PTHREAD...DWRLOCK(3POSIX)

💖 PTHREAD_RWLOCK_TIMEDWRLOCK 💖

okay bestie, gather round, we're doing POSIX threads today and honestly? this one's a bop. This page lives in the POSIX Programmer's Manual, section 3POSIX, and it's filed under PTHREAD...DWRLOCK(3POSIX). 🦋

🌸 PROLOG 🌸

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (so like, go read the corresponding Linux manual page for the tea on Linux behavior), or honestly the interface may just not be implemented on Linux at all. 🙈

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✨ NAME ✨

pthread_rwlock_timedwrlock — lock a read-write lock for writing

🎀 SYNOPSIS 🎀

#include <pthread.h>
#include <time.h>

int pthread_rwlock_timedwrlock(pthread_rwlock_t *restrict rwlock,
    const struct timespec *restrict abstime);

💅 DESCRIPTION 💅

So pthread_rwlock_timedwrlock() shall apply a write lock to the read-write lock referenced by rwlock, exactly like the pthread_rwlock_wrlock() function does. But here's the twist: if the lock cannot be acquired without waiting for other threads to unlock it, this wait shall be terminated when the specified timeout expires. ⏰

The timeout shall expire when the absolute time specified by abstime passes — measured by the clock on which timeouts are based (that is, when the value of that clock equals or exceeds abstime) — or if the absolute time specified by abstime has already been passed at the time of the call. no waiting around for a moment that already happened, periodt.

The timeout shall be based on the CLOCK_REALTIME clock. The resolution of the timeout shall be the resolution of the CLOCK_REALTIME clock. The timespec data type is defined in the <time.h> header. Under no circumstances shall the function fail with a timeout if the lock can be acquired immediately. The validity of the abstime parameter need not be checked if the lock can be immediately acquired. 😌

If a signal that causes a signal handler to be executed is delivered to a thread blocked on a read-write lock via a call to pthread_rwlock_timedwrlock(), upon return from the signal handler the thread shall resume waiting for the lock as if it was not interrupted. iconic behavior, we love a resilient queen. ✨

⚠️ The calling thread may deadlock if at the time the call is made it holds the read-write lock. And the results are undefined if this function is called with an uninitialized read-write lock. fr fr, don't do that. 💀

🌈 RETURN VALUE 🌈

pthread_rwlock_timedwrlock() shall return zero if the lock for writing on the read-write lock object referenced by rwlock is acquired. Otherwise, an error number shall be returned to indicate the error. 🫶

🔥 ERRORS 🔥

The pthread_rwlock_timedwrlock() function shall fail if:

• ETIMEDOUT — the lock could not be acquired before the specified timeout expired. clock ran out bestie, sorry.

The pthread_rwlock_timedwrlock() function may fail if:

• EDEADLK — a deadlock condition was detected, or the calling thread already holds the rwlock. 💀
• EINVAL — the abstime nanosecond value is less than zero or greater than or equal to 1000 million. girl, that's not a real nanosecond value.

This function shall not return an error code of [EINTR]. not on the menu, not happening.

The following sections are informative.

🦋 EXAMPLES 🦋

None.

💜 APPLICATION USAGE 💜

Applications using this function may be subject to priority inversion, as discussed in the Base Definitions volume of POSIX.1‐2017, Section 3.291, Priority Inversion.

⭐ RATIONALE ⭐

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

🍓 FUTURE DIRECTIONS 🍓

None.

👑 SEE ALSO 👑

• pthread_rwlock_destroy()
• pthread_rwlock_rdlock()
• pthread_rwlock_timedrdlock()
• pthread_rwlock_trywrlock()
• pthread_rwlock_unlock()

The Base Definitions volume of POSIX.1‐2017, Section 3.291, Priority Inversion, Section 4.12, Memory Synchronization, <pthread.h>, <time.h>

🧚 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, you ate 💅 this one comes to you from IEEE/The Open Group, dated 2017, filed under PTHREAD...DWRLOCK(3POSIX). go forth and lock responsibly 🫶✨