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https://issues.apache.org/jira/browse/CASSANDRA-12838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15610435#comment-15610435
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Stefania commented on CASSANDRA-12838:
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I opted for something much simpler for extending the QUERY flags, because the
response flags are already encoded as {{\[int\]}}, not {{\[byte\]}}, and vints
would have changed the formats of response messages. Since we have to break the
format anyway, I opted to extend the query flags from {{\[byte\]}} to
{{\[int\]}} as well. This gives us plenty of room for more flags in the future,
and the couple of extra bytes on the wire for each message do not justify the
complexity of vint encoding. Let's leave this complexity to where it is
justified, that is ints and longs that are sent back as result data.
I've created the 3.X patch, because the refactoring of the protocol version is
quite large, I would like to finalize the review before porting it on trunk:
||3.X||
|[patch|https://github.com/stef1927/cassandra/tree/12838-3.X]|
|[testall|http://cassci.datastax.com/view/Dev/view/stef1927/job/stef1927-12838-3.X-testall/]|
|[dtest|http://cassci.datastax.com/view/Dev/view/stef1927/job/stef1927-12838-3.X-dtest/]|
[~blerer]: ready for review.
[~aholmber]: the python driver changes are
[here|https://github.com/datastax/python-driver/compare/master...stef1927:12838]
(untested). The java driver doesn't support v5 yet as far as I could see, so I
did not prepare a patch for it.
> Extend native protocol flags and add supported versions to the SUPPORTED
> response
> ---------------------------------------------------------------------------------
>
> Key: CASSANDRA-12838
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12838
> Project: Cassandra
> Issue Type: Sub-task
> Components: CQL
> Reporter: Stefania
> Assignee: Stefania
> Fix For: 3.x
>
>
> We already use 7 bits for the flags of the QUERY message, and since they are
> encoded with a fixed size byte, we may be forced to change the structure of
> the message soon, and I'd like to do this in version 5 but without wasting
> bytes on the wire. Therefore, I propose to convert fixed flag's bytes to
> unsigned vints, as defined in CASSANDRA-9499. The only exception would be the
> flags in the frame, which should stay as fixed size.
> Up to 7 bits, vints are encoded the same as bytes are, so no immediate change
> would be required in the drivers, although they should plan to support vint
> flags if supporting version 5. Moving forward, when a new flag is required
> for the QUERY message, and eventually when other flags reach 8 bits in other
> messages too, the flag's bitmaps would be automatically encoded with a size
> that is big enough to accommodate all flags, but no bigger than required. We
> can currently support up to 8 bytes with unsigned vints.
> The downside is that drivers need to implement unsigned vint encoding for
> version 5, but this is already required by CASSANDRA-11873, and will most
> likely be required by CASSANDRA-11622 as well.
> I would also like to add the list of versions to the SUPPORTED message, in
> order to simplify the handshake for drivers that prefer to send an OPTION
> message, rather than rely on receiving an error for an unsupported version in
> the STARTUP message. Said error should also contain the full list of
> supported versions, not just the min and max, for clarity, and because the
> latest version is now a beta version.
> Finally, we currently store versions as integer constants in {{Server.java}},
> and we still have a fair bit of hard-coded numbers in the code, especially in
> tests. I plan to clean this up by introducing a {{ProtocolVersion}} enum.
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