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https://issues.apache.org/jira/browse/HADOOP-16202?focusedWorklogId=538993&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-538993
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ASF GitHub Bot logged work on HADOOP-16202:
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Author: ASF GitHub Bot
Created on: 21/Jan/21 11:43
Start Date: 21/Jan/21 11:43
Worklog Time Spent: 10m
Work Description: steveloughran commented on pull request #2584:
URL: https://github.com/apache/hadoop/pull/2584#issuecomment-764587055
Thomas, to clarify a bit more
yes, an FS can choose to ignore an option, -but it must recognise the option
and so make a conscious decision "this doesn't matter"
* so with the standard length/read policy options, an FS can concude "I see
that and don't support it", and just ignore it -a decision made on an
option-by-option basis.
* if something unrecognised comes in as .must() the FS must raise an
exception "I don't recognise that".
* if something it does recognise as a .must() which it knows it doesn't
support and which it MUST be able to, then it MUST raise an exception.
Example: vectored IO will only work if the FS supports seek, which ftp
doesn't. Assuming we add an option to say "I Want vectored IO" then all
filesystems will get this out the box as a well known-and-supported feature,
but ftp will need some explicit code to say "fail if vectored IO is requested"
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Issue Time Tracking
-------------------
Worklog Id: (was: 538993)
Time Spent: 8h 50m (was: 8h 40m)
> Stabilize openFile() and adopt internally
> -----------------------------------------
>
> Key: HADOOP-16202
> URL: https://issues.apache.org/jira/browse/HADOOP-16202
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs, fs/s3, tools/distcp
> Affects Versions: 3.3.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Major
> Labels: pull-request-available
> Time Spent: 8h 50m
> Remaining Estimate: 0h
>
> The {{openFile()}} builder API lets us add new options when reading a file
> Add an option {{"fs.s3a.open.option.length"}} which takes a long and allows
> the length of the file to be declared. If set, *no check for the existence of
> the file is issued when opening the file*
> Also: withFileStatus() to take any FileStatus implementation, rather than
> only S3AFileStatus -and not check that the path matches the path being
> opened. Needed to support viewFS-style wrapping and mounting.
> and Adopt where appropriate to stop clusters with S3A reads switched to
> random IO from killing download/localization
> * fs shell copyToLocal
> * distcp
> * IOUtils.copy
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