[HADOOP-14276] Add a nanosecond API to Time/Timer/FakeTimer

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.9.0, 2.7.4, 3.0.0-alpha4, 2.8.2
• Component/s: util
• Hadoop Flags: Reviewed
• Assignee: Erik Krogen
• Reporter: Erik Krogen
• Created: 04/Apr/17 19:27
• Updated: 08/Jun/17 03:09
• Resolved: 07/Apr/17 21:05

Description

Right now Time/Timer export functionality for retrieving time at a millisecond-level precision but not at a nanosecond-level precision, which is required for some applications (there's ~70 usages). Most of these seem not to need mocking functionality for tests; only one class currently mocks this out (LightWeightCache) but we would like to add another as part of HDFS-11615 and want to avoid code duplication. This could be useful for other classes in the future as well.

Issue Links

• breaks: HADOOP-14293 Initialize FakeTimer with a less trivial value
• is required by: HDFS-11615 FSNamesystemLock metrics can be inaccurate due to millisecond precision