[HADOOP-18378] Implement readFully(long position, byte[] buffer, int offset, int length)

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.4.0
• Fix Version/s: 3.4.0, 3.3.6
• Component/s: fs/s3
• Labels: pull-request-available
• Target Version/s: 3.4.0, 3.3.6
• Hadoop Flags: Reviewed
• Assignee: Alessandro Passaro
• Reporter: Ahmar Suhail
• Created: 28/Jul/22 13:41
• Updated: 28/Jan/24 00:19
• Resolved: 06/Oct/22 11:01

Description

Implement readFully(long position, byte[] buffer, int offset, int length) in PrefetchingInputStream, as it currently uses FSInputStream's readFully which calls read(long position, byte[] buffer, int offset, int length).

This read then seeks to the position (which is ok), but then seeks back to the original starting position at the end (so always seeking back to 0). this is pretty bad for the prefetching implementation as it means lots of caching to disk and getting blocks from disk. 

when backporting. follow with HADOOP-18531

Issue Links

• causes: HADOOP-18531 assertion failure in ITestS3APrefetchingInputStream
• links to: GitHub Pull Request #4955