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https://issues.apache.org/jira/browse/HDFS-5781?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jing Zhao updated HDFS-5781:
----------------------------

    Description: 
HDFS-5674 uses Enum.values and enum.ordinal to identify an editlog op for a 
given byte value. While improving the efficiency, it may cause issue. E.g., 
when several new editlog ops are added to trunk around the same time (for 
several different new features), it is hard to backport the editlog ops with 
larger byte values to branch-2 before those with smaller values, since there 
will be gaps in the byte values of the enum. 

This jira plans to still use an array to record the mapping between editlog ops 
and their byte values, and allow gap between valid ops. 

  was:
HDFS-5674 uses Enum.values and enum.ordinal to identify an editlog op for a 
given byte value. While improving the efficiency, it may cause issue. E.g., 
when several new editlog ops are added to trunk around the same time (for 
several different new features), it is hard to backport the editlog ops with 
larger byte values to branch-2 before those with smaller values, since there 
will be gaps in the byte values of the enum. 

This jira plans to still use a map to record the mapping between editlog ops 
and their byte values. 


> Use an array to record the mapping between FSEditLogOpCode and the 
> corresponding byte value
> -------------------------------------------------------------------------------------------
>
>                 Key: HDFS-5781
>                 URL: https://issues.apache.org/jira/browse/HDFS-5781
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: namenode
>    Affects Versions: 2.4.0
>            Reporter: Jing Zhao
>            Assignee: Jing Zhao
>            Priority: Minor
>         Attachments: HDFS-5781.000.patch, HDFS-5781.001.patch, 
> HDFS-5781.002.patch, HDFS-5781.002.patch
>
>
> HDFS-5674 uses Enum.values and enum.ordinal to identify an editlog op for a 
> given byte value. While improving the efficiency, it may cause issue. E.g., 
> when several new editlog ops are added to trunk around the same time (for 
> several different new features), it is hard to backport the editlog ops with 
> larger byte values to branch-2 before those with smaller values, since there 
> will be gaps in the byte values of the enum. 
> This jira plans to still use an array to record the mapping between editlog 
> ops and their byte values, and allow gap between valid ops. 



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