PTHREAD_COND_INIT(3) BSD Library Functions Manual PTHREAD_COND_INIT(3)NAME
pthread_cond_init -- create a condition variable
SYNOPSIS
#include <pthread.h>
int
pthread_cond_init(pthread_cond_t *restrict cond, const pthread_condattr_t *restrict attr);
DESCRIPTION
The pthread_cond_init() function creates a new condition variable, with attributes specified with attr. If attr is NULL, the default
attributes are used.
RETURN VALUES
If successful, the pthread_cond_init() function will return zero and put the new condition variable id into cond. Otherwise, an error number
will be returned to indicate the error.
ERRORS
pthread_cond_init() will fail if:
[EAGAIN] The system temporarily lacks the resources to create another condition variable.
[EINVAL] The value specified by attr is invalid.
[ENOMEM] The process cannot allocate enough memory to create another condition variable.
SEE ALSO pthread_cond_broadcast(3), pthread_cond_destroy(3), pthread_cond_signal(3), pthread_cond_timedwait(3), pthread_cond_wait(3)STANDARDS
pthread_cond_init() conforms to ISO/IEC 9945-1:1996 (``POSIX.1'').
BSD July 28, 1998 BSD
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pthread_cond_init(3C)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;
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 condi-
tion 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.
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.
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.
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
|MT-Level |MT-Safe |
+-----------------------------+-----------------------------+
pthread_cond_signal(3C), pthread_cond_broadcast(3C), pthread_cond_wait(3C), pthread_cond_timedwait(3C), pthread_condattr_init(3C),
attributes(5), condition(5), standards(5)
23 Mar 2005 pthread_cond_init(3C)