forked from mirrors/gecko-dev
9cdfde0a5e
The service worker job queue can get stuck sometimes, so we don't want the per-process service worker data structure to hold strong references to content. Instead, I add a proxy that is only a weak reference. The wrinkle is that we need to keep the promise alive as long as the job and the window are otherwise alive. I solve this by putting a cycle collected reference to the promise on the window itself. MozReview-Commit-ID: GbmCY4ZIQWk --HG-- extra : rebase_source : 363ea865fd51bb44f3e727cd3469e316370e7cbc
57 lines
1.8 KiB
C++
57 lines
1.8 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef mozilla_dom_PromiseWindowProxy_h
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#define mozilla_dom_PromiseWindowProxy_h
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#include "nsCOMPtr.h"
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#include "mozilla/WeakPtr.h"
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class nsIWeakReference;
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class nsPIDOMWindowInner;
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namespace mozilla {
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namespace dom {
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class Promise;
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// When a data structure is waiting to resolve a promise from a
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// window, but that data structure is not owned by that window, there
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// exists a dilemma:
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//
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// 1) If the promise is never resolved, and the non-window data
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// structure is keeping alive the promise, the promise's window will
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// be leaked.
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//
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// 2) Something has to keep the promise alive from native code in case
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// script has dropped all direct references to it, but the promise is
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// later resolved.
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//
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// PromiseWindowProxy solves this dilemma for the non-window data
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// structure. It solves (1) by only keeping a weak reference to the
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// promise. It solves (2) by adding a strong reference to the promise
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// on the window itself. This ensures that as long as both the
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// PromiseWindowProxy and the window are still alive that the promise
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// will remain alive. This strong reference is cycle collected, so it
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// won't cause the window to leak.
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class PromiseWindowProxy final
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{
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public:
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PromiseWindowProxy(nsPIDOMWindowInner* aWindow, mozilla::dom::Promise* aPromise);
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~PromiseWindowProxy();
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RefPtr<Promise> Get() const;
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nsCOMPtr<nsPIDOMWindowInner> GetWindow() const;
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private:
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nsCOMPtr<nsIWeakReference> mWindow;
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WeakPtr<Promise> mPromise;
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};
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} // namespace dom
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} // namespace mozilla
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#endif // mozilla_dom_PromiseWindowProxy_h
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