PTHREAD_CONDATTR(3)

✨ PTHREAD_CONDATTR(3) — condition attribute ops 🎀

okay so this is a page from the Library Functions Manual, and bestie, it's literally all about condition attribute objects. six whole functions, all of them living in the same little squad:

• pthread_condattr_init
• pthread_condattr_destroy
• pthread_condattr_getclock
• pthread_condattr_setclock
• pthread_condattr_getpshared
• pthread_condattr_setpshared

they're the "condition attribute operations" girlies. that's the whole NAME section, periodt. 💅

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🌸 LIBRARY

POSIX Threads Library — you link it with libpthread, -lpthread. no cap, that's the vibe.

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🦋 SYNOPSIS

#include <pthread.h>

int
pthread_condattr_init(pthread_condattr_t *attr);

int
pthread_condattr_destroy(pthread_condattr_t *attr);

int
pthread_condattr_getclock(pthread_condattr_t * restrict attr,
    clockid_t * restrict clock_id);

int
pthread_condattr_setclock(pthread_condattr_t *attr, clockid_t clock_id);

int
pthread_condattr_getpshared(pthread_condattr_t * restrict attr,
    int * restrict pshared);

int
pthread_condattr_setpshared(pthread_condattr_t *attr, int pshared);

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💖 DESCRIPTION

so condition attribute objects are literally just little containers you use to specify parameters to pthread_cond_init(). that's their whole job. iconic behavior honestly. 👑

• pthread_condattr_init() — initializes a condition attribute object with the default attributes. fresh start, clean slate, no baggage. ✨
• pthread_condattr_destroy() — destroys a condition attribute object. it's giving closure. 💀

⏰ the clock ones

pthread_condattr_getclock() will put the value of the clock attribute from attr into the memory area pointed to by clock_id.

pthread_condattr_setclock() will set the clock attribute of attr to the value specified in clock_id.

and lowkey why do you care? because the clock attribute affects how abstime gets interpreted in pthread_cond_timedwait(3) — and it may be set to:

• CLOCK_REALTIME — the default 🕐
• CLOCK_TAI
• CLOCK_MONOTONIC

🫶 the process-shared ones

pthread_condattr_getpshared() will put the value of the process-shared attribute from attr into the memory area pointed to by pshared.

pthread_condattr_setpshared() will set the process-shared attribute of attr to the value specified in pshared.

and pshared may have one of these two values, no in between:

• PTHREAD_PROCESS_PRIVATE — the condition variable it is attached to may only be accessed by threads in the same process as the one that created the object. cozy, contained, just the group chat. 🙈
• PTHREAD_PROCESS_SHARED — the condition variable it is attached to may be accessed by threads in processes other than the one that created the object. it's giving public account energy 🌈

also fr fr go read libthr(3) for the details of the implementation of shared condition variables, and their limitations. there are limits, bestie, don't get too excited. ⭐

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🌟 RETURN VALUES

if successful, these functions return 0. otherwise, an error number is returned to indicate the error. that's it, that's the whole deal. 😭

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💀 ERRORS

pthread_condattr_init() will fail if:

• [ENOMEM] — Out of memory. 🍓

pthread_condattr_destroy() will fail if:

• [EINVAL] — Invalid value for attr.

pthread_condattr_setclock() will fail if:

• [EINVAL] — The value specified in clock_id is not one of the allowed values. (you had three options and you picked wrong, unfortunately 🧚)

pthread_condattr_setpshared() will fail if:

• [EINVAL] — The value specified in pshared is not one of the allowed values.

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👀 SEE ALSO

• libthr(3)
• pthread_cond_init(3)
• pthread_cond_timedwait(3)

like, go read them, they're literally related iykyk 🦋

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👑 STANDARDS

the pthread_condattr_init() and pthread_condattr_destroy() functions conform to ISO/IEC 9945-1:1996 (“POSIX.1”). certified, validated, stamped. ⭐

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and that's the page, bestie!! brought to you by Debian, dated October 27, 2023, and yes this is the PTHREAD_CONDATTR(3) manual page. mwah 💋🎀