Binary serialisation of Rust data strucutures [closed]

Question

What is the current state of serialisation-to-binary in Rust?

I have some large (1-10MB) data structure to be sent across a network, and don't want to encode them as JSON or hex (the two serialisers I have found).

I have found #[repr(packed)]. Is this what I should use, or is there something more portable?

Answer 1

#[repr(packed)] only makes your data small. It does not offer any format guarantees or serialization help.

You have a few choices here (ordered by my opinion from best to worst solution):

1. You can use the Cap'n proto implementation for Rust
   • https://github.com/dwrensha/capnproto-rust
   • It's not really serialization, more of a forced format for structs that are then sent over the network without any conversion
   • fast
2. You could write your own Serializer and Deserializer.
   • you have full control over the format
   • runtime overhead for every single datum
   • you need to implement lots of stuff
3. You can transmute your structs to a [u8] and send that
   • probably the fastest solution
   • you need to make sure that the compiler for the program on both sides is exactly the same, otherwise the formats don't match up.
   • Someone evil may send you bad data. When you transmute that back, you get buffer overflows and stuff
   • references in your data-structure will cause wild pointers and undefined behaviour
     • Don't use references