Max IndenWe replaced @mozilla Firefox’s QUIC UDP I/O stack with a modern memory-safe implementation using quinn-udp. Instead of limited and dated system calls like sendto and recvfrom, Firefox now uses modern OS specific system calls across all major platforms, resulting in HTTP/3 QUIC throughput improvements when CPU bound, and enabling QUIC ECN support across all major platforms.
Fast UDP I/O for Firefox in Rust
Motivation Around 20% of Firefox’s HTTP traffic today uses HTTP/3, which runs over QUIC, which in turn runs over UDP. This translates to substantial UDP I/O activity. Firefox uses NSPR for most of its network I/O. When it comes to UDP I/O, NSPR only offers a limited set of dated APIs, most relevant here PR_SendTo and PR_RecvFrom, wrappers around POSIX’s sendto and recvfrom. The N in NSPR stands for Netscape, giving you a hint of its age.