As `summary` and `summary.sig` aren’t immutable, HTTP requests to
download them can be optimised by sending the `If-None-Match` and
`If-Modified-Since` headers to avoid unnecessarily re-downloading them
if they haven’t changed since last being checked.
Hook them up to the new support for that in the fetcher.
The `ETag` and `Last-Modified` for each file in the cache are stored as
the `user.etag` xattr and the mtime, respectively. For flatpak, for
example, this affects the cached files in
`~/.local/share/flatpak/repo/tmp/cache/summaries`.
If xattrs aren’t supported, or if the server doesn’t support the caching
headers, the pull behaviour is unchanged from before.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Add support in the soup and curl fetchers to send the `If-None-Match`
and `If-Modified-Since` request headers, and pass on the `ETag` and
`Last-Modified` response headers.
This currently introduces no functional changes, but once call sites
provide the appropriate integration, this will allow HTTP caching to
happen with requests (typically with metadata requests, where the data
is not immutable due to being content-addressed). That should reduce
bandwidth requirements.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Philip Withnall