[HIVE-13523] Fix connection leak in ORC RecordReader and refactor for unit testing

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 2.0.1, 2.1.0
• Component/s: ORC
• Target Version/s: 2.0.1, 2.1.0
• Assignee: Thomas Poepping
• Reporter: Thomas Poepping
• Created: 14/Apr/16 23:07
• Updated: 21/Jun/16 15:12
• Resolved: 18/Apr/16 21:09

Description

In RecordReaderImpl, a MetadataReaderImpl object was being created (opening a file), but never closed, causing a leak. This change closes the Metadata object in RecordReaderImpl, and does substantial refactoring to make RecordReaderImpl testable:

• Created DataReaderFactory and MetadataReaderFactory (plus default implementations) so that the create() methods can be mocked to verify that the objects are actually closed in RecordReaderImpl.close()
• Created MetadataReaderProperties and DataReaderProperties to clean up argument lists, making code more readable
• Created a builder() for RecordReaderImpl to make the code more readable
• DataReader and MetadataReader now extend closeable (there was no reason for them not to in the first place) so I can use the guava Closer interface: http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/io/Closer.html
• Use the Closer interface to guarantee that regardless of if either close() call fails, both will be attempted (preventing further potential leaks)
• Create builders for MetadataReaderProperties, DataReaderProperties, and RecordReaderImpl to help with code readability