SHMEM_LONGLONG_FINC(3)

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version 5.0.10 · 4 versions

💖 SHMEM_LONGLONG_FINC(3) 💖

ok so bestie. welcome to the Open MPI section 3 manual, and today's main character is a whole family of fetch-and-increment girlies: shmem_int4_finc(3), shmem_int8_finc(3), shmem_int_finc(3), shmem_long_finc(3), and shmem_longlong_finc(3). together they perform an atomic fetch-and-increment operation on a remote data object. no cap. so iconic of them.

✨ SYNOPSIS ✨

🌸 C or C++

#include <mpp/shmem.h>

int shmem_int_finc(int *target, int pe)

long shmem_long_finc(long *target, int pe)

long long shmem_longlong_finc(long long *target, int pe)

🦋 Fortran

INCLUDE "mpp/shmem.fh"

INTEGER pe
INTEGER(KIND=4) SHMEM_INT4_FINC, target4
INTEGER(KIND=8) SHMEM_INT8_FINC, target8

ires4 = SHMEM_INT4_FINC(target4, pe)

ires8 = SHMEM_INT8_FINC(target8, pe)

💅 DESCRIPTION 💅

ok so the fetch and increment routines are giving very specific energy: they grab the value sitting at address target on PE pe, and then they update target with the result of incrementing that retrieved value by one. yes, both. the fetch and the increment. she does it all 💅

and the way that this must be completed without the possibility of another process updating target between the time of the fetch and the update? that's the whole point, that's the atomicity, that's the vibe check passing. no interlopers, no sneaky second writer, periodt.

the arguments are as follows:

target — the remotely accessible integer data object that's gonna get updated on the remote PE. the type of target should match that implied in the SYNOPSIS section (so like, don't be out here mismatching, bestie 🙈).
pe — an integer that indicates the PE number upon which target is to be updated. if you're using Fortran, it must be a default integer value. fr fr.

📝 NOTES 📝

the term remotely accessible is defined over in intro_shmem(3). go read her, she explains everything. iykyk.

🎀 RETURN VALUES 🎀

she hands you back the contents that had been at the target address on the remote PE prior to the increment. so you get the old number, and the remote object gets the new one. teamwork, babes. 🫶