Supporting unbuffered fetches is actually part of the fetch spec in its
HTTP-network-fetch algorithm. We had previously implemented this method
in a very ad-hoc manner as a simple wrapper around ResourceLoader. This
is still the case, but we now implement a good amount of these steps
according to spec, using ResourceLoader's unbuffered API. The response
data is forwarded through to the fetch response using streams.
This will eventually let us remove the use of ResourceLoader's buffered
API, as all responses should just be streamed this way. The streams spec
then supplies ways to wait for completion, thus allowing fully buffered
responses. However, we have more work to do to make the other parts of
our fetch implementation (namely, Body::fully_read) use streams before
we can do this.
This callback is meant to be triggered by streams, which does not always
provide a WebIDL::DOMException. Pass a plain value instead. Of all the
users of this callback, only one actually uses the value, and already
converts the DOMException to a plain value.
Performing a lookup in the blob URL registry does not work in the case
of a web worker - as the registry is not shared between processes.
However - the URL itself passed to a worker has the blob attached to it,
which we can pull out of the URL on a fetch.
There were several instances where the spec marks an AO invocation as
infallible, but we were propagating WebIDL::ExceptionOr. These mostly
cannot throw due to knowledge about the values they are provided. By
unwinding these, we can remove a decent amount of exception handling.
This was resulting in a whole lot of rebuilding whenever a new IDL
interface was added.
Instead, just directly include the prototype in every C++ file which
needs it. While we only really need a forward declaration in each cpp
file; including the full prototype header (which itself only includes
LibJS/Object.h, which is already transitively brought in by
PlatformObject) - it seems like a small price to pay compared to what
feels like a full rebuild of LibWeb whenever a new IDL file is added.
Given all of these includes are only needed for the ::initialize
method, there is probably a smart way of avoiding this problem
altogether. I've considered both using some macro trickery or generating
these functions somehow instead.
Fetched bodies can be on the order of gigabytes, so rather than crashing
when we hit OOM here, we can simply invoke the error callback with a DOM
exception. We use "UnknownError" here as the spec directly supports this
for OOM errors:
UnknownError: The operation failed for an unknown transient reason
(e.g. out of memory).
This is still an ad-hoc implementation. We should be using streams, and
we do have the AOs available to do so. But they need to be massaged to
be compatible with callers of Body::fully_read. And once we do use
streams, this function will become infallible - so making it infallible
here is at least a step in the right direction.
The only subclass was already GC-allocated, so let's hoist the JS::Cell
inheritance up one level. This ends up simplifying a bit of rather
dubious looking code where we were previously slicing ESOs.
Changes the signature of queue_fetch_task() from AK:Function to
JS::HeapFunction to be more clear to the user of the function that this
is what it uses internally.
Changes the signature of queue_global_task() from AK:Function to
JS::HeapFunction to be more clear to the user of the function that this
is what it uses internally.
Previously, calling fetch with a signal object provided by
`AbortSignal.timeout()` would cause a crash when the signal timed out.
We now push a `TemporaryExecutionContext` to the stack when we invoke
the signal's abort steps, as an execution context is required when
calling native functions.
