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https://issues.apache.org/jira/browse/HADOOP-4044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12629271#action_12629271
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Doug Cutting commented on HADOOP-4044:
--------------------------------------
> That imposes restriction on what SymLink can point to.
I don't follow what you mean here.
> we could of course propose another FS.open() that returns something more than
> an FSInputStream.
Yes, I drafted this and deleted it, since it's rather hairy and not clearly an
advantage to anything but HDFS. Here it is:
{code}
public class FileOpening {
public FileOpening(boolean isLink, Path link) { ... }
public boolean isLink() { ... }
public Path getLink() { ... }
}
public FileOpening getFileOpening(Path f) throws IOException {
FileStatus stat = getFileOpening(f);
return new FileOpening(stat.isLink(), stat.getLink());
}
public FSDataInputStream open(Path f, int bufferSize) throws IOException {
FileSystem fs = this;
FileOpening opening = fs.getFileOpening(f);
for (opening.isSymLink()) {
f = opening.getSymLink();
fs = f.getFileSystem(getConf());
opening = fs.getOpening(f);
}
return fs.openData(f, opening, bufferSize);
}
public abstract FSDataInputStream openData(Path f, FileOpening opening, int
bufferSize)
throws IOException;
{code}
HDFS would override getFileOpening() to return a subclass that also contains
block locations. Phew! Would anyone leverage this but HDFS?
> Create symbolic links in HDFS
> -----------------------------
>
> Key: HADOOP-4044
> URL: https://issues.apache.org/jira/browse/HADOOP-4044
> Project: Hadoop Core
> Issue Type: New Feature
> Components: dfs
> Reporter: dhruba borthakur
> Assignee: dhruba borthakur
> Attachments: symLink1.patch
>
>
> HDFS should support symbolic links. A symbolic link is a special type of file
> that contains a reference to another file or directory in the form of an
> absolute or relative path and that affects pathname resolution. Programs
> which read or write to files named by a symbolic link will behave as if
> operating directly on the target file. However, archiving utilities can
> handle symbolic links specially and manipulate them directly.
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