[HDDS-1175] Serve read requests directly from RocksDB

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Component/s: OM HA, Ozone Manager
• Labels: pull-request-available
• Target Version/s: 0.5.0
• Assignee: Hanisha Koneru
• Reporter: Hanisha Koneru
• Created: 25/Feb/19 19:45
• Updated: 07/Jan/21 11:18
• Resolved: 07/Mar/19 03:45

Description

We can directly server read requests from the OM's RocksDB instead of going through the Ratis server. OM should first check its role and only if it is the leader can it server read requests. 

There can be a scenario where an OM can lose its Leader status but not know about the new election in the ring. This OM could server stale reads for the duration of the heartbeat timeout but this should be acceptable (similar to how Standby Namenode could possibly server stale reads till it figures out the new status).

Issue Links

• links to: GitHub Pull Request #557