NAME

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

SYNOPSIS

       #include <pthread.h>

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

       Compile and link with -pthread.

   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
       cancellation  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  cancellation
       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  cancellation 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);

CONFORMING TO

       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)

COLOPHON

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       information   about   reporting   bugs,   and   the  latest  version  of  this  page,  can  be  found  at
       https://www.kernel.org/doc/man-pages/.

Linux                                              2017-09-15                   PTHREAD_CLEANUP_PUSH_DEFER_NP(3)