[jira] [Commented] (HDFS-5314) Do not expose CachePool type in AddCachePoolOp

["Colin Patrick McCabe (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-5314?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13787840#comment-13787840 ] 

Colin Patrick McCabe commented on HDFS-5314:
--------------------------------------------

Currently, all of the {{CachePoolInfo}} objects we store in the edit log should have all their fields set.  However, over time, as we add more cache pool fields, we'll want to maintain backwards compatibility with the way they were previously serialized in the edit log.  This will mean deserializing a {{CachePoolInfo}} and filling in defaults for fields that didn't exist in the old version.  (These defaults must be fixed, of course.)

> Do not expose CachePool type in AddCachePoolOp
> ----------------------------------------------
>
>                 Key: HDFS-5314
>                 URL: https://issues.apache.org/jira/browse/HDFS-5314
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: namenode
>    Affects Versions: HDFS-4949
>            Reporter: Colin Patrick McCabe
>            Assignee: Colin Patrick McCabe
>         Attachments: HDFS-5314-caching.001.patch
>
>
> {{CachePool}} is an internal type which should not be exposed or used in the {{FSEditLog}}.  Because {{CachePool}} is mutable, storing a reference to it in an edit log operation could lead to the edit log operation changing as a result of the {{CachePool}} object being changed.  Instead, we should store {{CachePoolInfo}}.



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