We currently spin the event loop to wait for the specified element to
become available. As we've seen with other endpoints, this can result
in dead locks if another web component also spins the event loop.
This patch makes the locator implementations asynchronous.
This input event handling change is intended to address the following
design issues:
- Having `DOM::Position` is unnecessary complexity when `Selection`
exists because caret position could be described by the selection
object with a collapsed state. Before this change, we had to
synchronize those whenever one of them was modified, and there were
already bugs caused by that, i.e., caret position was not changed when
selection offset was modified from the JS side.
- Selection API exposes selection offset within `<textarea>` and
`<input>`, which is not supposed to happen. These objects should
manage their selection state by themselves and have selection offset
even when they are not displayed.
- `EventHandler` looks only at `DOM::Text` owned by `DOM::Position`
while doing text manipulations. It works fine for `<input>` and
`<textarea>`, but `contenteditable` needs to consider all text
descendant text nodes; i.e., if the cursor is moved outside of
`DOM::Text`, we need to look for an adjacent text node to move the
cursor there.
With this change, `EventHandler` no longer does direct manipulations on
caret position or text content, but instead delegates them to the active
`InputEventsTarget`, which could be either
`FormAssociatedTextControlElement` (for `<input>` and `<textarea>`) or
`EditingHostManager` (for `contenteditable`). The `Selection` object is
used to manage both selection and caret position for `contenteditable`,
and text control elements manage their own selection state that is not
exposed by Selection API.
This change improves text editing on Discord, as now we don't have to
refocus the `contenteditable` element after character input. The problem
was that selection manipulations from the JS side were not propagated
to `DOM::Position`.
I expect this change to make future correctness improvements for
`contenteditable` (and `designMode`) easier, as now it's decoupled from
`<input>` and `<textarea>` and separated from `EventHandler`, which is
quite a busy file.
It's currently possible for window size/position updates to hang, as the
underlying IPCs are synchronous. This updates the WebDriver endpoint to
be async, to unblock the WebContent process while the update is ongoing.
The UI process is now responsible for informing WebContent when the
update is complete.
There was a timing issue here where WebDriver would dismiss a dialog,
and then invoke another endpoint before the dialog was actually closed.
This is because the dismissal first has to hop over to the UI process to
close the graphical dialog, which then asynchronously informs WebContent
of the result. It's not until WebContent receives that result that the
dialog is considered closed, thus those subsequent endpoints would abort
due a dialog being "open".
We now wait for dialogs to be fully closed before returning from the
dismissal endpoints.
Similar to commit c2cf65adac, we should
avoid spinning the event loop from the WebContent-side of the WebDriver
connection. This can result in deadlocks if another component in LibWeb
also spins the event loop.
The AO to await navigations has two event loop spinners - waiting for
the navigation to complete and for the document to reach the target
readiness state. We now use NavigationObserver and DocumentObserver to
be notified when these conditions are met. And we use the same async IPC
mechanism as script execution to notify the WebDriver process when all
conditions are met (or timed out).
A NodeIterator rooted at some element cannot produce an element before
that root. That is, in a DOM tree such as:
<div id=one><div id=two><div id=three></div></div></div>
If we create a NodeIterator rooted at element `three`, then invoking the
previousNode() method on that iterator is guaranteed to return null.
There was also a bug here where if we ever did enter the while() loop,
we would have looped indefinitely, as we were not updating the current
node.
Our currently ad-hoc method of tracking element references is basically
a process-wide map, rather than grouping elements according to their
browsing context groups. This prevents us from recognizing when an
element reference is invalid due to its browsing context having been
closed.
This implements the WebDriver spec concept of element references grouped
according to their browsing context groups.
This patch is a bit noisy because we now need to plumb the current BC
through to the element reference AOs.
This abstraction will help us to support multiple IPC transport
mechanisms going forward. For now, we only have a TransportSocket that
implements the same behavior we previously had, using Unix Sockets for
IPC.
This is strictly nicer than passing them around as i32 everywhere,
and by switching to i64 as the underlying type, ID allocation becomes as
simple as incrementing an integer.
We've added a few JS::Handle members to this class over time. Let's
avoid creating a new GC root for each of these, and explicitly add a
visitation method.
Some of this code is older than widespread use of GCPtr. These functions
returning raw pointers has been a point of confusion at times, so lets
just indicate that they are non-null.
Contradictory to the spec, the Set Timeouts endpoint should update the
existing timeouts configuration in-place, rather than replacing it. WPT
expects this, and other browsers already implement this endpoint this
way.
The spec says we don't need to await navigations if we navigate to the
same URL that we are already on, but at least in our implementation, we
should still await the page load. Otherwise, we will invoke WebDriver
endpoints on the wrong page.
We are currently trying to access the current parent and top-level
browsing contexts from the current BC itself. However, if the current BC
is closed, its association to the parent and top-level BCs is lost, and
we are no longer able to handle WebDriver endpoints involving those BCs.
Instead, let's store the parent and top-level BCs separately, and update
them in accordance with the spec.
Similar to script execution, this spins the WebDriver process until the
action is complete (rather than spinning the WebContent process, which
we've seen result in deadlocks).
In particular, we need to convert web element references to the actual
element. The AO isn't fully implemented because we will need to work out
mixing JsonValue types with JS value types, which currently isn't very
straight forward with our JSON clone algorithm.
We are currently returning a JSON object of the form:
{
"name": "element-6066-11e4-a52e-4f735466cecf",
"value": "foo"
}
Instead, we are expected to return an object of the form:
{
"element-6066-11e4-a52e-4f735466cecf": "foo"
}
It's difficult to know what we need to implement if we silently ignore
these endpoints. Let's log the endpoints and their parameters, and clean
up the wall of FIXME comments to be easier to grok.
Previously, some otherwise unimplemented WebDriver endpoints were
indicating that they had executed successful, this was causing a large
number of Web Platform Tests to time out when they should have failed.
We were only looking at the current top-level navigable and its children
when searching for the specified window handle. We need to search *all*
known navigables if the handle belongs to a window not in the current
tree.
This is one of the few endpoints that does not ensure a top-level BC is
open. It's a bit of an implementation-defined endpoint, so let's protect
against a non-existent BC explicitly.
