rpma_send_with_imm(3)

💖 rpma_send_with_imm — RPMA Programmer's Manual 💖

okay bestie, pull up a chair, we're doing librpma today and this one is genuinely so fun. it's rpma_send_with_imm(3), and no, the manual name isn't a typo, it's literally the function name, slay. ✨

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🌸 NAME 🌸

rpma_send_with_imm — initiate the send operation with immediate data 🫶

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✨ SYNOPSIS ✨

#include <librpma.h>

struct rpma_conn;
struct rpma_mr_local;
int rpma_send_with_imm(struct rpma_conn *conn, const struct rpma_mr_local *src,
                size_t offset, size_t len, int flags, uint32_t imm,
                const void *op_context);

like, look at that signature. it's giving main character energy and we love her for it. 💅

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🦋 DESCRIPTION 🦋

so rpma_send_with_imm() kicks off the send operation with immediate data, which means it transfers a message from your local memory over to the other side of the connection. sending a lil message across the wire. iconic behavior honestly. 🌈

now here's a cute edge case: if you wanna send a 0 byte message, set src to NULL and set both offset and len to 0. yes, both. not one. both. 🎀

the flags attribute is what sets the completion notification indicator, and you get to pick:

• RPMA_F_COMPLETION_ON_ERROR — generate the completion on error (aka only ping me when things go sideways 😭)
• RPMA_F_COMPLETION_ALWAYS — generate the completion regardless of result of the operation (aka ping me no matter what, I wanna know everything 👑)

and op_context? that little baby gets returned in the wr_id field of the completion (struct ibv_wc). so you can pass whatever you want through and it comes right back to you. it's giving boomerang. 🪃✨

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💜 RETURN VALUE 💜

rpma_send_with_imm() returns 0 on success, or a negative error code on failure. no in-between, no drama. 💀

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🌺 ERRORS 🌺

rpma_send_with_imm() can fail with the following errors, and ngl you will meet some of these:

• RPMA_E_INVAL — conn == NULL || flags == 0 (you forgot the conn or you passed no flags at all, bestie 😭)
• RPMA_E_INVAL — src == NULL && (offset != 0 || len != 0) (you said "empty message" but then gave me an offset or a len, pick a lane 🙈)
• RPMA_E_PROVIDER — ibv_post_send(3) failed (not us, the provider underneath, fr fr)

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🎀 SEE ALSO 🎀

rpma_conn_req_connect(3), rpma_mr_reg(3), librpma(7) and https://pmem.io/rpma/

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reminder bestie: that second RPMA_E_INVAL is the sneaky one. if src is NULL, then offset and len have to be 0, or she's gonna yell at you. 🫶

okay that's the whole page, you ate that. this has been the RPMA manual, 01 April 2024 edition, brought to you by the RPMA Programmer's Manual — go forth and send with immediate data, periodt. 💅🌸✨