io_setcookie(3)

💖 NAME 💖

okay bestie, this is io_setcookie(3) from the Library Functions Manual. The name says it all: io_setcookie — associate cookie with descriptor. ✨

✨ SYNTAX ✨

#include <libowfat/io.h>

void io_setcookie(int64 fd,void* cookie);

🍓 DESCRIPTION 🍓

so io_setcookie is giving “attach a cookie to this descriptor.” And by cookie we mean a pointer to some anonymous data structure — not a snack, sadly. You can only have one cookie associated with a descriptor. One descriptor, one cookie, periodt. 💅

When you wanna retrieve that cookie for a descriptor, you use io_getcookie(3) — usually right after io_canread or io_canwrite brought it to your attention. Like, “hey bestie, this fd is ready,” and you’re like “say less, lemme grab my cookie.” 🍪

⚠️ important caveat, no cap: io_close does not deallocate your cookie. Not even a little. You need to do that yourself. The library is not your mom. 😭

The whole idea is iconic: you put the state associated with a TCP connection you serve into a common struct. Then you do not need to have your own data structure to retrieve the state for a connection — you can just use the data structure io_wait already maintains. The lookup works in constant time and should not cause any cache misses. It’s giving efficient, it’s giving main character energy. 👑

🌈 SEE ALSO 🌈

• io_wait(3)
• io_getcookie(3)

— io_setcookie(3) from the Library Functions Manual. The footer is just the page title, no source, version, or date listed, so that’s the whole sign-off vibe. Mwah 💋🦋