[HDFS-6086] Fix a case where zero-copy or no-checksum reads were not allowed even when the block was cached

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.0
• Fix Version/s: 2.4.0
• Component/s: datanode
• Target Version/s: 2.4.0
• Assignee: Colin P. McCabe
• Reporter: Colin P. McCabe
• Created: 11/Mar/14 02:26
• Updated: 10/Apr/14 13:11
• Resolved: 11/Mar/14 22:43

Description

We need to fix a case where zero-copy or no-checksum reads are not allowed even when the block is cached. The case is when the block is cached before the REQUEST_SHORT_CIRCUIT_FDS operation begins. In this case, DataXceiver needs to consult the ShortCircuitRegistry to see if the block is cached, rather than relying on a callback.