Protobuf Parser

This directory contains a seastar friendly protobuf parser. It should adhere to the same compatibility guarantees as the offical C++ library but has a few notable differences:

1. Does not make contiguous allocations of repeated fields, maps or strings/bytes types
2. Is reactor friendly on deeply nested or large protobufs in that it will yield control
3. Is a stackless parser, so it is not bound by the smallish 1MB stacks that seastar uses for threads

Development

If you are tasked with updating this code, here are a few helpful links:

1. Encoding spec (note this elides some important details about how invalid/corrupted data is handled)
2. Golang protobuf parser
3. Java protobuf parser
4. C++ protobuf parser
5. Protobuf Zero