# MoldUDP64 Client for Rust
A blazingly fast [MoldUDP64](https://www.nasdaqtrader.com/content/technicalsupport/specifications/dataproducts/moldudp64.pdf) client in Rust.
## Features
- Automatically re-requests dropped/ missing packets
- Multiple re-request servers
- Automatically retries failed re-requests with configurable limit.
- Lock free
- ZERO hot path allocations
- Allocation free data structures to inspect packets.
## Usage
`cargo add moldudp`
```rust
use std::net::{Ipv4Addr, SocketAddr, SocketAddrV4};
use moldudp::{MoldUDP64,Packet};
let rx = MoldUDP64::builder()
// Multicast group + port carrying the live downstream feed.
.multicast_addr(SocketAddrV4::new(Ipv4Addr::new(233, 252, 0, 1), 30001))
// Local NIC to join on. Use `UNSPECIFIED` to let the OS pick.
.interface_addr(Ipv4Addr::UNSPECIFIED)
// One or more re-request servers. The client load-balances requests
// across them and merges responses back into the same stream.
.rerequest_server_addrs(vec![
SocketAddr::from(([10, 0, 0, 1], 30002)),
SocketAddr::from(([10, 0, 0, 2], 30002)),
])
// Optional: pin the expected session. If set, packets from any other
// session ident are dropped. If omitted, the client locks onto the
// first session it sees.
.expected_session_ident("0123456789".to_string())
// Optional: starting sequence number. Defaults to 1 (the start of
// the session) if omitted; gaps before this point are not requested.
.expected_seq_num(1)
.build()
.start()?;
// Datagrams arrive in receive order — live and retransmitted packets are
// interleaved. The consumer is responsible for ordering by seq num.
// Minimal validation is done on datagrams, only that they are at least
// 20 bytes in length.
while let Ok(datagram) = rx.recv() {
// Use [`moldudp::Packet`] to construct a 0 allocation view on the bytes.
let packet = Packet::new(packet);
handle(packet);
}
```