NAME
pthread_condattr_destroy
pthread_condattr_init —
destroy and initialize the condition variable attributes
object
SYNOPSIS
#include
<pthread.h>
int pthread_condattr_destroy(pthread_condattr_t *attr); int pthread_condattr_init(pthread_condattr_t *attr);
DESCRIPTION
The pthread_condattr_destroy () function
shall destroy a condition variable attributes object; the object becomes, in
effect, uninitialized. An implementation may cause
pthread_condattr_destroy () to set the object
referenced by attr to an invalid value. A destroyed
attr attributes object can be reinitialized using
pthread_condattr_init (); the results of otherwise
referencing the object after it has been destroyed are undefined.
The pthread_condattr_init () function shall initialize a condition variable attributes object attr with the default value for all of the attributes defined by the implementation.
Results are undefined if pthread_condattr_init () is called specifying an already initialized attr attributes object.
After a condition variable attributes object has been used to initialize one or more condition variables, any function affecting the attributes object (including destruction) shall not affect any previously initialized condition variables.
This volume of POSIX.1-2017 requires two attributes, the clock attribute and the process-shared attribute.
Additional attributes, their default values, and the names of the associated functions to get and set those attribute values are implementation-defined.
The behavior is undefined if the value specified by the
attr argument to
pthread_condattr_destroy () does not refer to an
initialized condition variable attributes object.
RETURN VALUE
If successful, the
pthread_condattr_destroy () and
pthread_condattr_init () functions shall return zero;
otherwise, an error number shall be returned to indicate the error.
ERRORS
The pthread_condattr_init () function shall fail if:
- [ENOMEM]
- Insufficient memory exists to initialize the condition variable attributes object.
These functions shall not return an error code of [EINTR].
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
A process-shared attribute has been defined for condition variables for the same reason it has been defined for mutexes.
If an implementation detects that the value specified by the
attr argument to
pthread_condattr_destroy () does not refer to an
initialized condition variable attributes object, it is recommended that the
function should fail and report an [EINVAL] error.
See also pthread_attr_destroy(3) and pthread_mutex_destroy(3).
FUTURE DIRECTIONS
None.
SEE ALSO
pthread_attr_destroy(3), pthread_cond_destroy(3), pthread_condattr_getpshared(3), pthread_create(3), pthread_mutex_destroy(3)
XBD <pthread.h>
CHANGE HISTORY
First released in Issue 5. Included for alignment with the POSIX Threads Extension.
Issue 6
The pthread_condattr_destroy () and
pthread_condattr_init () functions are marked as part of
the Threads option.
Issue 7
The pthread_condattr_destroy () and
pthread_condattr_init () functions are moved from the
Threads option to the Base.
The [EINVAL] error for an uninitialized condition variable attributes object is removed; this condition results in undefined behavior.