io_uring_sqe_set_data(3)

✨ io_uring_sqe_set_data — bestie, let's label your requests ✨

okay so this is a page from the liburing Manual (yes, the io_uring girlies stay winning) 💖

🌸 NAME 🌸

io_uring_sqe_set_data — set user data for submission queue event

🎀 SYNOPSIS 🎀

#include <liburing.h>

void io_uring_sqe_set_data(struct io_uring_sqe *sqe,
                           void *user_data);

void io_uring_sqe_set_data64(struct io_uring_sqe *sqe,
                             __u64 data);

🦋 DESCRIPTION 🦋

so. picture this. you've got a submission queue entry, and it's just sitting there, anonymous, no identity, no lore. tragic. 😭

The io_uring_sqe_set_data(3) function stores a user_data pointer with the submission queue entry sqe.

The io_uring_sqe_set_data64(3) function stores a 64-bit data value with the submission queue entry sqe.

After the caller has requested a submission queue entry (SQE) with io_uring_get_sqe(3), they can associate a data pointer or value with the SQE. Once the completion arrives, the function io_uring_cqe_get_data(3) or io_uring_cqe_get_data64(3) can be called to retrieve the data pointer or value associated with the submitted request. it's giving "tag it so you can find it again" energy, and honestly? iconic. 🫶

⚠️ no cap, this is the part you have to read: note that if neither of these functions are called, or the user_data field in the sqe isn't set manually either, then the field may contain a value from a previous use of this sqe. If an application relies on always having a valid user_data value present, it must always assign one to each sqe. like, every single time. no skipping. the stale-data jumpscare is real 💀

🌈 RETURN VALUE 🌈

None. that's it, that's the whole section, she returns nothing and she's thriving 💅

👑 SEE ALSO 👑

• io_uring_get_sqe(3)
• io_uring_cqe_get_data(3)

and that's the whole page bestie!! this one came from liburing-2.1, dated November 15, 2021, and it lives at io_uring_sqe_set_data(3) 🎀✨ go set your data and slay 💜