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https://issues.apache.org/jira/browse/HADOOP-14872?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16210786#comment-16210786
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Steve Loughran commented on HADOOP-14872:
-----------------------------------------
Oh, it's not so big. Sorry I've not had time to look at it. One thing to
consider is could we use the github PRs as part of the review process. I know
if we do that Yetus will switch to github mode, but I'm getting more used to
it's view of the world, and how its history works. Still doesn't handle large
scale patches though
> CryptoInputStream should implement unbuffer
> -------------------------------------------
>
> Key: HADOOP-14872
> URL: https://issues.apache.org/jira/browse/HADOOP-14872
> Project: Hadoop Common
> Issue Type: Improvement
> Components: fs
> Affects Versions: 2.6.4
> Reporter: John Zhuge
> Assignee: John Zhuge
> Attachments: HADOOP-14872.001.patch, HADOOP-14872.002.patch,
> HADOOP-14872.003.patch, HADOOP-14872.004.patch, HADOOP-14872.005.patch,
> HADOOP-14872.006.patch, HADOOP-14872.007.patch, HADOOP-14872.008.patch,
> HADOOP-14872.009.patch, HADOOP-14872.010.patch, HADOOP-14872.011.patch,
> HADOOP-14872.012.patch
>
>
> Discovered in IMPALA-5909.
> Opening an encrypted HDFS file returns a chain of wrapped input streams:
> {noformat}
> HdfsDataInputStream
> CryptoInputStream
> DFSInputStream
> {noformat}
> If an application such as Impala or HBase calls HdfsDataInputStream#unbuffer,
> FSDataInputStream#unbuffer will be called:
> {code:java}
> try {
> ((CanUnbuffer)in).unbuffer();
> } catch (ClassCastException e) {
> throw new UnsupportedOperationException("this stream does not " +
> "support unbuffering.");
> }
> {code}
> If the {{in}} class does not implement CanUnbuffer, UOE will be thrown. If
> the application is not careful, tons of UOEs will show up in logs.
> In comparison, opening an non-encrypted HDFS file returns this chain:
> {noformat}
> HdfsDataInputStream
> DFSInputStream
> {noformat}
> DFSInputStream implements CanUnbuffer.
> It is good for CryptoInputStream to implement CanUnbuffer for 2 reasons:
> * Release buffer, cache, or any other resource when instructed
> * Able to call its wrapped DFSInputStream unbuffer
> * Avoid the UOE described above. Applications may not handle the UOE very
> well.
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