This PR fixes the issue described as comment here:
https://github.com/element-hq/synapse/issues/18793#issuecomment-3502202379
In Element Call, this shows up as ghost participants: someone who left
the call keeps being displayed until a later state change refreshes the
room.
The bug is not specific to Element Call: any state event can be
affected, RTC membership just changes often enough to make it visible.
## What happens
Alice has a client syncing against a homeserver where events are
persisted by one worker (the event persister) and `/sync` is served by
another (the sync worker). Her client is parked in a long-poll: `GET
/sync?since=s99&timeout=30000`.
Bob joins a call at the same moment Carol sends a message. Carol's
message reaches the persister first; Bob's `m.call.member` arrives while
that write is still in flight, so the per-room persist queue groups them
into one transaction:
```
events (each gets its own stream ordering):
stream_ordering 100: m.room.message Carol
stream_ordering 101: m.call.member Bob (state)
current_state_delta_stream (how state_after finds state changes):
stream_id 100 ────► (m.call.member, @bob) -> $bob_join_call
▲
└─ stamped with the batch MINIMUM (100), not the event's own 101
(see `_update_current_state_txn`)
```
The transaction commits: both events and the delta row are now in the
database, atomically.
The persister then announces the new events over replication, one RDATA
token per stream ordering — rows are only merged into one token when
they share a position, and 100 and 101 don't. So the sync worker's
events-stream position steps 99 → 100 → 101, and on reaching 100 it
pokes the notifier.
Alice's long-poll wakes at exactly that moment. Her response is built at
the worker's *current* position — `end = 100` — with RDATA 101 still in
the queue:
```
Sync A (since=99, end=100):
timeline: events 99 < ordering ≤ 100 → [Carol's message]
state_after: deltas 99 < stream_id ≤ 100 → [$bob_join_call] ← delivered EARLY
next_batch: s100 ← mid-batch token
```
No race on the client's side is needed: the server *hands out* the
mid-batch token as `next_batch`. Alice's client re-polls with it, as
every sync client does. The worker has meanwhile processed RDATA 101:
```
Sync B (since=100, end=101):
timeline: events 100 < ordering ≤ 101 → [Bob's m.call.member @101] ✓
state_after: deltas 100 < stream_id ≤ 101 → [] row is stamped 100 ✗
```
A state event in the timeline with an empty `state_after`. An MSC4222
client trusts `state_after` over timeline state events, so Alice's copy
of Bob's call membership never updates from this response.
On a single process this cannot happen: the batch's stream IDs are
released as a whole, so the position visible to `/sync` jumps 99 → 101
and `s100` is never handed out. Only a process that learns its position
from replication — any sync worker — ticks through the middle of a
batch.
### Pull Request Checklist
<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->
* [x] Pull request is based on the develop branch
* [x] Pull request includes a [changelog
file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog).
The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
- Use markdown where necessary, mostly for `code blocks`.
- End with either a period (.) or an exclamation mark (!).
- Start with a capital letter.
- Feel free to credit yourself, by adding a sentence "Contributed by
@github_username." or "Contributed by [Your Name]." to the end of the
entry.
* [x] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct (run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))
Adds a `redis.username` config option.
Details:
A `username` without a `password` (or `password_path`) is refused at
startup. Redis has no wire form for a username without a password, and
txredisapi only sends `AUTH` when a password is set, so the username
would otherwise be silently ignored. An explicitly empty password is
accepted, since that is how a `nopass` ACL user is configured.
This relies on txredisapi 1.4.12, the first release to accept a
`username` kwarg. That upstream support was contributed by @karolyi
specifically to unblock this.
Fixes#19238.
### Pull Request Checklist
<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->
* [X] Pull request is based on the develop branch
* [X] Pull request includes a [changelog
file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog).
The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
- Use markdown where necessary, mostly for `code blocks`.
- End with either a period (.) or an exclamation mark (!).
- Start with a capital letter.
- Feel free to credit yourself, by adding a sentence "Contributed by
@github_username." or "Contributed by [Your Name]." to the end of the
entry.
* [X] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct (run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))
---------
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
The registration of `QuarantinedMediaStream` in
`ReplicationCommandHandler._streams_to_replicate` was missed when the
stream was added, so an instance configured as the
quarantined_media_changes stream writer never sent RDATA/POSITION for it
unless it was the main process.
Also add the stream to the `instance_map` config validation.
Stream was introduced in
https://github.com/element-hq/synapse/pull/19558
Fixes https://github.com/element-hq/synapse/issues/20080
---------
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
This means you can use `get_success(...)` anywhere regardless
of what kind of work needs to be done.
Spawning from adding some more async Rust things in
https://github.com/element-hq/synapse/pull/19846 and wanting something
more standard instead of the custom `till_deferred_has_result(...)` that
has crept in to a few files.
Alternative to https://github.com/element-hq/synapse/pull/19867 spurred
on by [this
comment](https://github.com/element-hq/synapse/pull/19867#discussion_r3441774685)
from @erikjohnston
### How does this work?
Previously, `get_success(...)` just ran in a hot-loop advancing the
Twisted reactor clock which didn't give any time for other threads to do
some work or acquire the GIL if necessary (whenever there is a hand-off
from Rust to Python, we need the GIL).
Now, `get_success(...)` loops until we see a result (until we hit the
~0.1s real-time timeout). In the loop, we call
[`time.sleep(0)`](https://docs.python.org/3/library/time.html#time.sleep)
which will "Suspend execution of the calling thread [...]" (CPU and GIL)
to allow other threads to do some work. Then like before, we advance the
Twisted reactor clock to run any scheduled callbacks which includes
anything the other threads may have scheduled.
### Does this slow down the entire test suite?
Seems just as fast as before. There is minutes variance in what we had
before and after but both are within the same range of each other.
(see PR for actual before/after timings)
Introduce `Clock.call_when_running(...)` to wrap startup code in a
logcontext, ensuring we can identify which server generated the logs.
Background:
> Ideally, nothing from the Synapse homeserver would be logged against the `sentinel`
> logcontext as we want to know which server the logs came from. In practice, this is not
> always the case yet especially outside of request handling.
>
> Global things outside of Synapse (e.g. Twisted reactor code) should run in the
> `sentinel` logcontext. It's only when it calls into application code that a logcontext
> gets activated. This means the reactor should be started in the `sentinel` logcontext,
> and any time an awaitable yields control back to the reactor, it should reset the
> logcontext to be the `sentinel` logcontext. This is important to avoid leaking the
> current logcontext to the reactor (which would then get picked up and associated with
> the next thing the reactor does).
>
> *-- `docs/log_contexts.md`
Also adds a lint to prefer `Clock.call_when_running(...)` over
`reactor.callWhenRunning(...)`
Part of https://github.com/element-hq/synapse/issues/18905
During the migration the automated script to update the copyright
headers accidentally got rid of some of the existing copyright lines.
Reinstate them.
If a worker reconnects to Redis we send out the current positions of all our streams. However, if we're also trying to send out a backlog of RDATA at the same time then we can end up sending a `POSITION` with the current token *before* we've sent all the RDATA before the current token.
This doesn't cause actual bugs as the receiving servers see the POSITION, fetch the relevant rows from the DB, and then ignore the old RDATA as they come in. However, this is inefficient so it'd be better if we didn't send out-of-order positions
With Redis commands do not need to be re-issued by the main
process (they fan-out to all processes at once) and thus it is no
longer necessary to worry about them reflecting recursively forever.
We were incorrectly checking if the *local* token had been advanced, rather than the token for the remote instance.
In practice, I don't think this has caused any bugs due to where we use `wait_for_stream_position`, as critically we don't use it on instances that also write to the given streams (and so the local token will lag behind all remote tokens).
Since the object it returns is a ReplicationCommandHandler.
This is clean-up from adding support to Redis where the command handler
was added as an additional layer of abstraction from the TCP protocol.
Part of #9744
Removes all redundant `# -*- coding: utf-8 -*-` lines from files, as python 3 automatically reads source code as utf-8 now.
`Signed-off-by: Jonathan de Jong <jonathan@automatia.nl>`
Running `dmypy run` will do a `mypy` check while spinning up a daemon
that makes rerunning `dmypy run` a lot faster.
`dmypy` doesn't support `follow_imports = silent` and has
`local_partial_types` enabled, so this PR enables those options and
fixes the issues that were newly raised. Note that `local_partial_types`
will be enabled by default in upcoming mypy releases.
* Split ShardedWorkerHandlingConfig
This is so that we have a type level understanding of when it is safe to
call `get_instance(..)` (as opposed to `should_handle(..)`).
* Remove special cases in ShardedWorkerHandlingConfig.
`ShardedWorkerHandlingConfig` tried to handle the various different ways
it was possible to configure federation senders and pushers. This led to
special cases that weren't hit during testing.
To fix this the handling of the different cases is moved from there and
`generic_worker` into the worker config class. This allows us to have
the logic in one place and allows the rest of the code to ignore the
different cases.
This allows trailing commas in multi-line arg lists.
Minor, but we might as well keep our formatting current with regard to
our minimum supported Python version.
Signed-off-by: Dan Callahan <danc@element.io>
Make sure that the AccountDataStream presents complete updates, in the right
order.
This is much the same fix as #7337 and #7358, but applied to a different stream.
Paul Chobert