PTHREAD_M...ONSISTENT(3P)

💖 PTHREAD_MUTEX_CONSISTENT(3P) 💖

okay bestie, gather round, because we're reading a page from the POSIX Programmer's Manual and it's genuinely a bop. this one's pthread_mutex_consistent(3P), and yes the header up top says PTHREAD_M...ONSISTENT(3P) because even manpage titles gotta stay mysterious sometimes. it's from IEEE/The Open Group, dated 2017. let's get into it 🫶

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✨ PROLOG ✨

so, real talk: this manual page is part of the POSIX Programmer's Manual.

heads up, bestie — the Linux implementation of this interface may differ (so go consult the corresponding Linux manual page for the deets on Linux behavior), or honestly the interface may not be implemented on Linux at all. vibe check your platform first, fr fr.

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🌸 NAME 🌸

pthread_mutex_consistent — mark state protected by robust mutex as consistent

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🎀 SYNOPSIS 🎀

#include <pthread.h>

int pthread_mutex_consistent(pthread_mutex_t *mutex);

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🦋 DESCRIPTION 🦋

so here's the tea ☕. if mutex is a robust mutex that's sitting in an inconsistent state, the pthread_mutex_consistent() function can be used to mark the state protected by the mutex referenced by mutex as consistent again. slay, we fixed it.

now, the dramatic part 😭: if an owner of a robust mutex terminates while holding the mutex, the mutex becomes inconsistent, and the next thread that acquires the mutex lock shall be notified of that state by the return value [EOWNERDEAD]. in that case, the mutex does not become normally usable again until the state is marked consistent. like, it's in its flop era until you fix it.

and if the thread which acquired the mutex lock with the return value [EOWNERDEAD] terminates before calling either pthread_mutex_consistent() or pthread_mutex_unlock(), then the next thread that acquires the mutex lock shall be notified about the state of the mutex by the return value [EOWNERDEAD]. the drama just keeps going, honestly.

⚠️ undefined behavior alert ⚠️ — the behavior is undefined if the value specified by the mutex argument to pthread_mutex_consistent() does not refer to an initialized mutex. do not do this. it's giving chaos and not the cute kind. 💀

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💅 RETURN VALUE 💅

upon successful completion, the pthread_mutex_consistent() function shall return zero. otherwise, an error value shall be returned to indicate the error. iconic, simple, no notes.

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🔥 ERRORS 🔥

the pthread_mutex_consistent() function shall fail if:

• EINVAL — the mutex object referenced by mutex is not robust or does not protect an inconsistent state.

also, these functions shall not return an error code of [EINTR]. periodt.

the following sections are informative. (translation: they're the commentary track, not the main plot 🎬)

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🌈 EXAMPLES 🌈

None.

yep. nothing. empty. a beautiful blank canvas. 🙈

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🍓 APPLICATION USAGE 🍓

okay so important distinction, bestie: the pthread_mutex_consistent() function is only responsible for notifying the implementation that the state protected by the mutex has been recovered and that normal operations with the mutex can be resumed.

it is the responsibility of the application to recover the state so it can be reused. yes, you, the app, gotta do the actual work. the function is just the messenger 🧚

and if the application is not able to perform the recovery, it can notify the implementation that the situation is unrecoverable by a call to pthread_mutex_unlock() without a prior call to pthread_mutex_consistent(). in which case, subsequent threads that attempt to lock the mutex will fail to acquire the lock and be returned [ENOTRECOVERABLE]. no cap. 😭

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👑 RATIONALE 👑

if an implementation detects that the value specified by the mutex argument to pthread_mutex_consistent() does not refer to an initialized mutex, it is recommended that the function should fail and report an [EINVAL] error. just a lil suggestion from the standards girlies 💜

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⭐ FUTURE DIRECTIONS ⭐

None.

the future is bright and also empty. main character energy with no sequels planned 🌟

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🌸 SEE ALSO 🌸

• pthread_mutex_lock()
• pthread_mutexattr_getrobust()

the Base Definitions volume of POSIX.1‐2017, <pthread.h>

iykyk, go read those next 💖

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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. (referee = the one with the final say, bestie, no arguing 🫶)

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!! 💅 shoutout to IEEE/The Open Group, 2017, for bringing us this PTHREAD_M...ONSISTENT(3P) moment — stay robust, stay consistent, and always initialize your mutexes, bestie. mwah 💖✨