VMS Help POSIX Threads, PTHREAD routines, pthread_setcancelstate  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Sets the calling thread's cancelability state.

1 - C Binding

    #include <pthread.h>

    int
    pthread_setcancelstate (
             int   state,
             int   *oldstate );

2 - Arguments

 state

    State of general cancelability to set for the calling thread. The
    following are valid cancel state values:

       PTHREAD_CANCEL_ENABLE
       PTHREAD_CANCEL_DISABLE

 oldstate

    Previous cancelability state for the calling thread.

3 - Description

    This routine sets the calling thread's cancelability state and
    returns the calling thread's previous cancelability state in
    oldstate.

    When cancelability state is set to PTHREAD_CANCEL_DISABLE, a
    cancelation request cannot be delivered to the thread, even if a
    cancelable routine is called or asynchronous cancelability type
    is enabled.

    When a thread is created, its default cancelability state is
    PTHREAD_CANCEL_ENABLE.

    Possible Problems When Disabling Cancelability

    The most important use of thread cancelation is to ensure
    that indefinite wait operations are terminated. For example, a
    thread that waits on some network connection, which can possibly
    take days to respond (or might never respond), should be made
    cancelable.

    When a thread's cancelability is disabled, no routine in that
    thread is cancelable. As a result, the user is unable to
    cancel the operation performed by that thread. When disabling
    cancelability, be sure that no long waits can occur or that it is
    necessary for other reasons to defer cancelation requests around
    that particular region of code.

4 - Return Values

    On successful completion, this routine returns the calling
    thread's previous cancelability state in the location specified
    by the oldstate argument.

    If an error condition occurs, this routine returns an integer
    value indicating the type of error. Possible return values are as
    follows:

    Return      Description

    0           Successful completion.
    [EINVAL]    The specified state is not PTHREAD_CANCEL_ENABLE or
                PTHREAD_CANCEL_DISABLE.

5 - Associated Routines

       pthread_cancel()
       pthread_setcanceltype()
       pthread_testcancel()