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https://issues.apache.org/jira/browse/CASSANDRA-15410?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16974417#comment-16974417
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Yifan Cai commented on CASSANDRA-15410:
---------------------------------------

[~aleksey] thanks for reviewing. 

Understood the concern here. It assumes the method is/will be only used in the 
scenarios such as encoding message.

We can have a separate method that explicitly takes the argument of reserved 
size, if encodeSize is a strong constraint and correct for message 
serialization, so it can be relied on. There is a big performance difference 
calculating the size and skipping calculation. Especially for the long strings, 
the time taken of the prior is 2x than the latter one.

> Avoid over-allocation of bytes for UTF8 string serialization 
> -------------------------------------------------------------
>
>                 Key: CASSANDRA-15410
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-15410
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Messaging/Client
>            Reporter: Yifan Cai
>            Assignee: Yifan Cai
>            Priority: Normal
>             Fix For: 4.0
>
>
> In the current message encoding implementation, it first calculates the 
> `encodeSize` and allocates the bytebuffer with that size. 
> However, during encoding, it assumes the worst case of writing UTF8 string to 
> allocate bytes, i.e. assuming each letter takes 3 bytes. 
> The over-estimation further leads to resizing the underlying array and data 
> copy. 



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