[HDFS-8656] Preserve compatibility of ClientProtocol#rollingUpgrade after finalization

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 2.8.0
• Fix Version/s: 2.8.0, 2.7.2, 3.0.0-alpha1
• Component/s: rolling upgrades
• Target Version/s: 2.8.0
• Assignee: Andrew Wang
• Reporter: Andrew Wang
• Created: 23/Jun/15 23:37
• Updated: 06/Jan/17 00:51
• Resolved: 26/Jun/15 18:34

Description

HDFS-7645 changed rollingUpgradeInfo to still return an RUInfo after finalization, so the DNs can differentiate between rollback and a finalization. However, this breaks compatibility for the user facing APIs, which always expect a null after finalization. Let's fix this and edify it in unit tests.

As an additional improvement, isFinalized and isStarted are part of the Java API, but not in the JMX output of RollingUpgradeInfo. It'd be nice to expose these booleans so JMX users don't need to do the != 0 check that possibly exposes our implementation details.

Issue Links

• relates to: HDFS-9426 Rollingupgrade finalization is not backward compatible
• relates to: HDFS-7894 Rolling upgrade readiness is not updated in jmx until query command is issued.
• relates to: HDFS-7645 Rolling upgrade is restoring blocks from trash multiple times