rpma_atomic_write(3)

💖 rpma_atomic_write(3) 💖

okay bestie, so this is from the RPMA Programmer's Manual and it's literally the whole tea on rpma_atomic_write — one function, eight little bytes, maximum drama. sit down, hydrate, let's go ✨

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🌸 NAME 🌸

rpma_atomic_write — initiate the atomic 8 bytes write operation

like. it writes 8 bytes. atomically. that's the vibe. periodt 💅

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🎀 SYNOPSIS 🎀

#include <librpma.h>

struct rpma_conn;
struct rpma_mr_remote;
int rpma_atomic_write(struct rpma_conn *conn,
                struct rpma_mr_remote *dst, size_t dst_offset,
                const char src[8], int flags, const void *op_context);

she's giving forward declarations and one very specific little signature 🦋 no cap, copy it exactly.

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✨ DESCRIPTION ✨

so rpma_atomic_write() initiates the atomic 8 bytes write operation — that's moving data from the local memory over to the remote memory. and the way this one works? it transfers exactly 8 bytes of data and stores them atomically in the remote memory. not 7, not 9. eight. iconic behaviour honestly 🔥

the attribute flags set the completion notification indicator:

• RPMA_F_COMPLETION_ON_ERROR — generate the completion on error
• RPMA_F_COMPLETION_ALWAYS — generate the completion regardless of result of the operation.

and op_context? she gets returned in the wr_id field of the completion (which is a struct ibv_wc). so you hand her something cute, and she hands it right back through the completion. we love a round trip 💖

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👑 RETURN VALUE 👑

rpma_atomic_write() returns 0 on success or a negative error code on failure. simple as that, bestie.

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💀 ERRORS 💀

rpma_atomic_write() can fail with the following errors:

• RPMA_E_INVAL — conn, dst or src is NULL
• RPMA_E_INVAL — dst_offset is not aligned to 8 bytes
• RPMA_E_INVAL — flags are not set (flags == 0)
• RPMA_E_PROVIDER — ibv_post_send(3) failed

okay so real talk, the alignment one is not a suggestion. dst_offset has to be aligned to 8 bytes or she WILL hit you with RPMA_E_INVAL. no flagging, no half-vibes, no flags == 0. got it? got it 🫶

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🌈 SEE ALSO 🌈

• rpma_conn_req_connect(3)
• rpma_mr_reg(3)
• rpma_mr_remote_from_descriptor(3)
• librpma(7)
• https://pmem.io/rpma/

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and that's the whole page, bestie ✨ this one's from RPMA, dated 01 April 2024, and it lives at rpma_atomic_write(3) — go forth and write exactly 8 bytes, atomically, like the main character you are 💜🧚🌸