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https://issues.apache.org/jira/browse/HADOOP-11039?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Colin Patrick McCabe updated HADOOP-11039:
------------------------------------------
Resolution: Fixed
Fix Version/s: 2.7.0
Status: Resolved (was: Patch Available)
> ByteBufferReadable API doc is inconsistent with the implementations.
> --------------------------------------------------------------------
>
> Key: HADOOP-11039
> URL: https://issues.apache.org/jira/browse/HADOOP-11039
> Project: Hadoop Common
> Issue Type: Bug
> Components: documentation
> Reporter: Yi Liu
> Assignee: Yi Liu
> Priority: Minor
> Fix For: 2.7.0
>
> Attachments: HADOOP-11039.001.patch
>
>
> In {{ByteBufferReadable}}, API doc of {{int read(ByteBuffer buf)}} says:
> {quote}
> After a successful call, buf.position() and buf.limit() should be unchanged,
> and therefore any data can be immediately read from buf. buf.mark() may be
> cleared or updated.
> {quote}
> {quote}
> @param buf
> the ByteBuffer to receive the results of the read operation.
> Up to
> buf.limit() - buf.position() bytes may be read.
> {quote}
> But actually the implementations (e.g. {{DFSInputStream}},
> {{RemoteBlockReader2}}) would be:
> *Upon return, buf.position() will be advanced by the number of bytes read.*
> code implementation of {{RemoteBlockReader2}} is as following:
> {code}
> @Override
> public int read(ByteBuffer buf) throws IOException {
> if (curDataSlice == null || curDataSlice.remaining() == 0 &&
> bytesNeededToFinish > 0) {
> readNextPacket();
> }
> if (curDataSlice.remaining() == 0) {
> // we're at EOF now
> return -1;
> }
> int nRead = Math.min(curDataSlice.remaining(), buf.remaining());
> ByteBuffer writeSlice = curDataSlice.duplicate();
> writeSlice.limit(writeSlice.position() + nRead);
> buf.put(writeSlice);
> curDataSlice.position(writeSlice.position());
> return nRead;
> }
> {code}
> This description is very important and will guide user how to use this API,
> and all the implementations should keep the same behavior. We should fix the
> javadoc.
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