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https://issues.apache.org/jira/browse/HDFS-2003?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13043420#comment-13043420
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Ivan Kelly commented on HDFS-2003:
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{quote}
>From the perspective of FSEditLogLoader, an EOFException while reading the
>opcode (expected) is treated the same as an EOFException in the middle of
>reading one of the ops (unexpected). This seems unintentional, since a
>truncated log file is not normal, right?
{quote}
This is intentional. We read from the journal which has the most edits
available to read. If this happens to be a journal with a truncated file, that
journal is still the journal with the most up to date logs. Do you disagree?
{quote}
I'm thinking it might be slightly cleaner to make a new class like
FSEditLogReader, which is instantiated with an InputStream and logVersion. It
would then expose just a readOp() method. I think that will make it easier to
mock up sources of edits in the future. What do you think?
{quote}
Makes sense.
> Separate FSEditLog reading logic from editLog memory state building logic
> -------------------------------------------------------------------------
>
> Key: HDFS-2003
> URL: https://issues.apache.org/jira/browse/HDFS-2003
> Project: Hadoop HDFS
> Issue Type: Improvement
> Affects Versions: Edit log branch (HDFS-1073)
> Reporter: Ivan Kelly
> Assignee: Ivan Kelly
> Fix For: Edit log branch (HDFS-1073)
>
> Attachments: HDFS-2003.diff, HDFS-2003.diff
>
>
> Currently FSEditLogLoader has code for reading from an InputStream
> interleaved with code which updates the FSNameSystem and FSDirectory. This
> makes it difficult to read an edit log without having a whole load of other
> object initialised, which is problematic if you want to do things like count
> how many transactions are in a file etc.
> This patch separates the reading of the stream and the building of the memory
> state.
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