The Tokio Upgrade From 0.2 to 1.x

The Rust ecosystem has recently seen a major upgrade from version 0.2 to 1.0 of the Tokio library, which is used by many projects including Fly.io's load-balancer. This upgrade involved several changes such as removal of Stream implementations until its stabilization in stdlib, relaxed mutable access requirements, new AsyncRead and AsyncWrite traits, more Pinning required for Futures like Sleep and Shutdown, absence of block_on from runtime::Handle, TcpListener needing to be set non-blocking, and miscellaneous API changes. Despite these changes, the upgrade was not difficult due to good coordination by the Tokio team and helpful resources such as the Tokio Discord channel.