[HDFS-7955] Improve naming of classes, methods, and variables related to block replication and recovery

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Component/s: erasure-coding
• Target Version/s: 3.0.0-alpha2
• Assignee: Rakesh Radhakrishnan
• Reporter: Zhe Zhang
• Created: 18/Mar/15 18:19
• Updated: 10/Dec/16 02:00
• Resolved: 30/Nov/16 16:30

Description

Many existing names should be revised to avoid confusion when blocks can be both replicated and erasure coded. This JIRA aims to solicit opinions on making those names more consistent and intuitive.

1. In current HDFS block recovery refers to the process of finalizing the last block of a file, triggered by lease recovery. It is different from the intuitive meaning of recovering a lost block. To avoid confusion, I can think of 2 options:
   • Rename this process as block finalization or block completion. I prefer this option because this is literally not a recovery.
   • If we want to keep existing terms unchanged we can name all EC recovery and re-replication logics as reconstruction.
2. As Kai suggested under HDFS-7369, several replication-based names should be made more generic:
   • UnderReplicatedBlocks and neededReplications. E.g. we can use LowRedundancyBlocks/AtRiskBlocks, and neededRecovery/neededReconstruction.
   • PendingReplicationBlocks
   • ReplicationMonitor

I'm sure the above list is incomplete; discussions and comments are very welcome.

Issue Links

• is duplicated by: HDFS-8329 Erasure coding: Rename Striped block recovery to reconstruction to eliminate confusion.
• is related to: HDFS-8031 Follow-on work for erasure coding phase I (striping layout)

Sub-Tasks

• Erasure Coding: Rename BlockECRecoveryCommand to BlockECReconstructionCommand: Resolved
• Erasure Coding : Rename BlockRecoveryWork to BlockReconstructionWork: Resolved
• Erasure Coding: Rename replication-based names in BlockManager to more generic [part-1]: Resolved
• Erasure Coding: Rename replication-based names in BlockManager to more generic [part-2]: Resolved
• Erasure Coding: Rename replication-based names in BlockManager to more generic [part-3]: Resolved
• Erasure Coding: Deprecate replication-related config keys: Resolved
• Erasure Coding: Rename CorruptReplicasMap to CorruptRedundancyMap in BlockManager to more generic: Resolved