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From "Tsz Wo Nicholas Sze (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-8249) Separate HdfsConstants into the client and the server side class
Date Fri, 01 May 2015 22:53:07 GMT

     [ https://issues.apache.org/jira/browse/HDFS-8249?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Tsz Wo Nicholas Sze updated HDFS-8249:
--------------------------------------
    Hadoop Flags: Reviewed

+1 patch looks good.

> Separate HdfsConstants into the client and the server side class
> ----------------------------------------------------------------
>
>                 Key: HDFS-8249
>                 URL: https://issues.apache.org/jira/browse/HDFS-8249
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: hdfs-client
>            Reporter: Haohui Mai
>            Assignee: Haohui Mai
>         Attachments: HDFS-8249.000.patch, HDFS-8249.001.patch, HDFS-8249.002.patch, HDFS-8249.003.patch,
HDFS-8249.004.patch
>
>
> The constants in {{HdfsConstants}} are used by both the client side and the server side.
There are two types of constants in the class:
> 1. Constants that are used internally by the servers or not part of the APIs. These constants
are free to evolve without breaking compatibilities. For example, {{MAX_PATH_LENGTH}} is used
by the NN to enforce the length of the path does not go too long. Developers are free to change
the name of the constants and to move it around if necessary.
> 1. Constants that are used by the clients, but not parts of the APIs. For example, {{QUOTA_DONT_SET}}
represents an unlimited quota. The value is part of the wire protocol but the value is not.
Developers are free to rename the constants but are not allowed to change the value of the
constants.
> 1. Constants that are parts of the APIs. For example, {{SafeModeAction}} is used in {{DistributedFileSystem}}.
Changing the name / value of the constant will break binary compatibility, but not source
code compatibility.
> This jira proposes to separate the above three types of constants into different classes:
> * Creating a new class {{HdfsConstantsServer}} to hold the first type of constants.
> * Move {{HdfsConstants}} into the {{hdfs-client}} package. The work of separating the
second and the third types of constants will be postponed in a separate jira.



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