Remove cache for get_shared_rooms_for_users#9416
Conversation
clokep
left a comment
There was a problem hiding this comment.
This PR looks fine, but it does seem like we're doing a lot of work to invalidate caches for something that may or may not be called frequently.
|
Yeah, after thinking about this a bit I think it's probably just best to lose the cache. We'd indeed spend so much work invalidating it that I don't think it's particularly enough to offset the benefit of keeping it. That said, ideally we would rate-limit this endpoint, though the spec doesn't suggest to: matrix-org/matrix-spec-proposals#2666. |
It's not clear that the benefit of caching this function outweighs the performance cost of invalidating the cache when the underlying tables change.
a588ee5 to
3787d8e
Compare
|
I've updated this PR to just remove the cache instead, as it seemed more costly to invalidate it. |
Beforehand, with the cache added, multiple calls would give back the same results, even if the users started sharing a new room in-between those calls. Removing the cache should fix the problem, but it's a good idea to add tests to cache the mistake in the future; in case we do decide to add a cache again.
3787d8e to
94022c4
Compare
clokep
left a comment
There was a problem hiding this comment.
Seems reasonable to me! 👍 The test changes just look like some code de-duplication.
| ) -> None: | ||
| """Insert entries into the users_who_share_private_rooms table. The first | ||
| user should be a local user. | ||
| """Insert entries into the users_in_public_rooms table. |
There was a problem hiding this comment.
I think it was a copy/paste error from the method above (add_users_who_share_private_room).
Code de-duping and making sure a second call happens to the |
Synapse 1.29.0 (2021-03-08) =========================== Note that synapse now expects an `X-Forwarded-Proto` header when used with a reverse proxy. Please see [UPGRADE.rst](UPGRADE.rst#upgrading-to-v1290) for more details on this change. No significant changes. Synapse 1.29.0rc1 (2021-03-04) ============================== Features -------- - Add rate limiters to cross-user key sharing requests. ([\#8957](matrix-org/synapse#8957)) - Add `order_by` to the admin API `GET /_synapse/admin/v1/users/<user_id>/media`. Contributed by @dklimpel. ([\#8978](matrix-org/synapse#8978)) - Add some configuration settings to make users' profile data more private. ([\#9203](matrix-org/synapse#9203)) - The `no_proxy` and `NO_PROXY` environment variables are now respected in proxied HTTP clients with the lowercase form taking precedence if both are present. Additionally, the lowercase `https_proxy` environment variable is now respected in proxied HTTP clients on top of existing support for the uppercase `HTTPS_PROXY` form and takes precedence if both are present. Contributed by Timothy Leung. ([\#9372](matrix-org/synapse#9372)) - Add a configuration option, `user_directory.prefer_local_users`, which when enabled will make it more likely for users on the same server as you to appear above other users. ([\#9383](matrix-org/synapse#9383), [\#9385](matrix-org/synapse#9385)) - Add support for regenerating thumbnails if they have been deleted but the original image is still stored. ([\#9438](matrix-org/synapse#9438)) - Add support for `X-Forwarded-Proto` header when using a reverse proxy. ([\#9472](matrix-org/synapse#9472), [\#9501](matrix-org/synapse#9501), [\#9512](matrix-org/synapse#9512), [\#9539](matrix-org/synapse#9539)) Bugfixes -------- - Fix a bug where users' pushers were not all deleted when they deactivated their account. ([\#9285](matrix-org/synapse#9285), [\#9516](matrix-org/synapse#9516)) - Fix a bug where a lot of unnecessary presence updates were sent when joining a room. ([\#9402](matrix-org/synapse#9402)) - Fix a bug that caused multiple calls to the experimental `shared_rooms` endpoint to return stale results. ([\#9416](matrix-org/synapse#9416)) - Fix a bug in single sign-on which could cause a "No session cookie found" error. ([\#9436](matrix-org/synapse#9436)) - Fix bug introduced in v1.27.0 where allowing a user to choose their own username when logging in via single sign-on did not work unless an `idp_icon` was defined. ([\#9440](matrix-org/synapse#9440)) - Fix a bug introduced in v1.26.0 where some sequences were not properly configured when running `synapse_port_db`. ([\#9449](matrix-org/synapse#9449)) - Fix deleting pushers when using sharded pushers. ([\#9465](matrix-org/synapse#9465), [\#9466](matrix-org/synapse#9466), [\#9479](matrix-org/synapse#9479), [\#9536](matrix-org/synapse#9536)) - Fix missing startup checks for the consistency of certain PostgreSQL sequences. ([\#9470](matrix-org/synapse#9470)) - Fix a long-standing bug where the media repository could leak file descriptors while previewing media. ([\#9497](matrix-org/synapse#9497)) - Properly purge the event chain cover index when purging history. ([\#9498](matrix-org/synapse#9498)) - Fix missing chain cover index due to a schema delta not being applied correctly. Only affected servers that ran development versions. ([\#9503](matrix-org/synapse#9503)) - Fix a bug introduced in v1.25.0 where `/_synapse/admin/join/` would fail when given a room alias. ([\#9506](matrix-org/synapse#9506)) - Prevent presence background jobs from running when presence is disabled. ([\#9530](matrix-org/synapse#9530)) - Fix rare edge case that caused a background update to fail if the server had rejected an event that had duplicate auth events. ([\#9537](matrix-org/synapse#9537)) Improved Documentation ---------------------- - Update the example systemd config to propagate reloads to individual units. ([\#9463](matrix-org/synapse#9463)) Internal Changes ---------------- - Add documentation and type hints to `parse_duration`. ([\#9432](matrix-org/synapse#9432)) - Remove vestiges of `uploads_path` configuration setting. ([\#9462](matrix-org/synapse#9462)) - Add a comment about systemd-python. ([\#9464](matrix-org/synapse#9464)) - Test that we require validated email for email pushers. ([\#9496](matrix-org/synapse#9496)) - Allow python to generate bytecode for synapse. ([\#9502](matrix-org/synapse#9502)) - Fix incorrect type hints. ([\#9515](matrix-org/synapse#9515), [\#9518](matrix-org/synapse#9518)) - Add type hints to device and event report admin API. ([\#9519](matrix-org/synapse#9519)) - Add type hints to user admin API. ([\#9521](matrix-org/synapse#9521)) - Bump the versions of mypy and mypy-zope used for static type checking. ([\#9529](matrix-org/synapse#9529))
This PR remove the cache for the
get_shared_rooms_for_usersstorage method (the db method driving the experimental "what rooms do I share with this user?" feature: MSC2666). Currently subsequent requests to the endpoint will return the same result, even if your shared rooms with that user have changed.The cache was added in #7785, but we forgot to ensure it was invalidated appropriately.
Upon attempting to invalidate it, I found that the cache had to be entirely invalidated whenever a user (remote or local) joined or left a room. This didn't make for a very useful cache, especially for a function that may or may not be called very often. Thus, I've opted to remove it instead of invalidating it.
If there's a way to partially invalidate this cache when a user leaves/joins a room, then that may be a case for bringing it back. But at the moment I don't think that's possible (especially if it requires a costly DB query just to do so).