[HDFS-5285] Flatten INodeFile hierarchy: Add UnderContruction Feature

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.4.0
• Component/s: namenode
• Hadoop Flags: Reviewed
• Assignee: Jing Zhao
• Reporter: Tsz-wo Sze
• Created: 01/Oct/13 14:58
• Updated: 04/Sep/14 01:15
• Resolved: 22/Nov/13 01:39

Description

For files, there are INodeFile, INodeFileUnderConstruction, INodeFileWithSnapshot and INodeFileUnderConstructionWithSnapshot for representing whether a file is under construction or whether it is in some snapshot. The following are two major problems of the current approach:

• Java class does not support multiple inheritances so that INodeFileUnderConstructionWithSnapshot cannot extend both INodeFileUnderConstruction and INodeFileWithSnapshot.
• The number of classes is exponential to the number of features. Currently, there are only two features, UnderConstruction and WithSnapshot. The number of classes is 2^2 = 4. It is hard to add one more feature since the number of classes will become 2^3 = 8.

As a first step, we implement an Under-Construction feature to replace INodeFileUnderConstruction and INodeFileUnderConstructionWithSnapshot in this jira.

Issue Links

• incorporates: HDFS-4746 ClassCastException in BlockManager.addStoredBlock() due to that blockReceived came after file was closed.