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
* Fix bug where a new writer advances their token too quickly
When starting a new writer (for e.g. persisting events), the
`MultiWriterIdGenerator` doesn't have a minimum token for it as there
are no rows matching that new writer in the DB.
This results in the the first stream ID it acquired being announced as
persisted *before* it actually finishes persisting, if another writer
gets and persists a subsequent stream ID. This is due to the logic of
setting the minimum persisted position to the minimum known position of
across all writers, and the new writer starts off not being considered.
* Fix sending out POSITIONs when our token advances without update
Broke in #14820
* For replication HTTP requests, only wait for minimal position
This is because if a worker reaches ~100% CPU then everything starts
lagging and we hit the log line a lot. When at error we invoke sentry
and that has a lot of overhead, which then puts even more pressure on
the worker.
Refactoring to use both the user ID & the device ID when tracking
the currently syncing users in the presence handler.
This is done both locally and over replication. Note that the device
ID is discarded but will be used in a future change.
Refactoring to pass the device ID (in addition to the user ID) through
the presence handler (specifically the `user_syncing`, `set_state`,
and `bump_presence_active_time` methods and their replication
versions).
Simplify some of the presence code by reducing duplicated code between
worker & non-worker modes.
The main change is to push some of the logic from `user_syncing` into
`set_state`. This is done by passing whether the user is setting the presence
via a `/sync` with a new `is_sync` flag to `set_state`. If this is `true` some
additional logic is performed:
* Don't override `busy` presence.
* Update the `last_user_sync_ts`.
* Never update the status message.
All the information needed is already in the `instance_map`, so
use that instead of passing the hostname / IP & port manually
for each replication request.
This consolidates logic for future improvements of using e.g.
UNIX sockets for workers.
* Add SSL options to redis config
* fix lint issues
* Add documentation and changelog file
* add missing . at the end of the changelog
* Move client context factory to new file
* Rename ssl to tls and fix typo
* fix lint issues
* Added when redis attributes were added
* Add master to the instance_map as part of Complement, have ReplicationEndpoint look at instance_map for master.
* Fix typo in drive by.
* Remove unnecessary worker_replication_* bits from unit tests and add master to instance_map(hopefully in the right place)
* Several updates:
1. Switch from master to main for naming the main process in the instance_map. Add useful constants for easier adjustment of names in the future.
2. Add backwards compatibility for worker_replication_* to allow time to transition to new style. Make sure to prioritize declaring main directly on the instance_map.
3. Clean up old comments/commented out code.
4. Adjust unit tests to match with new code.
5. Adjust Complement setup infrastructure to only add main to the instance_map if workers are used and remove now unused options from the worker.yaml template.
* Initial Docs upload
* Changelog
* Missed some commented out code that can go now
* Remove TODO comment that no longer holds true.
* Fix links in docs
* More docs
* Remove debug logging
* Apply suggestions from code review
Co-authored-by: reivilibre <olivier@librepush.net>
* Apply suggestions from code review
Co-authored-by: reivilibre <olivier@librepush.net>
* Update version to latest, include completeish before/after examples in upgrade notes.
* Fix up and docs too
---------
Co-authored-by: reivilibre <olivier@librepush.net>
Separate out a HTTP client for replication in preparation for
also supporting using UNIX sockets. The major difference from
the base class is that this does not use treq to handle HTTP
requests.
* Have replication clients remove _INT_STREAM_POS
Suppose worker A makes an internal http request from worker B. B may
make changes that A later learns about over replication. We want A's
request to block until it has seen those changes—mainly to ensure A's
caches are invalidated promptly. This helps provide read-after-write
consistency, eliminating entire categories of races and test flakes.
To implement this, B includes a top-level field `_INT_STREAM_POS` in its
response JSON. Roughly speaking, the field's value tells A what to wait
for. But we weren't removing that internal field before A's request
completed!
Introduced in https://github.com/matrix-org/synapse/pull/14820.
Fixes#15308.
* Changelog
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.
David Robertson