Jason Gustafson created KAFKA-12286:
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Summary: Consider storage/cpu tradeoff in metadata record framing
schema
Key: KAFKA-12286
URL: https://issues.apache.org/jira/browse/KAFKA-12286
Project: Kafka
Issue Type: Improvement
Reporter: Jason Gustafson
KIP-631 calls for unsigned varints in order to represent the api key and
version. We are also adding a frame version, which will be unsigned varint. The
use of the varint means we can save a byte from each of these fields compared
to an int16. The downside is that it is that the serialization is a little more
expensive. For varints, we typically require one call to compute the size of
the field and a separate call to actually write it. If this becomes an issue,
there are a couple options:
1. We can use the int16 and pay the extra 3 bytes.
2. We can let the generated classes compute the encoded api key and version as
a byte and fail if we ever exceed the range of varint that can fit in a single
byte. This would let us replace `writeUnsignedVarint` with `writeByte`.
The second option seems reasonable to me. I think it's extremely unlikely we'll
ever need more than a byte for either the api key or the version. At least it
should be years before that happens and we will have options to deal with it if
it does.
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