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https://issues.apache.org/jira/browse/HDFS-1580?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13003127#comment-13003127
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Ivan Kelly commented on HDFS-1580:
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To read in a log you pass in a URI to the getInputStream method. For BK, this
will allow us to have no explicit transfer stage. Files are a different matter.
I haven't thought much about it yet, but file URI do have a space for host.
file://<host>/<path>. The FileJournalManager could return a URI with the host
part set for getLogs. This could be passed to the getInputStream call, which
would download it from the remote host if nescessary.
So, the steps would be as you outlined except for the "iterates over each of
the RemoteLogs, and fetches them". Instead you would just iterate over them and
load them using the JournalManager.getInputStream method. The implementation of
the method would take care of whether the file is remote or local.
> Add interface for generic Write Ahead Logging mechanisms
> --------------------------------------------------------
>
> Key: HDFS-1580
> URL: https://issues.apache.org/jira/browse/HDFS-1580
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Ivan Kelly
> Attachments: HDFS-1580+1521.diff, HDFS-1580.diff,
> generic_wal_iface.pdf, generic_wal_iface.pdf, generic_wal_iface.txt
>
>
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