tor-browser

descriptor-mixin.js (2710B)

---

/* 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/. */

"use strict";

/**
* A Descriptor represents a debuggable context. It can be a browser tab, a tab on
* a remote device, like a tab on Firefox for Android. But it can also be an add-on,
* as well as firefox parent process, or just one of its content process.
* It can be very similar to a Target. The key difference is the lifecycle of these two classes.
* The descriptor is meant to be always alive and meaningful/usable until the end of the RDP connection.
* Typically a Tab Descriptor will describe the tab and not the one document currently loaded in this tab,
* while the Target, will describe this one document and a new Target may be created on each navigation.
*/
function DescriptorMixin(parentClass) {
 class Descriptor extends parentClass {
   constructor(client, targetFront, parentFront) {
     super(client, targetFront, parentFront);

     this._client = client;

     // Pass a true value in order to distinguish this event reception
     // from any manual destroy caused by the frontend
     this.on(
       "descriptor-destroyed",
       this.destroy.bind(this, { isServerDestroyEvent: true })
     );
   }

   get client() {
     return this._client;
   }

   async destroy({ isServerDestroyEvent } = {}) {
     if (this.isDestroyed()) {
       return;
     }
     // This workaround is mostly done for Workers, as WorkerDescriptor
     // extends the Target class, which causes some issue down the road:
     // In Target.destroy, we call WorkerDescriptorActor.detach *before* calling super.destroy(),
     // and so hold on before calling Front.destroy() which would reject all pending requests, including detach().
     // When calling detach, the server will emit "descriptor-destroyed", which will call Target.destroy again,
     // but will still be blocked on detach resolution and won't call Front.destroy, and won't reject pending requests either.
     //
     // So call Front.baseFrontClassDestroyed manually from here, so that we ensure rejecting the pending detach request
     // and unblock Target.destroy resolution.
     //
     // Here is the inheritance chain for WorkerDescriptor:
     // WorkerDescriptor -> Descriptor (from descriptor-mixin.js) -> Target (from target-mixin.js) -> Front (protocol.js) -> Pool (protocol.js) -> EventEmitter
     if (isServerDestroyEvent) {
       this.baseFrontClassDestroy();
     }

     await super.destroy();
   }
 }
 return Descriptor;
}
exports.DescriptorMixin = DescriptorMixin;