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https://issues.apache.org/jira/browse/HBASE-11660?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14084891#comment-14084891
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Eric Hanson commented on HBASE-11660:
-------------------------------------
The existing WAL reading code appears to take a hard dependency on the behavior
of the available method in DFSInputStream.java, which looks like this in the
Hadoop trunk:
{code}
/** Return the size of the remaining available bytes
* if the size is less than or equal to {@link Integer#MAX_VALUE},
* otherwise, return {@link Integer#MAX_VALUE}.
*/
@Override
public synchronized int available() throws IOException {
if (closed) {
throw new IOException("Stream closed");
}
final long remaining = getFileLength() - pos;
return remaining <= Integer.MAX_VALUE? (int)remaining: Integer.MAX_VALUE;
}
{code}
This implied contract is different from the one in java.io.InputStream.
> Make WAL reader follow contract for java.io.InputStream.available()
> -------------------------------------------------------------------
>
> Key: HBASE-11660
> URL: https://issues.apache.org/jira/browse/HBASE-11660
> Project: HBase
> Issue Type: Bug
> Components: wal
> Reporter: Eric Hanson
> Priority: Minor
> Attachments: hbase-11660.01.patch
>
>
> In the process of building support to running HBase on Microsoft Azure
> HDInsight, I hit an issue in the HBase WAL reading process that took a lot of
> time to debug. The WAL reading code depends on available() for the log
> InputStream never returing 0 until end of file. This is not the same as the
> contract in java.io.InputStream for available.
> To prevent future grief for others that may want to port HBase onto storage
> systems other than HDFS, I propose to change the HBase WAL reader so it does
> not assume that EOF has been reached when available() == 0. It instead would
> treat available only as described in InputStream, i.e. available() is merely
> the number of bytes that could be read from the stream without blocking. That
> could be 0 even before EOF.
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