UpdateMetadata RPC should update table path cache

[wuchong]

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Description

Currently, UpdateMetadata RPC only updates coordinator and tablet server informations in the cluster, but we should also update table path information in the cluster. This has already added in the RPC protocol, but didn't implement in Coordinator side and TabletServer side.

Willingness to contribute

• I'm willing to submit a PR!

[caozhen1937]

@wuchong, I would like to implement it. Can you assign it to me?

In CoordinatorEventProcessor#updateServerMetadataCache, get all tablePath by MetadataManager.

[wuchong]

@caozhen1937 Getting all tablePath by MetadataManager is a very heavy operation for zookeeper and should be avoided. The implementation is a little complex. We need to send updateMetadata for every table creation and deletion and also when the initialization of a coordiinator server.

This task is in a high priority, thus I have been working it. Thanks for volunteering.

[wuchong]

cc @swuferhong