[HDFS-2560] Refactor BPOfferService to be a static inner class

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.23.0
• Fix Version/s: 0.23.1
• Component/s: datanode
• Target Version/s: HA branch (HDFS-1623), 0.23.1
• Hadoop Flags: Reviewed
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 17/Nov/11 06:08
• Updated: 27/May/15 16:47
• Resolved: 18/Nov/11 00:46

Description

Currently BPOfferService is a non-static inner class of DataNode. For HA we are adding another inner class inside of this, which makes the scope very hard to understand when reading the code (and has resulted in subtle bugs like HDFS-2529 where a variable is referenced from the wrong scope. Making it a static inner class with a reference to the DN has two advantages: a) scope is now explicit, and b) enables unit testing of the BPOS against a mocked-out DN.

Issue Links

• breaks: HDFS-8486 DN startup may cause severe data loss