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From "Colin Patrick McCabe (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-711) hdfsUtime does not handle atime = 0 or mtime = 0 correctly
Date Fri, 06 Jul 2012 22:29:34 GMT

    [ https://issues.apache.org/jira/browse/HDFS-711?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13408402#comment-13408402
] 

Colin Patrick McCabe commented on HDFS-711:
-------------------------------------------

Unfortunately the decision was made to use time_t as the parameter for hdfsUtime.  That type
is sometimes signed, and sometimes unsigned, so it doesn't really make sense to require users
to pass -1, in my opinion.  (It would work on modern versions of Linux, though.)  (The use
of time_t causes other problems-- it is only 32 bit on 32-bit Linux systems, for example.)

It would be nice to have a better API that exposed the true resolution of the HDFS utime (currently
we're limited to seconds only, whereas HDFS tracks milliseconds.)  However, that's a separate
issue, I think...
                
> hdfsUtime does not handle atime = 0 or mtime = 0 correctly
> ----------------------------------------------------------
>
>                 Key: HDFS-711
>                 URL: https://issues.apache.org/jira/browse/HDFS-711
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: documentation
>    Affects Versions: 0.20.1
>            Reporter: freestyler
>            Assignee: Colin Patrick McCabe
>         Attachments: HDFS-711.001.patch
>
>
> in HADOOP/src/c++/libhdfs/hdfs.h
> The following function document is incorrect:
> /*   @param mtime new modification time or 0 for only set access time in seconds
>       @param atime new access time or 0 for only set modification time in seconds
> */
>     int hdfsUtime(hdfsFS fs, const char* path, tTime mtime, tTime atime);
> Currently, setting mtime or atime to 0 has no special meaning. That is, file last modified
time will change to 0 if the mtime argument is 0.
> libhdfs should translate mtime = 0 or atime = 0 to the special value -1, which in HDFS
means "don't change this time."

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