PTHREAD...N_UNLOCK(3POSIX)

📦 version 2017a, in debian bookworm, debian trixie, ubuntu jammy, ubuntu noble, ubuntu resolute, ubuntu stonking

💖 PTHREAD_SPIN_UNLOCK — POSIX Programmer's Manual (3POSIX) 💖

okay bestie, we're in the POSIX Programmer's Manual section 3POSIX and this one is literally all about letting go of a spin lock. iconic behavior tbh. 🦋

✨ PROLOG ✨

so like, heads up before we even start: this manual page is part of the POSIX Programmer's Manual. the Linux implementation of this interface may differ (so go check the corresponding Linux manual page for the deets on Linux behavior), or — plot twist 😭 — the interface might not even be implemented on Linux at all. vibe check accordingly.

🎀 NAME 🎀

pthread_spin_unlock — unlock a spin lock object

🌸 SYNOPSIS 🌸

#include <pthread.h>

int pthread_spin_unlock(pthread_spinlock_t *lock);

💅 DESCRIPTION 💅

so the pthread_spin_unlock() function shall release the spin lock referenced by lock — the one that was locked via the pthread_spin_lock() or pthread_spin_trylock() functions. like, you locked it, now you're unlocking it. closure. 🫶

⚠️ the results are undefined if the lock is not held by the calling thread. so don't unlock somebody else's lock, that's not your business fr fr. 💀

if there are threads spinning on the lock when pthread_spin_unlock() is called, the lock becomes available and an unspecified spinning thread shall acquire the lock. (yes, unspecified — the universe picks, not you, and that's fine. 🌈)

⚠️ and the results are undefined if this function is called with an uninitialized thread spin lock. don't do that. please. 🙈

⭐ RETURN VALUE ⭐

upon successful completion, the pthread_spin_unlock() function shall return zero. otherwise, an error number shall be returned to indicate the error. that's it, that's the whole thing. 0 = slay, anything else = look it up. ✨

🔥 ERRORS 🔥

this function shall not return an error code of [EINTR]. periodt.

the following sections are informative. (aka: cute bonus content, not the law. 👑)

🌈 EXAMPLES 🌈

None.

like literally none. the standard said "figure it out bestie". 💅

🦋 APPLICATION USAGE 🦋

None.

same energy. nothing here. moving on. 🎀

💜 RATIONALE 💜

okay so the reasoning behind it, if you're curious:

  • 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. so like, "not a real lock" energy → [EINVAL].
  • 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. so like, "you're not the lock holder" energy → [EPERM].

both of these are recommendations, not requirements, so don't come for me if your implementation is built different. 💖

🧚 FUTURE DIRECTIONS 🧚

None.

the future is empty. no cap. 🍓

👑 SEE ALSO 👑

  • pthread_spin_destroy()
  • pthread_spin_lock()
  • the Base Definitions volume of POSIX.1‐2017, Section 4.12, Memory Synchronization, and <pthread.h>

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 .

and that's the whole page bestie, we ate and left zero crumbs 💅✨

this was brought to you by the IEEE / The Open Group, dated 2017, living in page PTHREAD...N_UNLOCK(3POSIX) — take care of her, she's iconic 🎀🦋💖

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