Inspector has weak references to v8::Context, if we deinit the inspector and
then shutdown contexts, we risk getting a use-after-free as those weak reference
callback their finalizers on an inspector which no longer exists.
To some degree, this means the Inspector doesn't clean up its weak references
on shutdown. I assume this is because it expects us to always clean them up with
destroyContext.
This also keeps the inspector around until AFTER the page is killed (thus it's
still alive to get the finalizer callback) and moves it off the session arena
onto the browser context itself.
In some cases, it's straightforward to know whether or not there's an implicit
local scope available. But both Navigation and ReadableStream* have more complex
flows. Both could, in theory, be initiated from non-V8 calls, so relying on
the implicit scope isn't safe.
This adds an explicit scope to most callbacks in Navigation and ReadbleStream*.
However, I still don't quite understand how / if these are being initiated from
Zig currently (I could see how they would be, in the future). Therefore, in
debug mode, this will still panic if there's no implicit scope, because I want
to understand what's going on.
We currently force-write a simple HTML doctype for HTMLDocument. But if the
document already has a doctype, that results in us writing the forced one then
writing the correct one. This adds a check and only force-writes a doctype if
the first child of the document isn't a document_type node.
Was added here 43805ad698
But causes segfaults. The issue is hard to understand. At first, it seemed like
the value cached in a v8::Object was persisting through v8::contexts of the
same isolate. Set window.document to the current &document, and in a different
context, it retrieves that cached value (which is now an invalid pointers).
However, upon further investigation, this appears to be limited to a mix of
navigation (which causes a new context to be created, and old values to be
invalidated) + Inspector which continues to send commands to the old context.
Since contextDestroyed is something we're aware of and planning to do shortly,
I think we can disable the cache until that's fixed.
Mem 28MB -> 26MB (currently a 24.1MB)
Time 23 -> 17 (currently at 14)
We've made some memory and performance optimization gains lately. Lowering
these will let us spot incremental changes better.
The idea is that frequently accessed properties, e.g. window.document, can be
cached directly as data properties on the underlying v8::Object, removing the
need for the access call into Zig. This is only used on a handful of properties,
almost all of which are on the Window. It is important that the property be
read-only. For example, window.location cannot be cached this way because
window.location is writable (e.g. window.location.hash = '#blah').
This existed briefly before Zigdom, but was removed as part of the migration.
The implementation has changed. This previously relied on a "postAttach" feature
which no longer exists. It is not integrated in the bridge/callback directly and
lazily applied after the first access.
Previously, we were doing some global setup in the Snapshot, but this was
always being overwritten when creating a context. This meaningless setup in
the snapshot was removed.
The global setup is now done once per isolate, rather than once per context.
