SHMEM_LOCK(3)

💖 NAME 💖

Hiii bestie, welcome to the Open MPI page for SHMEM_LOCK(3) — it’s giving mutual-exclusion-lock realness. This page covers shmem_set_lock(3), shmem_clear_lock(3), and shmem_test_lock(3): releases, locks, and tests a mutual exclusion memory lock. Periodt. 🎀

✨ SYNOPSIS ✨

C or C++:

#include <mpp/shmem.h>

void shmem_clear_lock(volatile long *lock);

void shmem_set_lock(volatile long *lock);

int shmem_test_lock(volatile long *lock);

Fortran:

INCLUDE "mpp/shmem.fh"

INTEGER lock, SHMEM_TEST_LOCK

CALL SHMEM_CLEAR_LOCK(lock)

CALL SHMEM_SET_LOCK(lock)

I = SHMEM_TEST_LOCK(lock)

🦋 DESCRIPTION 🦋

Okay so shmem_set_lock sets a mutual exclusion lock after waiting for the lock to be freed by any other PE currently holding the lock. Waiting PEs are assured of getting the lock in a first-come, first-served manner. No line-cutting, bestie. 💅

shmem_clear_lock releases a lock previously set by shmem_set_lock after ensuring that all local and remote stores initiated in the critical region are complete. Very “clean up your mess before you dip” energy. ✨

shmem_test_lock sets a mutual exclusion lock only if it is currently cleared. By using this function, a PE can avoid blocking on a set lock. If the lock is currently set, the function returns without waiting. These routines are appropriate for protecting a critical region from simultaneous update by multiple PEs. They accept the following arguments:

• lock — a symmetric data object that is a scalar variable or an array of length 1. This data object must be set to 0 on all processing elements (PEs) prior to the first use. lock must be of type integer. If you are using Fortran, it must be of default kind.

bestie, “set to 0 on all PEs before first use” is not a suggestion, it’s the vibe check. ✅

🌸 NOTES 🌸

The term symmetric data object is defined on intro_shmem(3). Iykyk. 🫶

🔥 RETURN VALUES 🔥

The shmem_test_lock function returns 0 if the lock was originally cleared and this call was able to set the lock. A value of 1 is returned if the lock had been set and the call returned without waiting to set the lock.

👑 SEE ALSO 👑

intro_shmem(3) — go read it, bestie. 💜

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xoxo, your Unix bestie 💅 — this page came from gitclone, source/version status Unreleased developer copy, and the footer has no date listed. SHMEM_LOCK(3) out! 🫶