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/* 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/. */
const lazy = {};
ChromeUtils.defineESModuleGetters(lazy, {
HiddenFrame: "resource://gre/modules/HiddenFrame.sys.mjs",
});
/**
* @typedef {import("../actors/MLEngineParent.sys.mjs").MLEngineParent} MLEngineParent
*/
/**
* @typedef {import("../../translations/actors/TranslationsEngineParent.sys.mjs").TranslationsEngineParent} TranslationsEngineParent
*/
/**
* This class controls the life cycle of the engine process used both in the
* Translations engine and the MLEngine component.
*/
export class EngineProcess {
/**
* @type {Promise<{ hiddenFrame: HiddenFrame, actor: TranslationsEngineParent }> | null}
*/
/** @type {Promise<HiddenFrame> | null} */
static #hiddenFrame = null;
/** @type {Promise<TranslationsEngineParent> | null} */
static translationsEngineParent = null;
/** @type {Promise<MLEngineParent> | null} */
static mlEngineParent = null;
/** @type {((actor: TranslationsEngineParent) => void) | null} */
resolveTranslationsEngineParent = null;
/** @type {((actor: MLEngineParent) => void) | null} */
resolveMLEngineParent = null;
/**
* See if all engines are terminated. This is useful for testing.
*
* @returns {boolean}
*/
static areAllEnginesTerminated() {
return (
!EngineProcess.#hiddenFrame &&
!EngineProcess.translationsEngineParent &&
!EngineProcess.mlEngineParent
);
}
/**
* @returns {Promise<TranslationsEngineParent>}
*/
static async getTranslationsEngineParent() {
if (!this.translationsEngineParent) {
this.translationsEngineParent = this.#attachBrowser({
id: "translations-engine-browser",
url: "chrome://global/content/translations/translations-engine.html",
resolverName: "resolveTranslationsEngineParent",
});
}
return this.translationsEngineParent;
}
/**
* @returns {Promise<MLEngineParent>}
*/
static async getMLEngineParent() {
if (!this.mlEngineParent) {
this.mlEngineParent = this.#attachBrowser({
id: "ml-engine-browser",
url: "chrome://global/content/ml/MLEngine.html",
resolverName: "resolveMLEngineParent",
});
}
return this.mlEngineParent;
}
/**
* @param {object} config
* @param {string} config.url
* @param {string} config.id
* @param {string} config.resolverName
* @returns {Promise<TranslationsEngineParent>}
*/
static async #attachBrowser({ url, id, resolverName }) {
const hiddenFrame = await this.#getHiddenFrame();
const chromeWindow = await hiddenFrame.get();
const doc = chromeWindow.document;
if (doc.getElementById(id)) {
throw new Error(
"Attempting to append the translations-engine.html <browser> when one " +
"already exists."
);
}
const browser = doc.createXULElement("browser");
browser.setAttribute("id", id);
browser.setAttribute("remote", "true");
browser.setAttribute("remoteType", "web");
browser.setAttribute("disableglobalhistory", "true");
browser.setAttribute("type", "content");
browser.setAttribute("src", url);
ChromeUtils.addProfilerMarker(
"EngineProcess",
{},
`Creating the "${id}" process`
);
doc.documentElement.appendChild(browser);
const { promise, resolve } = Promise.withResolvers();
// The engine parents must resolve themselves when they are ready.
this[resolverName] = resolve;
return promise;
}
/**
* @returns {HiddenFrame}
*/
static async #getHiddenFrame() {
if (!EngineProcess.#hiddenFrame) {
EngineProcess.#hiddenFrame = new lazy.HiddenFrame();
}
return EngineProcess.#hiddenFrame;
}
/**
* Destroy the translations engine, and remove the hidden frame if no other
* engines exist.
*/
static destroyTranslationsEngine() {
return this.#destroyEngine({
id: "translations-engine-browser",
keyName: "translationsEngineParent",
});
}
/**
* Destroy the ML engine, and remove the hidden frame if no other engines exist.
*/
static destroyMLEngine() {
return this.#destroyEngine({
id: "ml-engine-browser",
keyName: "mlEngineParent",
});
}
/**
* Destroy the specified engine and maybe the entire hidden frame as well if no engines
* are remaining.
*/
static #destroyEngine({ id, keyName }) {
ChromeUtils.addProfilerMarker(
"EngineProcess",
{},
`Destroying the "${id}" engine`
);
const actorShutdown = this.forceActorShutdown(id, keyName).catch(
error => void console.error(error)
);
this[keyName] = null;
const hiddenFrame = EngineProcess.#hiddenFrame;
if (hiddenFrame && !this.translationsEngineParent && !this.mlEngineParent) {
EngineProcess.#hiddenFrame = null;
// Both actors are destroyed, also destroy the hidden frame.
actorShutdown.then(() => {
// Double check a race condition that no new actors have been created during
// shutdown.
if (this.translationsEngineParent && this.mlEngineParent) {
return;
}
if (!hiddenFrame) {
return;
}
hiddenFrame.destroy();
ChromeUtils.addProfilerMarker(
"EngineProcess",
{},
`Removing the hidden frame`
);
});
}
// Infallibly resolve the promise even if there are errors.
return Promise.resolve();
}
/**
* Shut down an actor and remove its <browser> element.
*
* @param {string} id
* @param {string} keyName
*/
static async forceActorShutdown(id, keyName) {
const actorPromise = this[keyName];
if (!actorPromise) {
return;
}
let actor;
try {
actor = await actorPromise;
} catch {
// The actor failed to initialize, so it doesn't need to be shut down.
return;
}
// Shut down the actor.
try {
await actor.forceShutdown();
} catch (error) {
console.error("Failed to shut down the actor " + id, error);
return;
}
if (!EngineProcess.#hiddenFrame) {
// The hidden frame was already removed.
return;
}
// Remove the <brower> element.
const chromeWindow = EngineProcess.#hiddenFrame.getWindow();
const doc = chromeWindow.document;
const element = doc.getElementById(id);
if (!element) {
console.error("Could not find the <browser> element for " + id);
return;
}
element.remove();
}
}
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