THR_WAKE(2)

💖 THR_WAKE 💖

okay bestie, welcome to the thr_wake page from the System Calls Manual (section 2, the system-call girly section, iykyk) 🌸

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✨ NAME ✨

thr_wake — wake up the suspended thread 😴➡️👑

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📚 LIBRARY 📚

Standard C Library (libc, -lc) 🫶

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🌟 SYNOPSIS 🌟

#include <sys/thr.h>

int
thr_wake(long id);

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🦋 DESCRIPTION 🦋

okay so real talk: this function is intended for implementing threading. like, it's a backstage-pass situation, not a main-character situation for your average app. normal applications should be using pthread_cond_timedwait(3) together with pthread_cond_broadcast(3) for typical safe suspension with cooperation of the thread being suspended, or pthread_suspend_np(3) and pthread_resume_np(3) in some specific situations, instead. periodt 💅

now the actual tea ☕ — passing the thread identifier of the calling thread (see thr_self(2)) to thr_wake() sets a thread's flag to cause the next signal-interruptible sleep of that thread in the kernel to fail immediately with the EINTR error. the flag is cleared by an interruptible sleep attempt or by a call to thr_suspend(2). this is used by the system threading library to implement cancellation. iconic, honestly 🎀

if id is not equal to the current thread identifier, the specified thread is woken up if suspended by the thr_suspend system call. and if the thread is not suspended at the time of the thr_wake call? the wake is remembered and the next attempt of the thread to suspend itself with thr_suspend(2) results in immediate return with success. only one wake is remembered — no hoarding, bestie, it's a one-wake-at-a-time situation 🙈

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🔥 RETURN VALUES 🔥

the thr_wake() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error. classic 🫠

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💀 ERRORS 💀

the thr_wake() operation returns these errors:

• [ESRCH] — the specified thread was not found or does not belong to the process of the calling thread. like, she's not here, or she's not yours 💔

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👑 SEE ALSO 👑

ps(1), thr_self(2), thr_suspend(2), pthread_cancel(3), pthread_resume_np(3), pthread_suspend_np(3)

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🌈 STANDARDS 🌈

the thr_suspend() system call is non-standard and is used by 1:1 Threading Library (libthr, -lthr) to implement IEEE Std 1003.1-2001 (“POSIX.1”) pthread(3) functionality. so like, it's giving "not officially in the club but doing the club's whole job" energy ⭐

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Debian 🎀 September 23, 2016 — that's the source and the date, bestie, and this page is officially a wrap 🦋✨💖