I build the Rust core of a self-custody wallet and rebuild the layer underneath from scratch — databases, TCP servers, storage engines — to understand how the real ones work. This is where I write it down.https://valentynkit.com/https://valentynkit.com/blog/framework-knowledge-evaporates/https://valentynkit.com/blog/framework-knowledge-evaporates/I learned async three times before it clicked. Building a TCP echo server from blocking sockets up through kqueue and epoll in C, seven times, is what finally fixed it.Thu, 25 Jun 2026 00:00:00 GMThttps://valentynkit.com/blog/from-blocking-accept-to-epoll/https://valentynkit.com/blog/from-blocking-accept-to-epoll/Building a TCP echo server in C seven times, from blocking through select, poll, kqueue, and epoll, with the cost of each wall measured: a 1.5 second stall, a pegged core, the FD_SETSIZE ceiling, and O(ready) dispatch.Tue, 30 Jun 2026 00:00:00 GMT