We now partition the HTTP disk cache based on the Vary response header.
If a cached response contains a Vary header, we look for each of the
header names in the outgoing HTTP request. The outgoing request must
match every header value in the original request for the cache entry
to be used; otherwise, a new request will be issued, and a separate
cache entry will be created.
Note that we must now defer creating the disk cache file itself until we
have received the response headers. The Vary key is computed from these
headers, and affects the partitioned disk cache file name.
There are further optimizations we can make here. If we have a Vary
mismatch, we could find the best candidate cached response and issue a
conditional HTTP request. The content server may then respond with an
HTTP 304 if the mismatched request headers are actually okay. But for
now, if we have a Vary mismatch, we issue an unconditional request as
a purely correctness-oriented patch.
We need to store request headers in order to handle Vary mismatches.
(Note we should also be using BLOB for header storage in sqlite, as they
are not necessarily UTF-8.)
We currently set the response time to when the cache entry writer is
created. This is more or less the same as the request start time, so
this is not correct.
This was a regression from 5384f84550.
That commit changed when the writer was created, but did not move the
setting of the response time to match.
We now set the response time to when the HTTP response headers have been
received (again), which matches how Chromium behaves:
https://source.chromium.org/chromium/chromium/src/+/refs/tags/144.0.7500.0:net/url_request/url_request_job.cc;l=425-433
A future commit will format memory cache debug messages similarly to the
disk cache messages. To make it easy to read them both at a glance when
both debug flags are turned on, let's add a prefix to these messages.
If the cURL request completes with anything other than CURLE_OK, we must
not keep the cache entry. For example, if the server's connection closes
while transferring data, we receive CURLE_PARTIAL_FILE. We don't want
this cache entry to be treated as valid in a subsequent request.
This directive allows our disk cache to serve stale responses for a time
indicated by the directive itself, while we revalidate the response in
the background.
Issuing requests that weren't initiated by a client is a new thing for
RequestServer. In this implementation, we associate the request with
the client that initiated the request to the stale cache entry. This
adds a "background request" mode to the Request object, to prevent us
from trying to send any of the revalidation response over IPC.
We currently have two ongoing implementations of RFC 9111, HTTP caching.
In order to consolidate these, this patch moves the implementation from
RequestServer to LibHTTP for re-use within LibWeb.
2025-11-29 08:35:02 -05:00
Renamed from Services/RequestServer/Cache/CacheEntry.cpp (Browse further)
