[HDFS-3190] Simple refactors in existing NN code to assist QuorumJournalManager extension

• Type: Sub-task
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0.0-alpha
• Fix Version/s: 3.0.0, 2.0.2-alpha
• Component/s: namenode
• Target Version/s: 2.0.0-alpha
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 03/Apr/12 22:01
• Updated: 11/Oct/12 18:46
• Resolved: 03/Jul/12 01:00

Description

This JIRA is for some simple refactors in the NN:

• refactor the code which writes the seen_txid file in NNStorage into a new "LongContainingFile" utility class. This is useful for the JournalNode to atomically/durably record its last promised epoch
• refactor the interface from FileJournalManager back to StorageDirectory to use a StorageErrorReport interface. This allows FileJournalManager to be used in isolation of a full StorageDirectory.