pthread_cleanup_push_defer_np(3)                      Library Functions Manual

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
       GNU; hence the suffix "_np" (nonportable) in the names.

HISTORY
       glibc 2.0

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

Linux man-pages 6.7               2023-10-31  pthread_cleanup_push_defer_np(3)