Tribblix: manual page: pthread_cond

PTHREAD_COND_INIT(3C) Standard C Library Functions PTHREAD_COND_INIT(3C)

NAME

pthread_cond_init, pthread_cond_destroy - initialize or destroy
condition variables

SYNOPSIS

cc -mt [ flag... ] file... -lpthread [ library... ]
#include <pthread.h>

int pthread_cond_init(pthread_cond_t *restrict cond,
const pthread_condattr_t *restrict attr);

int pthread_cond_destroy(pthread_cond_t *cond

pthread_cond_t cond= PTHREAD_COND_INITIALIZER;

DESCRIPTION

The function pthread_cond_init() initializes the condition variable
referenced by cond with attributes referenced by attr. If attr is
NULL, the default condition variable attributes are used; the effect
is the same as passing the address of a default condition variable
attributes object. See pthread_condattr_init(3C). Upon successful
initialization, the state of the condition variable becomes
initialized.

Attempting to initialize an already initialized condition variable
results in undefined behavior.

The function pthread_cond_destroy() destroys the given condition
variable specified by cond; the object becomes, in effect,
uninitialized. An implementation may cause pthread_cond_destroy() to
set the object referenced by cond to an invalid value. A destroyed
condition variable object can be re-initialized using
pthread_cond_init(); the results of otherwise referencing the object
after it has been destroyed are undefined.

It is safe to destroy an initialized condition variable upon which no
threads are currently blocked. Attempting to destroy a condition
variable upon which other threads are currently blocked results in
undefined behavior.

In cases where default condition variable attributes are appropriate,
the macro PTHREAD_COND_INITIALIZER can be used to initialize
condition variables that are statically allocated. The effect is
equivalent to dynamic initialization by a call to pthread_cond_init()
with parameter attr specified as NULL, except that no error checks
are performed.

RETURN VALUES

If successful, the pthread_cond_init() and pthread_cond_destroy()
functions return 0. Otherwise, an error number is returned to
indicate the error. The EBUSY and EINVAL error checks, if
implemented, act as if they were performed immediately at the
beginning of processing for the function and caused an error return
prior to modifying the state of the condition variable specified by
cond.

ERRORS

The pthread_cond_init() function will fail if:

EAGAIN
The system lacked the necessary resources (other than
memory) to initialize another condition variable.

ENOMEM
Insufficient memory exists to initialize the condition
variable.

The pthread_cond_init() function may fail if:

EBUSY
The implementation has detected an attempt to re-initialize
the object referenced by cond, a previously initialized,
but not yet destroyed, condition variable.

EINVAL
The value specified by attr is invalid.

The pthread_cond_destroy() function may fail if:

EBUSY
The implementation has detected an attempt to destroy the
object referenced by cond while it is referenced (for
example, while being used in a pthread_cond_wait() or
pthread_cond_timedwait()) by another thread.

EINVAL
The value specified by cond is invalid.