Commit Graph

14 Commits

Author SHA1 Message Date
Eric Eastwood 0a00b7ff14
Update black, and run auto formatting over the codebase (#9381)
- Update black version to the latest
 - Run black auto formatting over the codebase
    - Run autoformatting according to [`docs/code_style.md
`](80d6dc9783/docs/code_style.md)
 - Update `code_style.md` docs around installing black to use the correct version
2021-02-16 22:32:34 +00:00
Erik Johnston 6633a4015a
Allow moving account data and receipts streams off master (#9104) 2021-01-18 15:47:59 +00:00
Erik Johnston 8de3703d21
Make event persisters periodically announce position over replication. (#8499)
Currently background proccesses stream the events stream use the "minimum persisted position" (i.e. `get_current_token()`) rather than the vector clock style tokens. This is broadly fine as it doesn't matter if the background processes lag a small amount. However, in extreme cases (i.e. SyTests) where we only write to one event persister the background processes will never make progress.

This PR changes it so that the `MultiWriterIDGenerator` keeps the current position of a given instance as up to date as possible (i.e using the latest token it sees if its not in the process of persisting anything), and then periodically announces that over replication. This then allows the "minimum persisted position" to advance, albeit with a small lag.
2020-10-12 15:51:41 +01:00
Erik Johnston b1433bf231
Don't table scan events on worker startup (#8419)
* Fix table scan of events on worker startup.

This happened because we assumed "new" writers had an initial stream
position of 0, so the replication code tried to fetch all events written
by the instance between 0 and the current position.

Instead, set the initial position of new writers to the current
persisted up to position, on the assumption that new writers won't have
written anything before that point.

* Consider old writers coming back as "new".

Otherwise we'd try and fetch entries between the old stale token and the
current position, even though it won't have written any rows.

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>
2020-09-29 16:42:19 +01:00
Erik Johnston bd380d942f
Add checks for postgres sequence consistency (#8402) 2020-09-28 18:00:30 +01:00
Erik Johnston f112cfe5bb
Fix MultiWriteIdGenerator's handling of restarts. (#8374)
On startup `MultiWriteIdGenerator` fetches the maximum stream ID for
each instance from the table and uses that as its initial "current
position" for each writer. This is problematic as a) it involves either
a scan of events table or an index (neither of which is ideal), and b)
if rows are being persisted out of order elsewhere while the process
restarts then using the maximum stream ID is not correct. This could
theoretically lead to race conditions where e.g. events that are
persisted out of order are not sent down sync streams.

We fix this by creating a new table that tracks the current positions of
each writer to the stream, and update it each time we finish persisting
a new entry. This is a relatively small overhead when persisting events.
However for the cache invalidation stream this is a much bigger relative
overhead, so instead we note that for invalidation we don't actually
care about reliability over restarts (as there's no caches to
invalidate) and simply don't bother reading and writing to the new table
in that particular case.
2020-09-24 16:53:51 +01:00
Erik Johnston cbabb312e0
Use `async with` for ID gens (#8383)
This will allow us to hit the DB after we've finished using the generated stream ID.
2020-09-23 16:11:18 +01:00
Erik Johnston deedb91732
Fix `MultiWriterIdGenerator.current_position`. (#8257)
It did not correctly handle IDs finishing being persisted out of
order, resulting in the `current_position` lagging until new IDs are
persisted.
2020-09-08 14:26:54 +01:00
Erik Johnston bbb3c8641c
Make MultiWriterIDGenerator work for streams that use negative stream IDs (#8203)
This is so that we can use it for the backfill events stream.
2020-09-01 13:36:25 +01:00
Erik Johnston 5649b7f3d0
Fix missing _add_persisted_position (#8179)
This was forgotten in #8164.
2020-08-27 13:20:34 +01:00
Erik Johnston eba98fb024
Add functions to `MultiWriterIdGen` used by events stream (#8164) 2020-08-25 17:32:30 +01:00
Erik Johnston 76d21d14a0
Separate `get_current_token` into two. (#8113)
The function is used for two purposes: 1) for subscribers of streams to
get a token they can use to get further updates with, and 2) for
replication to track position of the writers of the stream.

For streams with a single writer the two scenarios produce the same
result, however the situation becomes complicated for streams with
multiple writers. The current `MultiWriterIdGenerator` does not
correctly handle the first case (which is not an issue as its only used
for the `caches` stream which nothing subscribes to outside of
replication).
2020-08-19 10:39:31 +01:00
Erik Johnston a7bdf98d01
Rename database classes to make some sense (#8033) 2020-08-05 21:38:57 +01:00
Erik Johnston 8123b2f909
Add MultiWriterIdGenerator. (#7281)
This will be used to coordinate stream IDs across multiple writers.

Functions as the equivalent of both `StreamIdGenerator` and
`SlavedIdTracker`.
2020-05-04 17:17:45 +01:00