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(3THR). 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.
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