rabbit_db: Copy feature states early when joining a cluster #9682
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This is probably the result of a copy-paste.
[Why] When a Khepri-based node joins a Mnesia-based cluster, it is reset and switches back from Khepri to Mnesia. If there are Mnesia files left in its data directory, Mnesia will restart with stale/incorrect data and the operation will fail. After a migration to Khepri, we need to make sure there is no stale Mnesia files. [How] We use `rabbit_mnesia` to query the Mnesia files and delete them.
[Why] This relies on Mnesia and is only useful when using Mnesia. Indeed, there is no partition handling when Khepri is used.
[Why] `reset_registry/0` reset the in-memory states so far, but left the on-disk record. This is inconsistent. [How] After resetting the in-memory states, we remove the file on disk.
…disk [Why] Sometimes, we need to reset the in-memory registry only, like when we restart the `rabbit` application, not the whole Erlang node. However, sometimes, we also need to delete the feature states on disk. This is the case when a node joins a cluster. [How] We expose a new `reset/0` function which covers both the in-memory and on-disk states. This will be used in a follow-up commit to correctly reset the feature flags states in `rabbit_db_cluster:join/2`.
[Why] So far, the feature states were copied from the cluster after the actual join. However, the join may have reloaded the feature flags registry, using the previous on-disk record, defeating the purpose of copying the cluster's states. This was done in this order to have a simpler error handling. [How] This time, we copy the remote cluster's feature states just after the reset. If the join fails, we reset the feature flags again, including the on-disk states.
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Why
So far, the feature states were copied from the cluster after the actual join. However, the join may have reloaded the feature flags registry, using the previous on-disk record, defeating the purpose of copying the cluster's states.
This was done in this order to have a simpler error handling.
How
This time, we copy the remote cluster's feature states just after the reset.
If the join fails, we reset the feature flags again, including the on-disk states.