This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee  document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any  typographical  or formatting errors that appear in this page are most likely to have been introduced
       during  the  conversion  of  the  source  files  to  man  page  format.  To  report  such   errors,   see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                          PTHREAD_COND_DESTROY(3POSIX)

       The  pthread_cond_destroy()  function  shall  destroy 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 reinitialized
       using  pthread_cond_init();  the  results of otherwise referencing the object after it has been destroyed
       are undefined.

       It shall be 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.

       The pthread_cond_init() function  shall  initialize  the  condition  variable  referenced  by  cond  with
       attributes referenced by attr.  If attr is NULL, the default condition variable attributes shall be used;
       the  effect  is  the  same as passing the address of a default condition variable attributes object. Upon
       successful initialization, the state of the condition variable shall become initialized.

       See Section2.9.9, SynchronizationObjectCopiesandAlternativeMappings for further requirements.

       Attempting to initialize an already initialized condition variable 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. The effect shall be equivalent to dynamic initialization
       by a call to pthread_cond_init() with parameter attr specified as NULL, except that no error  checks  are
       performed.

       The  behavior is undefined if the value specified by the cond argument to pthread_cond_destroy() does not
       refer to an initialized condition variable.

       The behavior is undefined if the value specified by the attr argument  to  pthread_cond_init()  does  not
       refer to an initialized condition variable attributes object.

       The pthread_cond_init() function shall 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.

       These functions shall not return an error code of [EINTR].

       Thefollowingsectionsareinformative.

       A condition variable can be destroyed immediately after all the  threads  that  are  blocked  on  it  are
       awakened. For example, consider the following code:

           struct list {
               pthread_mutex_t lm;
               ...
           }

           struct elt {
               key k;
               int busy;
               pthread_cond_t notbusy;
               ...
           }

           /* Find a list element and reserve it. */
           struct elt *
           list_find(struct list *lp, key k)
           {
               struct elt *ep;

               pthread_mutex_lock(&lp->lm);
               while ((ep = find_elt(l, k) != NULL) && ep->busy)
                   pthread_cond_wait(&ep->notbusy, &lp->lm);
               if (ep != NULL)
                   ep->busy = 1;
               pthread_mutex_unlock(&lp->lm);
               return(ep);
           }

           delete_elt(struct list *lp, struct elt *ep)
           {
               pthread_mutex_lock(&lp->lm);
               assert(ep->busy);
               ... remove ep from list ...
               ep->busy = 0;  /* Paranoid. */
           (A) pthread_cond_broadcast(&ep->notbusy);
               pthread_mutex_unlock(&lp->lm);
           (B) pthread_cond_destroy(&ep->notbusy);
               free(ep);
           }

       In  this example, the condition variable and its list element may be freed (line B) immediately after all
       threads waiting for it are awakened (line A), since the mutex and the code ensure that  no  other  thread
       can touch the element to be deleted.

       None.

       pthread_cond_destroy, pthread_cond_init — destroy and initialize condition variables

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

       If an implementation detects that the value specified by the cond argument to pthread_cond_destroy() does
       not  refer  to  an  initialized  condition  variable, it is recommended that the function should fail and
       report an [EINVAL] error.

       If an implementation detects that the value specified by the cond argument to  pthread_cond_destroy()  or
       pthread_cond_init()  refers to a condition variable that is in use (for example, in a pthread_cond_wait()
       call) by another thread, or detects that the value specified by the cond argument to  pthread_cond_init()
       refers  to an already initialized condition variable, it is recommended that the function should fail and
       report an [EBUSY] error.

       If an implementation detects that the value specified by the attr argument  to  pthread_cond_init()  does
       not  refer  to  an  initialized condition variable attributes object, it is recommended that the function
       should fail and report an [EINVAL] error.

       See also pthread_mutex_destroy().

       If successful, the pthread_cond_destroy() and pthread_cond_init() functions shall return zero; otherwise,
       an error number shall be returned to indicate the error.

pthread_cond_broadcast(), pthread_cond_timedwait(), pthread_mutex_destroy()

       The Base Definitions volume of POSIX.1‐2017, <pthread.h>

       #include <pthread.h>

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