  await extension.startup();

  let contentPage = await ExtensionTestUtils.loadContentPage(
    `moz-extension://${extension.uuid}/toplevel.html`,
    {
      extension,
      remote: extension.extension.remote,
    }
  );
  await extension.awaitMessage("extensionPageLoaded");

  await contentPage.spawn(extension.id, async extensionId => {
    let { ExtensionPageChild } = ChromeUtils.import(
      "resource://gre/modules/ExtensionPageChild.jsm"
    );

    let frame = this.content.document.querySelector(
      "iframe[src*='iframe.html']"
    );
    let innerWindowID =
      frame.browsingContext.currentWindowContext.innerWindowId;
    let context = ExtensionPageChild.extensionContexts.get(innerWindowID);

    Assert.ok(!!context, "Got extension page context for child frame");

    this.contextWeakRef = Cu.getWeakReference(context);
    frame.remove();
  });

  await assertContextReleased(
    contentPage,
    "ExtensionPageContextChild should have been released"
  );

  await contentPage.close();
  await extension.unload();
});

add_task(async function test_ExtensionPageContextChild_in_toplevel() {
  let extensionData = {
    files: {
      "toplevel.html": `
        <!DOCTYPE html><meta charset="utf8">
        <script src="script.js"></script>
      `,
      "script.js": "browser.test.sendMessage('extensionPageLoaded');",
    },
  };

  let extension = ExtensionTestUtils.loadExtension(extensionData);
  await extension.startup();

  let contentPage = await ExtensionTestUtils.loadContentPage(
    `moz-extension://${extension.uuid}/toplevel.html`,
    {
      extension,
      remote: extension.extension.remote,
    }
  );
  await extension.awaitMessage("extensionPageLoaded");

  await contentPage.spawn(extension.id, async extensionId => {
    let { ExtensionPageChild } = ChromeUtils.import(
      "resource://gre/modules/ExtensionPageChild.jsm"
    );

    let innerWindowID = this.content.windowGlobalChild.innerWindowId;
    let context = ExtensionPageChild.extensionContexts.get(innerWindowID);

    Assert.ok(!!context, "Got extension page context for top-level document");

    this.contextWeakRef = Cu.getWeakReference(context);
  });

  await reloadTopContext(contentPage);
  await extension.awaitMessage("extensionPageLoaded");
  // For some unknown reason, the context cannot forcidbly be released by the
  // garbage collector unless we wait for a short while.
  await contentPage.spawn(null, async () => {
    let start = Date.now();
    // The treshold was found after running this subtest only, 300 times
    // in a release build (100 of xpcshell, xpcshell-e10s and xpcshell-remote).
    // With treshold 8, almost half of the tests complete after a 17-18 ms delay.
    // With treshold 7, over half of the tests complete after a 13-14 ms delay,
    //  with 12 failures in 300 tests runs.
    // Let's double that number to have a safety margin.
    for (let i = 0; i < 15; ++i) {
      await new Promise(resolve => this.content.setTimeout(resolve, 0));
    }
    info(`Going to GC after waiting for ${Date.now() - start} ms.`);
  });
  await assertContextReleased(
    contentPage,
    "ExtensionPageContextChild should have been released"
  );

  await contentPage.close();
  await extension.unload();
});