[zigzag312]

It looks similar to how vint64 lib encodes varints. Total length of varint can be determined via the first byte alone.

[haberman]

I advocated for PrefixVarint (which seems equivalent to vint64 ) for WebAssembly, but it was decided against, in favor of LEB128: https://github.com/WebAssembly/design/issues/601

The recent CREL format for ELF also uses the more established LEB128: https://news.ycombinator.com/item?id=41222021

At this point I don't feel like I have a clear opinion about whether PrefixVarint is worth it, compared with LEB128.

[zigzag312]

Just remember that XML was more established than JSON for a long time.

[kannanvijayan]

Varint encoding is something I've peeked at in various contexts. My personal bias is towards the prefix-style, as it feels faster to decode and the segregation of the meta-data from the payload data is nice.

But, the thing that tends to tip the scales is the fact that in almost all real world cases, small numbers dominate - as the github thread you linked relates in a comment.

The LEB128 fast-path is a single conditional with no data-dependencies:

  if ! (x & 0x80) { x }

Modern CPUs will characterize that branch really well and you'll pay almost zero cost for the fastpath which also happens to be the dominant path.

It's hard to beat.

[yencabulator]

SQLite format equivalent:

  if x <= 240 { x }

while strictly improving all other aspects (at least IMHO)

https://sqlite.org/src4/doc/trunk/www/varint.wiki