pthread_condattr_getpshared(3pthread)

pthread_condattr_getpshared, pthread_condattr_setpshared -- get and set the process-shared condition variable attributes

Synopsis

cc [options] -Kthread file

#include <pthread.h>

int pthread_condattr_getpshared(const pthread_condattr_t *attr,
    int *pshared);
int pthread_condattr_setpshared(pthread_condattr_t *attr,
    int pshared);

Description

pthread_condattr_getpshared obtains the value of the process-shared attribute from the attributes object referenced by attr. The pthread_condattr_setpshared function is used to set the process-shared attribute in an initialized attributes object referenced by attr.

The process-shared attribute is set to PTHREAD_PROCESS_SHARED to permit a condition variable to be operated upon by any thread that has access to the memory where the condition variable is allocated, even if the condition variable is allocated in memory that is shared by multiple processes. If the process-shared attribute is PTHREAD_PROCESS_PRIVATE, the condition variable will only be operated upon by threads created within the same process as the thread that initialised the condition variable; if threads of differing processes attempt to operate on such a condition variable, the behaviour is undefined. The default value of the attribute is PTHREAD_PROCESS_PRIVATE.

Return values

If successful, the pthread_condattr_setpshared function returns zero. Otherwise, an error number is returned to indicate the error.

If successful, the pthread_condattr_getpshared function returns zero and stores the value of the process-shared attribute of attr into the object referenced by the pshared parameter. Otherwise, an error number is returned to indicate the error.

Diagnostics

If the following condition is detected, pthread_condattr_getpshared and pthread_condattr_setpshared return the corresponding value:

EINVAL: The value specified by attr is invalid.

If the following condition is detected, pthread_condattr_setpshared returns the corresponding value:

EINVAL: The new value specified for the attribute is outside the range of legal values for that attribute.

References

pthread_condattr_init(3pthread), pthread_create(3pthread), pthread_mutex_init(3pthread), pthread_cond_init(3pthread), pthread(4)

Standards compliance

The Single UNIX Specification, Version 2; The Open Group.