smayya
109b38c95b
Implements "wait for a matching prefetch record": when navigation arrives while a potentially matching prefetch is still ongoing, WaitForMatchingPrefetchRecord fast-paths to FindMatchingPrefetchRecord (sync), or registers a PrefetchMatchWaiter if ongoing records could satisfy the URL. PrefetchMatchWaiter holds a MozPromise, an nsITimer for the dom.speculation_rules.wait_timeout_ms timeout, and an Atomic<bool> resolved flag to prevent double-resolution if the timer and a state-change notification race. NotifyPrefetchStateChanged now iterates mPrefetchWaiters and calls OnRecordStateChanged on each. Spec: https://wicg.github.io/nav-speculation/prefetch.html#wait-for-a-matching-prefetch-record Differential Revision: https://phabricator.services.mozilla.com/D302513
95 lines
3.2 KiB
C++
95 lines
3.2 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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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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#include "mozilla/dom/PrefetchMatchWaiter.h"
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#include "mozilla/dom/PrefetchLog.h"
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#include "mozilla/dom/PrefetchRecordParent.h"
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#include "mozilla/dom/WindowGlobalParent.h"
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namespace mozilla::dom {
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PrefetchMatchWaiter::PrefetchMatchWaiter(WindowGlobalParent* aWGP, nsIURI* aURI,
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TimeDuration aTimeout)
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: mWGP(aWGP), mURI(aURI) {
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LOG_SPECRULES((
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"PrefetchMatchWaiter ctor: this=%p url=%s timeout=%.0fms", this,
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[&] {
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nsAutoCString s;
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if (aURI) {
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aURI->GetSpec(s);
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}
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return s;
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}()
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.get(),
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aTimeout.ToMilliseconds()));
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}
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already_AddRefed<PrefetchMatchWaiter> PrefetchMatchWaiter::Create(
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WindowGlobalParent* aWGP, nsIURI* aURI, TimeDuration aTimeout) {
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RefPtr<PrefetchMatchWaiter> self =
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new PrefetchMatchWaiter(aWGP, aURI, aTimeout);
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NS_NewTimerWithCallback(
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getter_AddRefs(self->mTimer),
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[self](nsITimer*) {
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LOG_SPECRULES(("PrefetchMatchWaiter::OnTimeout: this=%p", self.get()));
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self->Resolve(nullptr);
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},
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static_cast<uint32_t>(aTimeout.ToMilliseconds()), nsITimer::TYPE_ONE_SHOT,
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"PrefetchMatchWaiter"_ns);
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return self.forget();
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}
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void PrefetchMatchWaiter::OnRecordStateChanged(PrefetchRecordParent* aRec) {
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// Implements the "wait until the state of any element ... changes" step
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// of "wait for a matching prefetch record": re-run the loop body once for
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// the record whose state just changed.
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// Spec:
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// https://wicg.github.io/nav-speculation/prefetch.html#wait-for-a-matching-prefetch-record
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if (mResolved) {
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return;
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}
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// aRec is the record that changed; if it's not the one that unblocked us,
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// re-checking is still correct but wasted work, so bail out early unless
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// aRec itself could be relevant to mURI.
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if (aRec && aRec->State() != PrefetchState::Completed &&
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!aRec->IsExpectedToMatch(mURI)) {
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return;
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}
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if (PrefetchRecordParent* match = mWGP->FindMatchingPrefetchRecord(mURI)) {
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LOG_SPECRULES(
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("PrefetchMatchWaiter::OnRecordStateChanged: this=%p found match=%p",
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this, match));
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Resolve(match);
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return;
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}
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// "If potentialRecords is empty, return null": give up as soon as no
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// ongoing record could still satisfy this navigation, instead of waiting
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// for aTimeout.
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if (!mWGP->HasPotentialPrefetchMatch(mURI)) {
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LOG_SPECRULES(
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("PrefetchMatchWaiter::OnRecordStateChanged: this=%p no potential "
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"match remains, resolving nullptr",
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this));
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Resolve(nullptr);
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}
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}
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void PrefetchMatchWaiter::Resolve(PrefetchRecordParent* aMatch) {
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if (mResolved.exchange(true)) {
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return; // already resolved — idempotent
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}
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if (mTimer) {
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mTimer->Cancel();
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mTimer = nullptr;
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}
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LOG_SPECRULES(
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("PrefetchMatchWaiter::Resolve: this=%p match=%p", this, aMatch));
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mPromiseHolder.ResolveIfExists(RefPtr{aMatch}, __func__);
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mWGP->RemoveWaiter(this);
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}
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} // namespace mozilla::dom
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