Add locking to more safely delete state groups: Part 1 #18107
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Currently we don't really have anything that stops us from deleting state groups when an in-flight event references it. This is a fairly rare race currently, but we want to be able to more aggresively delete state groups so it is important to address this to ensure that the database remains valid. See the class docstring of the new data store for an explanation for how this works.
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synapse/storage/schema/state/delta/89/01_state_groups_deletion.sql
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Co-authored-by: Devon Hudson <[email protected]>
Co-authored-by: Devon Hudson <[email protected]>
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synapse/storage/schema/state/delta/89/01_state_groups_deletion.sql
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Co-authored-by: Devon Hudson <[email protected]>
….sql Co-authored-by: Devon Hudson <[email protected]>
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This actually makes it so that deleting state groups goes via the new mechanism. c.f. #18107
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Regressed as part of #18107 This does two things: 1. Only check if the state groups have been deleted when calculating the event context (as that's when we will insert them). This avoids lots of checks for read operations. 2. Don't lock the `state_groups` rows when doing the check. This adds overhead, and it doesn't prevent any races.
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Currently we don't really have anything that stops us from deleting state groups when an in-flight event references it. This is a fairly rare race currently, but we want to be able to more aggressively delete state groups so it is important to address this to ensure that the database remains valid.
This implements the locking, but doesn't actually use it.
See the class docstring of the new data store for an explanation for how this works.