pthread_condattr_init.3t (2010 09)

p
pthread_condattr_init(3T) pthread_condattr_init(3T)
(Pthread Library)
NAME
pthread_condattr_init(), pthread_condattr_destroy() - initialize or destroy a condition variable attributes
object.
SYNOPSIS
#include <pthread.h>
int pthread_condattr_init(
pthread_condattr_t *attr
);
int pthread_condattr_destroy(
pthread_condattr_t *attr
);
PARAMETERS
attr Pointer to the condition variable attributes object to be initialized or destroyed.
DESCRIPTION
pthread_condattr_init()
initializes the condition variable attributes object attr with the default
values for all attributes. The attributes object describes a condition variable in detail and is passed to the
condition variable initialization function.
When a condition variable attributes object is used to initialize a condition variable, the values of the
individual attributes determine the characteristics of the new condition variable. Attributes objects act
like additional parameters to object initialization. A single attributes object can be used in multiple calls
to the function
pthread_cond_init()
.
When a condition variable is initialized with an attributes object, the attributes are, in effect, copied into
the condition variable. Consequently, any change to the attributes object will not affect any previously
initialized condition variables. Once all condition variables needing a specific attributes object have been
initialized, the attributes object is no longer needed.
The condition variable attributes and their default values are:
process-shared
The default value is PTHREAD_PROCESS_PRIVATE
.
If an initialized condition variable attributes object is reinitialized, undefined behavior results.
pthread_condattr_destroy()
destroys the condition variable attributes object attr . The destroyed
condition variable attributes object ceases to exist and its resources are reclaimed. Using attr after it has
been destroyed results in undefined behavior. A destroyed condition variable attributes object can be
reinitialized using the function
pthread_condattr_init().
Condition variables that have been already initialized using this attributes object are not affected by the
destruction of the condition variable attributes object.
RETURN VALUE
Upon successful completion,
pthread_condattr_init() and pthread_condattr_destroy()
return zero. Otherwise, an error number is returned to indicate the error (the errno variable is not set).
ERRORS
If any of the following occur, the
pthread_condattr_init() function returns the corresponding
error number:
[ENOMEM] There is insufficient memory available in which to initialize the condition variable
attributes object.
[EINVAL] attr is not a valid condition variable attributes object.
For each of the following conditions, if the condition is detected, the
pthread_condattr_destroy()
function returns the corresponding error number:
[EINVAL] attr is not a valid condition variable attributes object.
AUTHOR
pthread_condattr_init() and pthread_condattr_destroy() were derived from the IEEE
POSIX P1003.1c standard.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1