pthread_cond_init(3T)          DG/UX R4.11MU05         pthread_cond_init(3T)


NAME
       pthreadcondinit, pthreadconddestroy - initialize or destroy
       condition variables

SYNOPSIS
       #include <pthread.h>

       int pthreadcondinit(pthreadcondt *cond,
                             pthreadcondattrt *attr);

       int pthreadconddestroy(pthreadcondt *cond);

   where:
       cond   A pointer to a condition variable
       attr   A pointer to an condition attributes object, or NULL

DESCRIPTION
       The pthreadcondinit() function initializes the condition variable
       pointed to by cond with attributes specified by attr.  If attr is
       NULL the default condition attributes are used; the effect is the
       same as passing the address of a newly initialized condition
       attributes object.

       If the pthreadcondinit() function fails, the condition variable is
       not initialized and the contents of the condition variable are
       undefined.

       The pthreadconddestroy() function destroys the condition variable
       pointed to by cond.  Destroying a condition variable upon which other
       threads are currently blocked or upon which other threads have yet to
       execute operations results in undefined behavior.

DIAGNOSTICS
   Returns
       If successful, the functions returns 0.  Otherwise they return -1 and
       set errno to indicate the error.

   Errors
       For each of the following conditions, pthreadcondinit() returns -1
       and sets errno to the corresponding value:

       [EAGAIN]  The system lacked the necessary resources to initialize
                 another condition variable.  In DG/UX, this occurs when
                 trying to initialize a process-shared condition variable,
                 and the system-imposed limit on the number of global
                 synchronization queues (for process-shared mutexes and
                 condition variables) has been exceeded.

       [ENOMEM]  Insufficient memory exists to initialize the condition
                 variable.  In DG/UX, this occurs when trying to allocate
                 more global synchronization queues in order to initialize a
                 process-shared condition variable.

       For each of the following conditions, pthreadconddestroy() returns
       -1 and sets errno to the corresponding value:

       [EBUSY]   The system has detected an attempt to destroy a condition
                 variable while it is referenced (for example, while being
                 used in a call to pthreadcondwait() or
                 pthreadcondtimedwait() by another thread).

       [EINVAL]  The value specified by cond is invalid.  This occurs when
                 DG/UX has detected that cond does not point to a properly
                 initialized condition variable.

SEE ALSO
       pthreadcondbroadcast(3T), pthreadcondsignal(3T),
       pthreadcondtimedwait(3T), pthreadcondwait(3T), threads(5).

NOTES
       The terms "condition" and "condition variable" are equivalent.

       The kernel configuration variable MAXGLOBALSQS can be used to change
       the system-imposed limit on the number of global synchronization
       queues used for process-shared mutexes and condition variables.

       If a condition variable is initialized as process-shared, the
       underlying global synchronization queues are not automatically
       cleaned up if the process terminates or the shared memory area
       holding the condition variable is deallocated.  They can only be
       released by calls to pthreadconddestroy() on the condition
       variable.  An application that uses process-shared condition
       variables should ensure that it properly destroys all process-shared
       condition variables in order to avoid a leak of global
       synchronization queues.

       DG/UX does not currently allocate any extra memory in order to
       initialize condition variables that are not process-shared.


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