[
https://issues.apache.org/jira/browse/HADOOP-11452?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15802980#comment-15802980
]
Sanjay Radia commented on HADOOP-11452:
---------------------------------------
*Some background:*
# FileSystem#rename(src, dest, options) originally served as a temporary
implementation of FileContext#rename(src, dest, options). Hence it was kept
protected. It was deprecated when the implementation in AbstractFileSystem
called dfsClient.rename(...) which btw is atomic as noted in this Jira.
# Why didn't we make it public with the correct impl. The expectation was that
all Hadoop apps would move to FIleContext. The flaw in that plan was that apps
like Hive neeed to run on both Hadoop 1 and Hadoop 2 and they picked the lowest
common denominator: Hadoop 1 which only has FileSystem. We should have back
ported FileContext to Hadoop 1. Big mistake.
Going forward there is little chance of removing FileSystem since many
customers probably use it directly. Hence I am okay with FileSystem#rename(src,
dest, options) becoming public and having a correct implementation (ie call
dfsClient#rename(...). However we should only do this ONLY if we feel
customers/apps need the OVERWRITE flag.
I have already commented on the Rename.ATOMIC_REQUIRED. My vote is -1 for this
option as I explained in my comment above. We could move the
Rename.ATOMIC_REQUIRED part to a separate jira if folks want to discuss this
further and move forward on making rename-with-options public.
> Revisit FileSystem.rename(path, path, options)
> ----------------------------------------------
>
> Key: HADOOP-11452
> URL: https://issues.apache.org/jira/browse/HADOOP-11452
> Project: Hadoop Common
> Issue Type: Task
> Components: fs
> Affects Versions: 2.7.3
> Reporter: Yi Liu
> Assignee: Steve Loughran
> Attachments: HADOOP-11452-001.patch, HADOOP-11452-002.patch
>
>
> Currently in {{FileSystem}}, {{rename}} with _Rename options_ is protected
> and with _deprecated_ annotation. And the default implementation is not
> atomic.
> So this method is not able to be used outside. On the other hand, HDFS has a
> good and atomic implementation. (Also an interesting thing in {{DFSClient}},
> the _deprecated_ annotations for these two methods are opposite).
> It makes sense to make public for {{rename}} with _Rename options_, since
> it's atomic for rename+overwrite, also it saves RPC calls if user desires
> rename+overwrite.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: common-issues-unsubscr...@hadoop.apache.org
For additional commands, e-mail: common-issues-h...@hadoop.apache.org
