Ignore replayed commands on the metastore.

[benbjohnson]

Overview

This commit changes the metastore to ignore any commands that are replayed against it. This is typically handled by the messaging.Conn but there's no sense in panicing in the metastore if a replayed message comes through.

[otoolep]

LGTM.

[otoolep]

If this happens though, is it an indication of a bug?

[benbjohnson]

It looks like the main issue is that Conn.SetIndex() isn't being called. Although even when it is called we could get in a race where a reconnection on the Conn is done after an index is applied but before the Conn.Index is updated.

The other option is to inject Conn with an Index() getter func that retrieves the index of the metastore but that seems like it couples the two together too tightly.

[jwilder]

👍