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https://issues.apache.org/jira/browse/CASSANDRA-1788?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Brandon Williams updated CASSANDRA-1788:
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Attachment: 1788-v7.txt
v7 is rebased to apply to current trunk. It magically has no problems now, but
I didn't change anything.
> reduce copies on read, write paths
> ----------------------------------
>
> Key: CASSANDRA-1788
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1788
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Jonathan Ellis
> Assignee: Jonathan Ellis
> Priority: Minor
> Fix For: 1.0
>
> Attachments: 0001-setup.txt,
> 0002-remove-copies-from-network-path.txt, 1788-v2.txt, 1788-v3.txt,
> 1788-v4.txt, 1788-v6.txt, 1788-v7.txt, 1788.txt
>
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> Currently, we do _three_ unnecessary copies (that is, writing to the socket
> is necessary; any other copies made are overhead) for each message:
> - constructing the Message body byte[] (this is typically a call to a
> ICompactSerializer[2] serialize method, but sometimes we cheat e.g. in
> SchemaCheckVerbHandler's reply)
> - which is copied to a buffer containing the entire Message (i.e. including
> Header) when sendOneWay calls Message.serializer.serialize()
> - which is copied to a newly-allocated ByteBuffer when sendOneWay calls packIt
> - which is what we write to the socket
> For deserialize we perform a similar orgy of copies:
> - IncomingTcpConnection reads the Message length, allocates a byte[], and
> reads the serialized Message into it
> - ITcpC then calls Message.serializer().deserialize, which allocates a new
> byte[] for the body and copies that part
> - finally, the verbHandler (determined by the now-deserialized Message
> header) deserializes the actual object represented by the body
> Most of these are out of scope for 0.7 but I think we can at least elide the
> last copy on the write path and the first on the read.
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