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From "Yongjun Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-12202) Provide new set of FileSystem API to bypass external attribute provider
Date Wed, 26 Jul 2017 19:45:00 GMT
Yongjun Zhang created HDFS-12202:
------------------------------------

             Summary: Provide new set of FileSystem API to bypass external attribute provider
                 Key: HDFS-12202
                 URL: https://issues.apache.org/jira/browse/HDFS-12202
             Project: Hadoop HDFS
          Issue Type: New Feature
          Components: hdfs, hdfs-client
            Reporter: Yongjun Zhang


HDFS client uses 

{code}
  /**
   * Return a file status object that represents the path.
   * @param f The path we want information from
   * @return a FileStatus object
   * @throws FileNotFoundException when the path does not exist
   * @throws IOException see specific implementation
   */
  public abstract FileStatus getFileStatus(Path f) throws IOException;

  /**
   * List the statuses of the files/directories in the given path if the path is
   * a directory.
   * <p>
   * Does not guarantee to return the List of files/directories status in a
   * sorted order.
   * <p>
   * Will not return null. Expect IOException upon access error.
   * @param f given path
   * @return the statuses of the files/directories in the given patch
   * @throws FileNotFoundException when the path does not exist
   * @throws IOException see specific implementation
   */
  public abstract FileStatus[] listStatus(Path f) throws FileNotFoundException,
                                                         IOException;

{code}
to get FileStatus of files.

When external attribute provider (INodeAttributeProvider) is enabled for a cluster, the  external
attribute provider is consulted to get back some relevant info (including ACL, group etc)
and returned back in FileStatus, 

There is a problem here, when we use distcp to copy files from srcCluster to tgtCluster, if
srcCluster has external attribute provider enabled, the data we copied would contain data
from attribute provider, which we may not want.

Create this jira to add a new set of interface for distcp to use, so that distcp can copy
HDFS data only and bypass external attribute provider data.

The new set API would look like
{code}
 /**
   * Return a file status object that represents the path.
   * @param f The path we want information from
   * @param bypassExtAttrProvider if true, bypass external attr provider
   *        when it's in use.
   * @return a FileStatus object
   * @throws FileNotFoundException when the path does not exist
   * @throws IOException see specific implementation
   */
  public FileStatus getFileStatus(Path f,
      final boolean bypassExtAttrProvider) throws IOException;

  /**
   * List the statuses of the files/directories in the given path if the path is
   * a directory.
   * <p>
   * Does not guarantee to return the List of files/directories status in a
   * sorted order.
   * <p>
   * Will not return null. Expect IOException upon access error.
   * @param f
   * @param bypassExtAttrProvider if true, bypass external attr provider
   *        when it's in use.
   * @return
   * @throws FileNotFoundException
   * @throws IOException
   */
  public FileStatus[] listStatus(Path f,
      final boolean bypassExtAttrProvider) throws FileNotFoundException,
                                                  IOException;
{code}

So when bypassExtAttrProvider is true, external attribute provider will be bypassed.

Thanks.




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