SYNOPSIS
        void slow_shut_down(int minutes)

DESCRIPTION
        Schedule a shutdown for the near future. minutes is the
        desired time in minutes till the shutdown:
         six, if just the user reserve has been put into use.
         one, if the (smaller) master reserve has been put into use as
              well.

        The interpreter calls this function when it runs low on
        memory. At this time, it has freed its reserve, but since it
        won't last long, the interpreter needs to be shut down. The
        delay is to give the users the opportunity to finish their
        current tasks, but don't take the 'minutes' for granted, just
        deduce the urgency from it.

        It is possible that the driver may reallocate some memory
        after the function has been called, and then run again into a
        low memory situation, calling this function again.

        This function might load an 'Armageddon' object and tell it
        what to do. It is the Armageddon object then which performs
        the shutdown.

        Technical: The memory handling of the interpreter includes
        three reserved areas: user, system and master. All three are
        there to insure that the system shuts down gracefully when the
        memory runs out: the user area to give the users time to
        quit normally, the others to enable emergency-logouts when the
        user reserve is used up as well.

        The areas are allocated at start of the interpreter, and
        released when no more memory could be obtained from the host.
        In such a case, one of the remaining areas is freed (so the
        operation can continue a short while) and a garbage collection
        is initiated. If the garbage collection recycles enough memory
        (either true garbage or by the aid of the quota_demon) to
        reallocate the areas, all is fine, else the system shut down
        is invoked by a call to this function.

SEE ALSO
        quota_demon(M), notify_shutdown(M), shutdown(E), malloc(D), memory(C)
        low_memory(M)