Avoid expensive cross-hierarchy dynamic_cast from JS::Object to
UniversalGlobalScopeMixin on every microtask checkpoint.
Since UniversalGlobalScopeMixin is not in the JS::Object
inheritance chain, as<UniversalGlobalScopeMixin>(JS::Object&)
falls through to dynamic_cast, which is very costly. Profiling
showed this taking ~14% of total CPU time.
Add EnvironmentSettingsObject::universal_global_scope() backed
by a pointer cached eagerly during initialization.
Replace the BytecodeFactory header with cbindgen.
This will help ensure that types and enums and constants are kept in
sync between the C++ and Rust code. It's also a step in exporting more
Rust enums directly rather than relying on magic constants for
switch statements.
The FFI functions are now all placed in the JS::FFI namespace, which
is the cause for all the churn in the scripting parts of LibJS and
LibWeb.
When parse_off_thread() completes, the result callback runs inside a
deferred_invoke, which executes outside the HTML event loop's task
model. This meant that any microtasks queued by the callback (e.g.
promise reactions from react_to_promise during module linking) were
never drained, since HTML::EventLoop::process() only performs
microtask checkpoints after executing an HTML task.
Fix this by performing an explicit microtask checkpoint after the
parse result callback. This ensures that promise reactions queued
during module linking are drained immediately.
This fixes module worker scripts timing out because their loading
promise chains would stall indefinitely.
Use the parse_off_thread() helper to submit
parse_program(ProgramType::Module) to the ThreadPool for parsing
on a worker thread. Bounce back to the main thread to compile and
deliver the result via deferred_invoke.
Falls back to synchronous parsing when the Rust pipeline is
unavailable (LIBJS_CPP=1 or LIBJS_COMPARE_PIPELINES=1).
Create a SourceCode on the main thread (performing UTF-8 to UTF-16
conversion), then submit parse_program() to the ThreadPool for
Rust parsing on a worker thread. This unblocks the WebContent event
loop during external script loading.
Add Script::create_from_parsed() and
ClassicScript::create_from_pre_parsed() factory methods that take a
pre-parsed RustParsedProgram and a SourceCode, performing only the
GC-allocating compile step on the main thread.
Falls back to synchronous parsing when the Rust pipeline is
unavailable (LIBJS_CPP=1 or LIBJS_COMPARE_PIPELINES=1).
Issue #6294 describes an edge case where the browser crash if the same
module is loaded three times in a document, but all attempts fail.
Failure scenario:
1. Module load 1 set the state to "Fetching"
2. Module load 2 registers a callback to `on_complete` since the
current state is "Fetching"
3. Module load 1 finish with a failure, invoking the callback for load
number 2
4. Module load 3 cause a crash. The state is neither "Fetching" or
"ModuleScript", so we'll reset the state to "Fetching". This invokes
the callback for module load 2 again, now with an unexpected state
which will cause an assert violation.
Proposed fix is to remove the condition that invokes `on_complete`
immediately for successfully loaded modules only, the callback should
be invoked regardless of whether the fetch succeeded or failed.
This reveals a separate bug in HTMLScriptElement, where
`mark_as_ready()` can be invoked before
`m_steps_to_run_when_the_result_is_ready` is assigned.
This appears to be a spec bug, reported as
https://github.com/whatwg/html/issues/12073 and addressed by delaying
the callback by a task, similar to the issue was resolved for inline
scripts.
The end goal here is for LibHTTP to be the home of our RFC 9111 (HTTP
caching) implementation. We currently have one implementation in LibWeb
for our in-memory cache and another in RequestServer for our disk cache.
The implementations both largely revolve around interacting with HTTP
headers. But in LibWeb, we are using Fetch's header infra, and in RS we
are using are home-grown header infra from LibHTTP.
So to give these a common denominator, this patch replaces the LibHTTP
implementation with Fetch's infra. Our existing LibHTTP implementation
was not particularly compliant with any spec, so this at least gives us
a standards-based common implementation.
This migration also required moving a handful of other Fetch AOs over
to LibHTTP. (It turns out these AOs were all from the Fetch/Infra/HTTP
folder, so perhaps it makes sense for LibHTTP to be the implementation
of that entire set of facilities.)
An upcoming commit will migrate the contents of Headers.h/cpp to LibHTTP
for use outside of LibWeb. These CORS and MIME helpers depend on other
LibWeb facilities, however, so they cannot be moved.
We have a couple of ways to designate spec notes and (our) developer
notes in comments, but we never really settled on a single approach. As
a result, we have a bit of a mixed bag of note comments on our hands.
To the extent that I could find them, I changed developer notes to
`// NB: ...` and changed spec notes to `// NOTE: ...`. The rationale for
this is that in most web specs, notes are prefixed by `NOTE: ...` so
this makes it easier to copy paste verbatim. The choice for `NB: ...` is
pretty arbitrary, but it makes it stand out from the regular spec notes
and it was already in wide use in our codebase.
Atlassian login gets the base URL for its module scripts by throwing an
error and pulling out the current script's URL from error.stack with
regex.
Since we only returned a basename for module scripts, it would fail to
match and try and use `/` as a base URL (because it does
[matched_string] + "/"), which is not a valid base URL.
While debugging a spec-compliant implementation of ReadableStreamPipeTo,
I spent a lot of time inspecting promise internals. This is much less
noisy if we halve the number of temporary promises.
PrimitiveString is now internally either UTF-8, UTF-16, or both.
We no longer convert them to/from ByteString anywhere, nor does VM have
a ByteString cache.
This patch removes those unused 2 algorithms:
1. `fetch_internal_module_script_graph`
2. `fetch_descendants_of_a_module_script`
Those 2 algorithms were removed in spec and are not used in our
codebase.
These variables are all captured in queued events or other event loop
tasks, but are all guarded by event loop spins later in the function.
The IGNORE_USE_IN_ESCAPING_LAMBDA will soon be required for all locals
that are captured by ref in GC::Function as well as AK::Function.
An environment settings object will return a copy to the URL. From a
quick glance, we could probably make an environment settings object
return a reference to one, but let's just change this code to make
a copy since its not safe to rely on that.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
Now that the heap has no knowledge about a JavaScript realm and is
purely for managing the memory of the heap, it does not make sense
to name this function to say that it is a non-realm variant.
