Commit graph

1 commit

Author SHA1 Message Date
Joey Orlando
1df1b1eaa0
patch redis cluster multi-key operations (#3496)
# Which issue(s) this PR fixes

Related to https://github.com/grafana/oncall-private/issues/2363

Addresses this issue that arises when using
`cache.get_many`/`cache.set_many` operations with a Redis Cluster:
```python3
File "/usr/local/lib/python3.11/site-packages/redis/cluster.py", line 1006, in determine_slot
    raise RedisClusterException(
redis.exceptions.RedisClusterException: MGET - all keys must map to the same key slot
```

From the Redis Cluster
[docs](https://redis.io/docs/reference/cluster-spec/#hash-tags), this
can be addressed with this 👇 . Basically this will ensure that keys in
multi-key operations will resolve to the same hash slot (read: node):

> Hash tags
> There is an exception for the computation of the hash slot that is
used in order to implement hash tags. Hash tags are a way to ensure that
multiple keys are allocated in the same hash slot. This is used in order
to implement multi-key operations in Redis Cluster.
> 
> To implement hash tags, the hash slot for a key is computed in a
slightly different way in certain conditions. If the key contains a
"{...}" pattern only the substring between { and } is hashed in order to
obtain the hash slot. However since it is possible that there are
multiple occurrences of { or } the algorithm is well specified by the
following rules:
> 
> IF the key contains a { character.
> AND IF there is a } character to the right of {.
> AND IF there are one or more characters between the first occurrence
of { and the first occurrence of }.
> Then instead of hashing the key, only what is between the first
occurrence of { and the following first occurrence of } is hashed.

## Checklist

- [x] Unit, integration, and e2e (if applicable) tests updated
- [ ] Documentation added (or `pr:no public docs` PR label added if not
required)
- [ ] `CHANGELOG.md` updated (or `pr:no changelog` PR label added if not
required)
2023-12-04 13:08:57 -05:00