[HDFS-13698] [PROVIDED Phase 2] Provided ReplicaMap should be LRU with separate lookup from normal Replicas - ASF JIRA

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Details

Type: Sub-task
Status: Open
Priority: Major
Resolution: Unresolved
Affects Version/s: None
Fix Version/s: None
Component/s: None
Labels:
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Description

The existing ReplicaMap uses ExtendedBlock to lookup the replica information. However, Provided replicas should not be in the ReplicaMap; instead they should be lookups in the AliasMap. In order to handle this case, the ReplicaMap lookups should be split into two phases:

Lookup by normal ReplicaMap (as is done now) and lookup in AliasMap to see if there is also a Provided replica. The performance of this second provided lookup should be sped up using an LRU cache.