pthread_cond_init()

Initialize a condition variable

Synopsis:

#include <pthread.h>

pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

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

Arguments:

cond

A pointer to the pthread_cond_t object that you want to initialize.

attr

NULL, or a pointer to a pthread_condattr_t object that specifies the attributes that you want to use for the condvar. For more information, see pthread_condattr_init().

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The pthread_cond_init() function initializes the condition variable cond with the attributes in the condition variable attribute object attr. If attr is NULL, cond is initialized with the default values for the attributes.

---

You should allocate synchronization objects only in normal memory mappings. On certain processors (e.g. some PPC ones), atomic operations such as calls to pthread_mutex_lock() will cause a fault if the control structure is allocated in uncached memory.

---

If the condition variable is statically allocated, you can initialize it with the default attribute values by assigning to it the macro PTHREAD_COND_INITIALIZER.

Condition variables have at least the following attributes defined:

PTHREAD_PROCESS_PRIVATE

The condition variable can only be accessed by threads created within the same process as the thread that initialized the condition variable.

PTHREAD_PROCESS_SHARED

Any thread that has access to the memory where the condition variable is allocated can access the condition variable.

For more information about these attributes, see pthread_condattr_getpshared() and pthread_condattr_setpshared().

Returns:

EOK

Success.

EAGAIN

All kernel synchronization objects are in use.

EBUSY

Previously initialized condition variable, cond, hasn't been destroyed.

EFAULT

A fault occurred when the kernel tried to access cond or attr.

EINVAL

The value specified by cond is invalid.

Classification:

POSIX 1003.1 THR

See also:

pthread_condattr_init(), pthread_cond_destroy()