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https://issues.apache.org/jira/browse/HDFS-246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13028164#comment-13028164
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Cyril Briquet commented on HDFS-246:
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Here's another use case:
reading a file that contains an unknown number of UTF-encoded Strings
FSDataInputStream file = openFile();
long len = file.length();
while (file.getPos() < len) {
String s = file.readUTF();
processString(s);
}
I'd be glad to learn how to implement this pattern with the current HDFS API,
besides reading the file length through FileSystem.getFileStatus().getLen()
> Add a method to get file length for Seekable, FSDataInputStream and libhdfs
> ---------------------------------------------------------------------------
>
> Key: HDFS-246
> URL: https://issues.apache.org/jira/browse/HDFS-246
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: Qi Liu
> Assignee: Qi Liu
> Attachments: HADOOP-5143-2.patch, HADOOP-5143.patch, hadoop.patch
>
>
> When open any seekable file, it should be able to get the length of the file
> via Seekable interface, since the seek method should be able to detect
> seeking beyond the end of file. Such interface can benefit distributed file
> systems by saving a network round-trip of
> FileSystem.getFileStatus(Path).getLen() for any open file.
> In libhdfs, such interface should also be exposed to make native program
> taking advantage of this change.
> I have the changes locally for all FSInputStream concrete classes. The change
> can be considered trivial, since some of the FSInputStream classes already
> have a method named getFileLength(), or a member field named size/length/end.
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