While https://github.com/matrix-org/synapse/pull/13635 stops us from doing the slow thing after we've already done it once, this PR stops us from doing one of the slow things in the first place.
Related to
- https://github.com/matrix-org/synapse/issues/13622
- https://github.com/matrix-org/synapse/pull/13635
- https://github.com/matrix-org/synapse/issues/13676
Part of https://github.com/matrix-org/synapse/issues/13356
Follow-up to https://github.com/matrix-org/synapse/pull/13815 which tracks event signature failures.
With this PR, we avoid the call to the costly `_get_state_ids_after_missing_prev_event` because the signature failure will count as an attempt before and we filter events based on the backoff before calling `_get_state_ids_after_missing_prev_event` now.
For example, this will save us 156s out of the 185s total that this `matrix.org` `/messages` request. If you want to see the full Jaeger trace of this, you can drag and drop this `trace.json` into your own Jaeger, https://gist.github.com/MadLittleMods/4b12d0d0afe88c2f65ffcc907306b761
To explain this exact scenario around `/messages` -> backfill, we call `/backfill` and first check the signatures of the 100 events. We see bad signature for `$luA4l7QHhf_jadH3mI-AyFqho0U2Q-IXXUbGSMq6h6M` and `$zuOn2Rd2vsC7SUia3Hp3r6JSkSFKcc5j3QTTqW_0jDw` (both member events). Then we process the 98 events remaining that have valid signatures but one of the events references `$luA4l7QHhf_jadH3mI-AyFqho0U2Q-IXXUbGSMq6h6M` as a `prev_event`. So we have to do the whole `_get_state_ids_after_missing_prev_event` rigmarole which pulls in those same events which fail again because the signatures are still invalid.
- `backfill`
- `outgoing-federation-request` `/backfill`
- `_check_sigs_and_hash_and_fetch`
- `_check_sigs_and_hash_and_fetch_one` for each event received over backfill
- ❗ `$luA4l7QHhf_jadH3mI-AyFqho0U2Q-IXXUbGSMq6h6M` fails with `Signature on retrieved event was invalid.`: `unable to verify signature for sender domain xxx: 401: Failed to find any key to satisfy: _FetchKeyRequest(...)`
- ❗ `$zuOn2Rd2vsC7SUia3Hp3r6JSkSFKcc5j3QTTqW_0jDw` fails with `Signature on retrieved event was invalid.`: `unable to verify signature for sender domain xxx: 401: Failed to find any key to satisfy: _FetchKeyRequest(...)`
- `_process_pulled_events`
- `_process_pulled_event` for each validated event
- ❗ Event `$Q0iMdqtz3IJYfZQU2Xk2WjB5NDF8Gg8cFSYYyKQgKJ0` references `$luA4l7QHhf_jadH3mI-AyFqho0U2Q-IXXUbGSMq6h6M` as a `prev_event` which is missing so we try to get it
- `_get_state_ids_after_missing_prev_event`
- `outgoing-federation-request` `/state_ids`
- ❗ `get_pdu` for `$luA4l7QHhf_jadH3mI-AyFqho0U2Q-IXXUbGSMq6h6M` which fails the signature check again
- ❗ `get_pdu` for `$zuOn2Rd2vsC7SUia3Hp3r6JSkSFKcc5j3QTTqW_0jDw` which fails the signature check
The root node of a thread (and events related to it) are considered
"part of a thread" when validating receipts. This allows clients which
show the root node in both the main timeline and the threaded timeline
to easily send receipts in either.
Note that threaded notifications are not created for these events, these
events created notifications on the main timeline.
The callers either set a default limit or manually handle a None-limit
later on (by setting a default value).
Update the callers to always instantiate PaginationConfig with a default
limit and then assume the limit is non-None.
Stabilize the threads API (MSC3856) by supporting (only) the v1
path for the endpoint.
This also marks the API as safe for workers since it is a read-only
API.
Implement the /threads endpoint from MSC3856.
This is currently unstable and behind an experimental configuration
flag.
It includes a background update to backfill data, results from
the /threads endpoint will be partial until that finishes.
**Before:**
```
WARNING - POST-11 - Unable to parse JSON: Expecting value: line 1 column 1 (char 0) (b'')
```
**After:**
```
WARNING - POST-11 - Unable to parse JSON from POST /_matrix/client/v3/join/%21ZlmJtelqFroDRJYZaq:hs1?server_name=hs1 response: Expecting value: line 1 column 1 (char 0) (b'')
```
---
It's possible to figure out which endpoint these warnings were coming from before but you had to follow the request ID `POST-11` to the log line that says `Completed request [...]`. Including this key information next to the JSON parsing error makes it much easier to reason whether it matters or not.
```
2022-09-29T08:23:25.7875506Z synapse_main | 2022-09-29 08:21:10,336 - synapse.http.matrixfederationclient - 299 - INFO - POST-11 - {GET-O-13} [hs1] Completed request: 200 OK in 0.53 secs, got 450 bytes - GET matrix://hs1/_matrix/federation/v1/make_join/%21ohtKoQiXlPePSycXwp%3Ahs1/%40charlie%3Ahs2?ver=1&ver=2&ver=3&ver=4&ver=5&ver=6&ver=org.matrix.msc2176&ver=7&ver=8&ver=9&ver=org.matrix.msc3787&ver=10&ver=org.matrix.msc2716v4
```
---
As a note, having no `body` is normal for the `/join` endpoint and it can handle it.
0c853e0970/synapse/rest/client/room.py (L398-L403)
Alternatively we could remove these extra logs but they are probably more usually helpful to figure out what went wrong.
