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https://issues.apache.org/jira/browse/HBASE-5878?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14681980#comment-14681980
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Nick Dimiduk commented on HBASE-5878:
-------------------------------------
Thanks [~apurtell] and [~ashish singhi]!
> Use getVisibleLength public api from HdfsDataInputStream from Hadoop-2.
> -----------------------------------------------------------------------
>
> Key: HBASE-5878
> URL: https://issues.apache.org/jira/browse/HBASE-5878
> Project: HBase
> Issue Type: Bug
> Components: wal
> Reporter: Uma Maheswara Rao G
> Assignee: Ashish Singhi
> Fix For: 2.0.0, 0.98.14, 1.0.2, 1.2.0, 1.1.2, 1.3.0
>
> Attachments: HBASE-5878-branch-1.0.patch, HBASE-5878-v2.patch,
> HBASE-5878-v3.patch, HBASE-5878-v4.patch, HBASE-5878-v5-0.98.patch,
> HBASE-5878-v5.patch, HBASE-5878-v5.patch, HBASE-5878-v6-0.98.patch,
> HBASE-5878-v6.patch, HBASE-5878-v7-0.98.patch, HBASE-5878.patch
>
>
> SequencFileLogReader:
> Currently Hbase using getFileLength api from DFSInputStream class by
> reflection. DFSInputStream is not exposed as public. So, this may change in
> future. Now HDFS exposed HdfsDataInputStream as public API.
> We can make use of it, when we are not able to find the getFileLength api
> from DFSInputStream as a else condition. So, that we will not have any sudden
> surprise like we are facing today.
> Also, it is just logging one warn message and proceeding if it throws any
> exception while getting the length. I think we can re-throw the exception
> because there is no point in continuing with dataloss.
> {code}
> long adjust = 0;
> try {
> Field fIn = FilterInputStream.class.getDeclaredField("in");
> fIn.setAccessible(true);
> Object realIn = fIn.get(this.in);
> // In hadoop 0.22, DFSInputStream is a standalone class. Before
> this,
> // it was an inner class of DFSClient.
> if (realIn.getClass().getName().endsWith("DFSInputStream")) {
> Method getFileLength = realIn.getClass().
> getDeclaredMethod("getFileLength", new Class<?> []{});
> getFileLength.setAccessible(true);
> long realLength = ((Long)getFileLength.
> invoke(realIn, new Object []{})).longValue();
> assert(realLength >= this.length);
> adjust = realLength - this.length;
> } else {
> LOG.info("Input stream class: " + realIn.getClass().getName() +
> ", not adjusting length");
> }
> } catch(Exception e) {
> SequenceFileLogReader.LOG.warn(
> "Error while trying to get accurate file length. " +
> "Truncation / data loss may occur if RegionServers die.", e);
> }
> return adjust + super.getPos();
> {code}
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