[HADOOP-8244] Improve comments on ByteBufferReadable.read

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.2-alpha
• Hadoop Flags: Reviewed
• Assignee: Henry Robinson
• Reporter: Henry Robinson
• Created: 03/Apr/12 19:57
• Updated: 11/Oct/12 17:45
• Resolved: 04/Apr/12 23:36

Description

There are a couple of ways in which the comment on ByteBufferReadable.read can be improved. Since this is a public-facing API with potentially many implementations, it's worth taking the time to get it right.

• We should describe what can become of the byte buffer state in the case of an exception (is the limit changed? where's the position?). For the DFSInputStream implementation, position and limit are unchanged if there is an error, but I don't think that's the right think to mandate for all implementations.
• We should mention explicitly that 0-byte reads are legitimate - this is particularly important in light of HDFS-3110 which detects support for direct reads by issuing a 0-byte read from libhdfs.