NAME

pthread_attr_getscope, pthread_attr_setscope — get and set the contentionscope attribute (REALTIME THREADS)

SYNOPSIS

[TPS] #include <pthread.h>

int pthread_attr_getscope(const pthread_attr_t *restrict attr,
       int *restrict contentionscope);
int pthread_attr_setscope(pthread_attr_t *attr, int contentionscope);

DESCRIPTION

The pthread_attr_getscope() and pthread_attr_setscope() functions, respectively, shall get and set the contentionscope attribute in the attr object.

The contentionscope attribute may have the values PTHREAD_SCOPE_SYSTEM, signifying system scheduling contention scope, or PTHREAD_SCOPE_PROCESS, signifying process scheduling contention scope. The symbols PTHREAD_SCOPE_SYSTEM and PTHREAD_SCOPE_PROCESS are defined in the <pthread.h> header.

The behavior is undefined if the value specified by the attr argument to pthread_attr_getscope() or pthread_attr_setscope() does not refer to an initialized thread attributes object.

RETURN VALUE

If successful, the pthread_attr_getscope() and pthread_attr_setscope() functions shall return zero; otherwise, an error number shall be returned to indicate the error.

ERRORS

The pthread_attr_setscope() function shall fail if:

[ENOTSUP]

An attempt was made to set the attribute to an unsupported value.

The pthread_attr_setscope() function may fail if:

[EINVAL]

The value of contentionscope is not valid.

These functions shall not return an error code of [EINTR].

EXAMPLES

None.

APPLICATION USAGE

After these attributes have been set, a thread can be created with the specified attributes using pthread_create(). Using these routines does not affect the current running thread.

See 2.9.4 Thread Scheduling for further details on thread scheduling attributes and their default settings.

RATIONALE

If an implementation detects that the value specified by the attr argument to pthread_attr_getscope() or pthread_attr_setscope() does not refer to an initialized thread attributes object, it is recommended that the function should fail and report an [EINVAL] error.

FUTURE DIRECTIONS

None.

SEE ALSO

pthread_attr_destroy, pthread_attr_getinheritsched, pthread_attr_getschedpolicy, pthread_attr_getschedparam, pthread_create

XBD <pthread.h>, <sched.h>

CHANGE HISTORY

First released in Issue 5. Included for alignment with the POSIX Threads Extension.

Marked as part of the Realtime Threads Feature Group.

Issue 6

The pthread_attr_getscope() and pthread_attr_setscope() functions are marked as part of the Threads and Thread Execution Scheduling options.

The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support the Thread Execution Scheduling option.

The restrict keyword is added to the pthread_attr_getscope() prototype for alignment with the ISO/IEC 9899:1999 standard.

IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/81 is applied, adding a reference to 2.9.4 Thread Scheduling in the APPLICATION USAGE section.

IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/82 is applied, updating the ERRORS section to include optional errors for the case when attr refers to an uninitialized thread attribute object.

Issue 7

The pthread_attr_getscope() and pthread_attr_setscope() functions are marked only as part of the Thread Execution Scheduling option as the Threads option is now part of the Base.

The [EINVAL] error for an uninitialized thread attributes object is removed; this condition results in undefined behavior.

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0453 [314] is applied.

POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0264 [757] is applied.