js.Origin was added to allow frames on the same origin to share our zig<->js
maps / identity. It assumes that scripts on different origins will never be
allowed (by v8) to access the same zig instances.
If two different origins DID access the same zig instance, we'd have a few
different problems. First, while the mapping would exist in Origin1's
identity_map, when the zig instance was returned to a script in Origin2, it
would not be found in Origin2's identity_map, and thus create a new v8::Object.
Thus we'd end up with 2 v8::Objects for the same Zig instance. This is
potentially not the end of the world, but not great either as any zig-native
data _would_ be shared (it's the same instance after all), but js-native data
wouldn't.
The real problem this introduces though is with Finalizers. A weak reference
that falls out of scope in Origin1 will get cleaned up, even though it's still
referenced from Origin2.
Now, under normal circumstances, this isn't an issue; v8 _does_ ensure that
cross-origin access isn't allowed (because we set a SecurityToken on the
v8::Context). But it seems like the v8::Inspector isn't bound by these
restrictions and can happily access and share objects across origin.
The simplest solution I can come up with is to move the mapping from the Origin
to the Session. This does mean that objects might live longer than they have to.
When all references to an origin go out of scope, we can do some cleanup. Not
so when the Session owns this data. But really, how often are iframes on
different origins being created and deleted within the lifetime of a page?
When Origins were first introduces, the Session got burdened with having to
manage multiple lifecycles:
1 - The page-surviving data (e.g. history)
2 - The root page lifecycle (e.g. page_arena, queuedNavigation)
3 - The origin lookup
This commit doesn't change that, but it makes the session responsible for
_a lot_ more of the root page lifecycle (#2 above).
I lied. js.Origin still exists, but it's a shell of its former self. It only
exists to store the SecurityToken name that is re-used for every context with
the same origin.
The v8 namespace leaks into Session.
MutationObserver and IntersectionObserver are now back to using weak/strong refs
which was one of the failing cases before this change.
In the first iteration of this, we kept an ArrayList of all rules with
visibility properties. Why bother evaluating if a rule's selector matches an
element if that rule doesn't have any meanignful (i.e. visibility) properties?
This commit enhances that approach by bucketing the rules. Given the following
selectors:
.hidden {....}
.footer > .small {...}
We can store the rules based on their right-most selector. So, given an element
we can do:
if (getId(el)) |id| {
const rules = id_lookup.get(id) orelse continue;
// check rules
}
if (getClasses(el)) |classes| {
for (classes) |c| {
const rules = class_lookup(c) orelse continue;
// chck rules
}
}
...
On an amazon product page, the total list of visibility-related rules was ~230.
Now, scanning 230 rules for a match isn't _aweful_, but remember that this has
to be done up the ancestor tree AND, for Amazon, this is called over 20K times.
This change requires that the StyleManager becomes more matching/parsing-aware
but a typical visibility check on that same Amazon product page only has to
check 2 rules (down from 230) and often has to check 0 rules.
Also, we now filter out a few more interactive-related pseudo-elements, e.g.
:hover. These aren't supported by the browser as a whole (i.e. they can _never_
match), so they can be filtered out early, when building the rules lookup.
We now pay attention to the type of event that causes the unhandled exception.
This allows us to trigger the window.rejectionhandled event when that is the
correct type. It also lets us no-op for other event types which should not
trigger rejectionhandled or unhandledrejection.
Fixes stackoverflow in github integration.
- Refactor `wait` and `_wait` to handle `page` as `*Page` instead of `**Page`, preventing stale references during navigations.
- Update `networkidle` wait condition to use `_notified_network_idle == .done`.
- Document `--wait_ms` and `--wait_until` options in `Config.zig` help text.
A Page now has a StyleManager. The StyleManager currently answers two questions:
1 - Is an element hidden
2 - Does an element have pointer-events == none
This is used in calls such as element.checkVisibility which, on some pages, can
be called tens of thousands of times (often through other methods, like
element.getBoundingClientRect). This _can_ be a bottleneck.
The StyleManager keeps a list of rules. The rules include the selector,
specificity, and properties that we care about. Rules in a stylesheet that
contain no properties of interest are ignored. This is the first and likely
most significant optimization. Presumably, most CSS rules don't have a
display/visibility/opacity or pointer-events property.
The list is rules is cached until stylesheets are modified or delete. When this
happens, the StyleManager is flagged as "dirty" and rebuilt on-demand in the
next query. This is our second major optimization.
For now, to check if an element is visible, we still need to scan all rules.
But having a pre-build subset of all the rules is a first step.
The next step might be to optimize the matching, or possibly optimizing common
cases (e.g. id and/or simple class selector)
Add `--wait_until` and `--wait_ms` CLI arguments to configure session wait behavior. Updates `Session.wait` to evaluate specific page load states (`load`, `domcontentloaded`, `networkidle`, `fixed`) before completing the wait loop.
