NAME

       pthread_cleanup_push_defer_np,   pthread_cleanup_pop_restore_np  -  push  and  pop  thread
       cancelation clean-up handlers while saving cancelability type

LIBRARY

       POSIX threads library (libpthread, -lpthread)

SYNOPSIS

       #include <pthread.h>

       void pthread_cleanup_push_defer_np(void (*routine)(void *), void *arg);
       void pthread_cleanup_pop_restore_np(int execute);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       pthread_cleanup_push_defer_np(), pthread_cleanup_pop_defer_np():
           _GNU_SOURCE

DESCRIPTION

       These functions are the same as pthread_cleanup_push(3) and pthread_cleanup_pop(3), except
       for the differences noted on this page.

       Like  pthread_cleanup_push(3),  pthread_cleanup_push_defer_np()  pushes  routine  onto the
       thread's stack of cancelation clean-up handlers.  In addition, it also saves the  thread's
       current   cancelability   type,  and  sets  the  cancelability  type  to  "deferred"  (see
       pthread_setcanceltype(3)); this ensures that cancelation clean-up will occur even  if  the
       thread's cancelability type was "asynchronous" before the call.

       Like  pthread_cleanup_pop(3),  pthread_cleanup_pop_restore_np() pops the top-most clean-up
       handler from the thread's  stack  of  cancelation  clean-up  handlers.   In  addition,  it
       restores  the  thread's  cancelability  type  to  its  value  at  the time of the matching
       pthread_cleanup_push_defer_np().

       The caller must ensure that calls to these functions are paired within the same  function,
       and  at  the  same  lexical  nesting  level.   Other  restrictions  apply, as described in
       pthread_cleanup_push(3).

       This sequence of calls:

           pthread_cleanup_push_defer_np(routine, arg);
           pthread_cleanup_pop_restore_np(execute);

       is equivalent to (but shorter and more efficient than):

           int oldtype;

           pthread_cleanup_push(routine, arg);
           pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, &oldtype);
           ...
           pthread_setcanceltype(oldtype, NULL);
           pthread_cleanup_pop(execute);

STANDARDS

       These functions are nonstandard GNU extensions; hence the suffix  "_np"  (nonportable)  in
       the names.

SEE ALSO

       pthread_cancel(3),           pthread_cleanup_push(3),           pthread_setcancelstate(3),
       pthread_testcancel(3), pthreads(7)