Reusing Buffers in Multicore OCaml

OCaml is a pragmatic functional language. You can do very advanced things with its type system (like an entire roguelike), and you can also hide the traditional buffer management techniques of C behind a nice abstract interface. One of those techniques stopped being safe when OCaml became multicore; I've hit it in ocaml-wire last week. ocaml-wire is the codec layer of Parsimoni's space protocol stack; its decode path runs for every packet, so it should be safe and fast (and ideally, work with multiple domains!). Validators ocaml-wire implements EverParse's model of binary formats. EverParse is Project Everest's verified parser generator: a format description carries its own validity constraints, and the generated validator rejects malformed input before any application code sees it. The library keeps that shape in OCaml, and can emit .3d files when formally verified C parsers are needed. For instance, take a record of three 16-bit fields x, y and z whose last field must be the sum of…