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Bug 1870957 - Part 2. Allow nsExpirationTracker to be created on any thread. r=gfx-reviewers,lsalzman

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This patch allows us to create nsExpirationTracker objects off the main
thread, with the caveat that memory pressure events should/must be
handled directly by the creator rather than managed internally. With
that in mind, the threading assertions have also been updated to ensure
it is always the owning thread that accesses the tracker.

Differential Revision: https://phabricator.services.mozilla.com/D189527
This commit is contained in:
Andrew Osmond 2023-12-20 13:01:19 +00:00
parent 0837c517ad
commit e5b44ceaaa
1 changed files with 17 additions and 26 deletions
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43
xpcom/ds/nsExpirationTracker.h
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@ -121,28 +121,22 @@ class ExpirationTrackerImpl {
mEventTarget(aEventTarget) {
static_assert(K >= 2 && K <= nsExpirationState::NOT_TRACKED,
"Unsupported number of generations (must be 2 <= K <= 15)");
MOZ_ASSERT(NS_IsMainThread());
if (mEventTarget) {
bool current = false;
// NOTE: The following check+crash could be condensed into a
// MOZ_RELEASE_ASSERT, but that triggers a segfault during compilation in
// clang 3.8. Once we don't have to care about clang 3.8 anymore, though,
// we can convert to MOZ_RELEASE_ASSERT here.
if (MOZ_UNLIKELY(NS_FAILED(mEventTarget->IsOnCurrentThread(&current)) ||
!current)) {
MOZ_CRASH("Provided event target must be on the main thread");
}
// If we are not initialized on the main thread, the owner is responsible
// for dealing with memory pressure events.
if (NS_IsMainThread()) {
mObserver = new ExpirationTrackerObserver();
mObserver->Init(this);
}
mObserver = new ExpirationTrackerObserver();
mObserver->Init(this);
}
virtual ~ExpirationTrackerImpl() {
MOZ_ASSERT(NS_IsMainThread());
if (mTimer) {
mTimer->Cancel();
}
mObserver->Destroy();
if (mObserver) {
MOZ_ASSERT(NS_IsMainThread());
mObserver->Destroy();
}
}
/**
@ -462,17 +456,10 @@ class ExpirationTrackerImpl {
if (mTimer || !mTimerPeriod) {
return NS_OK;
}
nsCOMPtr<nsIEventTarget> target = mEventTarget;
if (!target && !NS_IsMainThread()) {
// TimerCallback should always be run on the main thread to prevent races
// to the destruction of the tracker.
target = do_GetMainThread();
NS_ENSURE_STATE(target);
}
return NS_NewTimerWithFuncCallback(
getter_AddRefs(mTimer), TimerCallback, this, mTimerPeriod,
nsITimer::TYPE_REPEATING_SLACK_LOW_PRIORITY, mName, target);
nsITimer::TYPE_REPEATING_SLACK_LOW_PRIORITY, mName, mEventTarget);
}
};
@ -505,12 +492,12 @@ class nsExpirationTracker
Lock mLock;
AutoLock FakeLock() {
MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread());
NS_ASSERT_OWNINGTHREAD(nsExpirationTracker);
return AutoLock(mLock);
}
Lock& GetMutex() override {
MOZ_DIAGNOSTIC_ASSERT(NS_IsMainThread());
NS_ASSERT_OWNINGTHREAD(nsExpirationTracker);
return mLock;
}
@ -527,6 +514,8 @@ class nsExpirationTracker
void NotifyHandlerEnd() final {}
protected:
NS_DECL_OWNINGTHREAD
virtual void NotifyExpired(T* aObj) = 0;
public:
@ -535,7 +524,9 @@ class nsExpirationTracker
: ::detail::SingleThreadedExpirationTracker<T, K>(aTimerPeriod, aName,
aEventTarget) {}
virtual ~nsExpirationTracker() = default;
virtual ~nsExpirationTracker() {
NS_ASSERT_OWNINGTHREAD(nsExpirationTracker);
}
nsresult AddObject(T* aObj) {
return this->AddObjectLocked(aObj, FakeLock());