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https://issues.apache.org/jira/browse/CASSANDRA-14556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16543835#comment-16543835
 ] 

ASF GitHub Bot commented on CASSANDRA-14556:
--------------------------------------------

Github user dineshjoshi commented on a diff in the pull request:

    https://github.com/apache/cassandra/pull/239#discussion_r202489810
  
    --- Diff: 
src/java/org/apache/cassandra/net/async/RebufferingByteBufDataInputPlus.java ---
    @@ -249,4 +250,42 @@ public ByteBufAllocator getAllocator()
         {
             return channelConfig.getAllocator();
         }
    +
    +    /**
    +     * Consumes bytes in the stream until the given length
    +     *
    +     * @param writer
    +     * @param len
    +     * @return
    +     * @throws IOException
    +     */
    +    public long consumeUntil(BufferedDataOutputStreamPlus writer, long 
len) throws IOException
    +    {
    +        long copied = 0; // number of bytes copied
    +        while (copied < len)
    +        {
    +            if (buffer.remaining() == 0)
    +            {
    +                try
    +                {
    +                    reBuffer();
    +                }
    +                catch (EOFException e)
    +                {
    +                    throw new EOFException("EOF after " + copied + " bytes 
out of " + len);
    +                }
    +                if (buffer.remaining() == 0)
    +                    return copied == 0 ? -1 : copied;
    --- End diff --
    
    Re-reading the code, the check on [line 
227](https://github.com/dineshjoshi/cassandra/blob/f9573ccef63535b787e91e46fa886f3e3ff2eee8/src/java/org/apache/cassandra/net/async/RebufferingByteBufDataInputPlus.java#L277)
 is just being over cautious in case the `reBuffer` implementation changes and 
can return a empty buffer.


> Optimize streaming path in Cassandra
> ------------------------------------
>
>                 Key: CASSANDRA-14556
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14556
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Streaming and Messaging
>            Reporter: Dinesh Joshi
>            Assignee: Dinesh Joshi
>            Priority: Major
>              Labels: Performance
>             Fix For: 4.x
>
>
> During streaming, Cassandra reifies the sstables into objects. This creates 
> unnecessary garbage and slows down the whole streaming process as some 
> sstables can be transferred as a whole file rather than individual 
> partitions. The objective of the ticket is to detect when a whole sstable can 
> be transferred and skip the object reification. We can also use a zero-copy 
> path to avoid bringing data into user-space on both sending and receiving 
> side.



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