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From "Ivan Kelly (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-1799) Refactor log rolling and filename management out of FSEditLog
Date Tue, 03 May 2011 09:57:03 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1799?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13028133#comment-13028133
] 

Ivan Kelly commented on HDFS-1799:
----------------------------------

{quote}
In any case, HDFS-1580 also adds an additional class here so that point seems mute.
{quote}
HDFS-1580 adds the JournalFactory class to provide a single point of pluggability. It is purely
a factory that exists for the creation of different types of streams and then goes away so
the point is not moot.

In this case where there's only one type of OutputStream used, JournalFactory is not even
necessary. EditLogFileOutputStream could be created directly.

{quote}
Do you think the code and data for managing the lifecycle of logs/ledgers should not be logically
grouped?
{quote}
I don't know what you mean by data, but of course it should be logically grouped. I'm not
arguing about that. I'm arguing about how the logic is being grouped.

{quote}
    I really don't like the call to getCurrentStream() having to be called every time you
want an output stream. 

Why? Can you be more specific?
{quote}
I don't like it because the currentStream will never change without FSEditLog telling it to
change (through divert/revert, startLogSegment/endLogSegment later). So why doesn't FSEditLog
just get a new reference to the currentStream once it has told it to change? 

> Refactor log rolling and filename management out of FSEditLog
> -------------------------------------------------------------
>
>                 Key: HDFS-1799
>                 URL: https://issues.apache.org/jira/browse/HDFS-1799
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>    Affects Versions: Edit log branch (HDFS-1073)
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>             Fix For: Edit log branch (HDFS-1073)
>
>         Attachments: 0001-Added-state-management-to-FSEditLog.patch, 0002-Standardised-error-pattern.patch,
0003-Add-JournalFactory-and-move-divert-revert-out-of-FSE.patch, HDFS-1799-all.diff, hdfs-1799.txt,
hdfs-1799.txt, hdfs-1799.txt, hdfs-1799.txt
>
>
> This is somewhat similar to HDFS-1580, but less ambitious. While that JIRA focuses on
pluggability, this task is simply the minimum needed for HDFS-1073:
> - Refactor the filename-specific code for rolling, diverting, and reverting log streams
out of FSEditLog into a new class
> - Clean up the related code in FSEditLog a bit
> Notably, this JIRA is going to temporarily break the BackupNode. I plan to circle back
on the BackupNode later on this branch.

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