Attach cached JavaScript bytecode sidecars to HTTP response headers so
WebContent can materialize classic and module scripts directly from a
decoded cache blob on cache hits.
Carry the disk cache vary key with the sidecar and reuse it when storing
fresh bytecode, avoiding mismatches against the augmented network
request headers used to create the cache entry.
Keep CORS-filtered module responses intact for status, MIME, and script
creation checks. Read bytecode sidecar data only from the internal
response, and treat decode or materialization failure as a cache miss
that falls back to normal source compilation.
Not super important, but this will match an upcoming ID for stale-while-
revalidate requests. It also would techinically be UB if this ID had
ever overflowed. Let's make it 64-bit while we are here to also avoid
the possibility that it ever will overflow.
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.)
Given the RequestServer created the request fd with socketpair() on
Windows and pipe2() on Unix, this abstraction avoids inlined ifdef soup
by hiding the details of how the AK::Stream and Core::Notifier are
created.
When the request is stopped, we clear its internal stream data. There is
a window where RequestServer may have sent an IPC message whose callback
will try to access that data in the time between the data being cleared
and RS receiving the stop signal. When this happens, just bail from IPC.
