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https://issues.apache.org/jira/browse/HDFS-1799?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13029236#comment-13029236
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Ivan Kelly commented on HDFS-1799:
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I much prefer the interface for JournalManager, though you should change open()
to createStream().
I don't see the need for JournalAndStream. You never need to get the
JournalManager if you have a stream or vice versa. So why couple them? Your
design from the 29th April doesn't couple them, and I think the failure
mechanism from that is quite elegant. To restate it, so I understood it
correctly...
FSEditLog has a list of JournalManagers and ELOS. On initJournals, the ELOS
list is populated from the JournalManagers. If a failure occurs, the ELOS is
simply dropped. Then on beginRoll, ELOS is cleared and repopulated from the
JournalManagers (this will readd any failed journal which is once again
available).
Since a mapping between JournalManagers and ELOS is unnecessary, why add it?
> 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-alternate-design.txt, 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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