Hey, I'm a Software Engineer on Proxygen as well. Proxygen heavily relies on folly's buffer management abstractions such as IOBuf (https://github.com/facebook/folly/blob/master/folly/io/IOBuf...) and Cursor (https://github.com/facebook/folly/blob/master/folly/io/Curso...). Protocol parsing implementation uses folly::io::Cursor to safely read byte sequences across non-contiguous buffers. Errors during parsing are wrapped up in Result types (https://github.com/facebook/proxygen/blob/master/proxygen/li...) which take an inspiration from Rust. Such constructs simplify our implementation to a reasonable extent and are still low-level enough to extract performance.