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https://issues.apache.org/jira/browse/HADOOP-9972?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13769653#comment-13769653
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Colin Patrick McCabe commented on HADOOP-9972:
----------------------------------------------
Proposed new APIs (in FileSystem and FileContext):
{code}
FileStatus[] listStatus(Path path, PathOptions options) throws IOException;
FileStatus[] globStatus(Path path, PathOptions options) throws IOException;
{code}
The {{PathOptions}} class will contain three fields:
{code}
private PathFilter pathFilter;
private PathErrorHandler errorHandler;
private Boolean resolveSymlinks;
{code}
{{PathFilter}} serves the same purpose that it currently does-- filtering out
paths from the results.
{{PathErrorHandler}} has a {{handleError}} function taking a {{Path}} and
{{IOException}}. This function gets invoked whenever there is an IOException.
It can choose to rethrow the exception, log the exception and continue, or
simply ignore it completely.
{{resolveSymlinks}} determines whether we should fully resolve all symlinks
that we come across. If it is set, we will never get back a FileStatus for a
symlink from either {{listStatus}} or {{globStatus}}.
We can add more fields to {{PathOptions}} later if it becomes necessary.
> new APIs for listStatus and globStatus to deal with symlinks
> ------------------------------------------------------------
>
> Key: HADOOP-9972
> URL: https://issues.apache.org/jira/browse/HADOOP-9972
> Project: Hadoop Common
> Issue Type: Improvement
> Components: fs
> Affects Versions: 2.1.1-beta
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
>
> Based on the discussion in HADOOP-9912, we need new APIs for FileSystem to
> deal with symlinks. The issue is that code has been written which is
> incompatible with the existence of things which are not files or directories.
> For example,
> there is a lot of code out there that looks at FileStatus#isFile, and
> if it returns false, assumes that what it is looking at is a
> directory. In the case of a symlink, this assumption is incorrect.
> It seems reasonable to make the default behavior of {{FileSystem#listStatus}}
> and {{FileSystem#globStatus}} be fully resolving symlinks, and ignoring
> dangling ones. This will prevent incompatibility with existing MR jobs and
> other HDFS users. We should also add new versions of listStatus and
> globStatus that allow new, symlink-aware code to deal with symlinks as
> symlinks.
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