Takes https://github.com/lightpanda-io/browser/pull/2024 a step further and
changes all reference counting to be explicit.
Up until this point, finalizers_callback was seen as a fail-safe to make sure
that instances were released no matter what. It exists because v8 might never
call a finalizer, so we need to keep track of finalizables and finalize them
on behalf of v8. BUT, it was used as more than a fallback for v8...it allowed
us to be lazy and acquireRef's in Zig without a matching releaseRef (1), because
why not, the finalizer_callback will handle it.
This commit redefines finalizer_callbacks as strictly being a fallback for v8.
If v8 calls the finalizer, then the finalizer callback is removed (2) - we lose
our fail-safe. This means that every acquireRef must be matched with a
releaseRef. Everything is explicit now. The most obvious impact of this is
that on Page.deinit, we have to releaseRef every MO, IO and blob held by the
page.
This change removes a number of special-cases to deal with various ownership
patterns. For example, Iterators are now properly reference counted and when their
RC reaches 0, they can safely releaseRef on their list. This also elimites
use-after-free potential when 2 RC objects reference each other. This should
eliminate some WPT crashes (e.g. /editing/run/insertimage.html)
(1) - We were only ever lazy about releaseRef during shutdown, so this change
won't result in more aggressive collection.
(2) Since 1 object can be referenced from 0-N IsolatedWorlds, it would be more
accurate to say that the finalizer callback is removed when all referencing
IsolatedWorld finalize it.
- Removed unused ImageContent from protocol.
- Simplified CallToolResult back to only support TextContent.
- Cleaned up CallToolResult usages in tools.zig.
- Fixed CDP inactivity timeout by resetting it when the browser is busy (loading or executing macrotasks).
- Removed the placeholder screenshot tool.
- Refactored MCP tool schemas to constants to avoid duplication.
- Configurable navigation timeouts and wait strategies in MCP tools.
- Default navigation timeout increased from 2s to 10s.
- Added navigate, eval, and screenshot MCP tools.
- Supported running a CDP server alongside MCP using --cdp-port.
- Fixed various startup crashes when running CDP in MCP mode.
- Hardened MCP server error handling.
We need to take the self-reference to the XHR object as soon as the request is
made. Previously, we were waiting until we got the start callback, but v8 could
(and does) drop the reference before that happens. Unfortunately, that means
we can no longer use _transfer == null to tell if we own a reference or not, so
a new boolean was added.
V8 needs our help when serializing host (e.g. a Zig dom instance) objects. We
don't currently have this implemented, so this provides the callback that throws
an error. Our wrapper returns Nothing when no callback is provided, which v8
doesn't allow (via assertion).
These new optional parameter run AFTER --wait-until, allowing the (imo) useful
combination of `--wait-until load --wait-script "report.complete === true"`.
However, if `--wait-until` IS NOT specified but `--wait-selector/script` IS,
then there is no default wait and it'll just check the selector/script. If
neither `--wait-selector` or `--wait-script/--wait-script-file` are specified
then `--wait-until` continues to default to `done`.
These waiters were added to the Runner, and the existing Action.waitForSelector
now uses the runner's version. Selector querying has been split into distinct
parse and query functions, so that we can parse once, and query on every tick.
We could potentially optimize --wait-script to compile the script once and call
it on each tick, but we'd have to detect page navigation to recompile the script
in the new context. Something I'd rather optimize separately.
These changes all better align with chrome's event ordering/timing.
There are two big changes. The first is that our internal page_navigated event,
which is kind of our heavy hitter, is sent once the header is received as
opposed to (much later) on document load. The main goal of this internal event
is to trigger the "Page.frameNavigated" CDP event which is meant to happen
once the URL is committed, which _is_ on header response.
To accommodate this earlier trigger, new explicit events for DOMContentLoaded
and load have be added.
This drastically changes the flow of events as things go from:
Start Page Navigation
Response Received
Start Frame Navigation
Response Received
End Frame Navigation
End Page Navigation
context clear + reset
DOMContentLoaded
Loaded
TO:
Start Page Navigation
Response Received
End Page Navigation
context clear + reset
Start Frame Navigation
Response Received
End Frame Navigation
DOMContentLoaded
Loaded
So not only does it remove the nesting, but it ensures that the context are
cleared and reset once the main page's navigation is locked in, and before any
frame is created.
