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https://issues.apache.org/jira/browse/HADOOP-15625?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16767032#comment-16767032
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Steve Loughran commented on HADOOP-15625:
-----------------------------------------
ben: you've to the permissions to attach a patch now. Have a look at the
testing.md doc for hadoop-aws to see the homework you get to do
At a quick look @ the patch
* you'll need to change that describe() statement
* I'd like to retain a test of larger -> shorter as well as shorter -> larger,
because for openstack swift it was the first sequence which failed the most
* what exception gets raised?
I'd like to have this fail with some special subclass of EOFException, i.e
RemotFileChangedException or similar, because EOFExceptions are
expected/processed specially in layers above. And we'll need to add some
details in the troubleshooting.md file
> S3A input stream to use etags to detect changed source files
> ------------------------------------------------------------
>
> Key: HADOOP-15625
> URL: https://issues.apache.org/jira/browse/HADOOP-15625
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 3.2.0
> Reporter: Brahma Reddy Battula
> Assignee: Brahma Reddy Battula
> Priority: Major
> Attachments: HADOOP-15625-001.patch, HADOOP-15625-002.patch,
> HADOOP-15625-003.patch
>
>
> S3A input stream doesn't handle changing source files any better than the
> other cloud store connectors. Specifically: it doesn't noticed it has
> changed, caches the length from startup, and whenever a seek triggers a new
> GET, you may get one of: old data, new data, and even perhaps go from new
> data to old data due to eventual consistency.
> We can't do anything to stop this, but we could detect changes by
> # caching the etag of the first HEAD/GET (we don't get that HEAD on open with
> S3Guard, BTW)
> # on future GET requests, verify the etag of the response
> # raise an IOE if the remote file changed during the read.
> It's a more dramatic failure, but it stops changes silently corrupting things.
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