[HDFS-10759] Change fsimage bool isStriped from boolean to an enum

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0.0-alpha1, 3.0.0-beta1, 3.0.0-alpha2
• Fix Version/s: 3.0.0-alpha2
• Component/s: hdfs
• Labels: hdfs-ec-3.0-must-do
• Assignee: Ewan Higgs
• Reporter: Ewan Higgs
• Created: 12/Aug/16 15:27
• Updated: 15/Mar/18 00:09
• Resolved: 18/Jan/17 21:32

Description

The new erasure coding project has updated the protocol for fsimage such that the INodeFile has a boolean 'isStriped'. I think this is better as an enum or integer since a boolean precludes any future block types.

For example:

enum BlockType {
  CONTIGUOUS = 0,
  STRIPED = 1,
}

We can also make this more robust to future changes where there are different block types supported in a staged rollout. Here, we would use UNKNOWN_BLOCK_TYPE as the first value since this is the default value. See here for more discussion.

enum BlockType {
  UNKNOWN_BLOCK_TYPE = 0,
  CONTIGUOUS = 1,
  STRIPED = 2,
}

But I'm not convinced this is necessary since there are other enums that don't use this approach.

Issue Links

• causes: HDFS-13287 TestINodeFile#testGetBlockType results in NPE when run alone
• is related to: HDFS-11465 Rename BlockType#CONTIGUOUS to BlockType#REPLICATED