continuwuity/src
Benjamin Lee 3de3d8ea54
remove sync response cache
This cache can serve invalid responses, and has an extremely low hit
rate.

It serves invalid responses because because it's only keyed off
the `since` parameter, but many of the other request parameters also
affect the response or it's side effects. This will become worse once we
implement filtering, because there will be a wider space of parameters
with different responses. This problem is fixable, but not worth it
because of the low hit rate.

The low hit rate is because normal clients will always issue the next
sync request with `since` set to the `prev_batch` value of the previous
response. The only time we expect to see multiple requests with the same
`since` is when the response is empty, but we don't cache empty
responses.

This was confirmed experimentally by logging cache hits and misses over
15 minutes with a wide variety of clients. This test was run on
matrix.computer.surgery, which has only a few active users, but a
large volume of sync traffic from many rooms. Over the test period, we
had 3 hits and 5309 misses. All hits occurred in the first minute, so I
suspect that they had something to do with client recovery from an
offline state. The clients that were connected during the test are:

 - element web
 - schildichat web
 - iamb
 - gomuks
 - nheko
 - fractal
 - fluffychat web
 - fluffychat android
 - cinny web
 - element android
 - element X android

Fixes: #336
2024-05-17 09:52:16 -07:00
..
alloc resolve ptr_as_ptr lint 2024-05-03 01:52:29 -04:00
api remove sync response cache 2024-05-17 09:52:16 -07:00
config config option to auto-remediate bad users joining bad rooms or servers 2024-05-09 17:44:15 -04:00
database Revert "rocksdb: enable async_io if using io_uring feature" 2024-05-10 22:56:44 -04:00
router add security response HTTP headers if not present 2024-05-09 09:53:04 -04:00
service remove sync response cache 2024-05-17 09:52:16 -07:00
utils media: return our detected MIME type for Content-Type 2024-05-12 15:54:22 -04:00
main.rs use function comments for lsp here 2024-05-03 01:52:29 -04:00