PTHREAD_SPIN_UNLOCK(3P)

💖 PTHREAD_SPIN_UNLOCK(3P) 💖

okay bestie, so this is a page from the POSIX Programmer's Manual (yes, the POSIX Programmer's Manual, we're being fancy today) 🎀

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🌸 PROLOG 🌸

This manual page is part of the POSIX Programmer's Manual. Heads up though: the Linux implementation of this interface may differ (so go consult the corresponding Linux manual page for the deets on Linux behavior), or the interface may just... not be implemented on Linux at all. 🙈

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✨ NAME ✨

pthread_spin_unlock — unlock a spin lock object 🔓

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🦋 SYNOPSIS 🦋

#include <pthread.h>

int pthread_spin_unlock(pthread_spinlock_t *lock);

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💅 DESCRIPTION 💅

So the pthread_spin_unlock() function shall release the spin lock referenced by lock — and that lock has to be one that was locked via the pthread_spin_lock() or pthread_spin_trylock() functions. That's the whole vibe. 🫶

⚠️ The results are undefined if the lock is not held by the calling thread. like... not your lock, not your problem, but also undefined behavior. 💀

If there are threads spinning on the lock when pthread_spin_unlock() gets called, the lock becomes available and an unspecified spinning thread shall acquire the lock. Not which thread — unspecified, bestie. The universe decides. 🌈

⚠️ Also! The results are undefined if this function is called with an uninitialized thread spin lock. Please initialize your locks, i'm begging. 😭

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⭐ RETURN VALUE ⭐

Upon successful completion, the pthread_spin_unlock() function shall return zero — iconic, flawless, no notes. 💖

Otherwise, an error number shall be returned to indicate the error. So like, non-zero = something went sideways.

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🍓 ERRORS 🍓

This function shall not return an error code of [EINTR]. Not a thing here, don't @ me.

The following sections are informative. 👑

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🧚 EXAMPLES 🧚

None. 💀 (the audacity, honestly — no examples, we're on our own)

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🎀 APPLICATION USAGE 🎀

None. 🙈 (also nothing here, go forth and lock responsibly)

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👑 RATIONALE 👑

If an implementation detects that the value specified by the lock argument to pthread_spin_unlock() does not refer to an initialized spin lock object, it is recommended that the function should fail and report an [EINVAL] error. 📋

If an implementation detects that the value specified by the lock argument to pthread_spin_unlock() refers to a spin lock object for which the current thread does not hold the lock, it is recommended that the function should fail and report an [EPERM] error. 🚫

(Key word: recommended. It's giving "we suggest", not "we require". iykyk.)

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🌈 FUTURE DIRECTIONS 🌈

None. The future is, apparently, exactly like the present. 🦋

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🔥 SEE ALSO 🔥

• pthread_spin_destroy()
• pthread_spin_lock()

The Base Definitions volume of POSIX.1‐2017, Section 4.12, Memory Synchronization, <pthread.h> 📚

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💜 COPYRIGHT 💜

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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and that's the whole page, bestie — brought to you by IEEE/The Open Group, dated 2017, page PTHREAD_SPIN_UNLOCK(3P) ✨ stay locked, stay unlocked, just don't do it in the wrong order 💅🫶💖