Manpages - pthread_cleanup_push_defer_np.3

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

  #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

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);

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

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

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