NAME    [Toc]    [Back]

       tis_setcancelstate - Changes the calling thread's cancelability
 state

SYNOPSIS    [Toc]    [Back]

       #include <tis.h>

       int tis_setcancelstate(
               int state,
               int *oldstate );

LIBRARY    [Toc]    [Back]

       Standard C Library (libc.so, libc.a)

STANDARDS    [Toc]    [Back]

       None

PARAMETERS    [Toc]    [Back]

       State of general cancelability  to  set  for  the  calling
       thread.  Valid  state  values are as follows: PTHREAD_CANCEL_ENABLE
 PTHREAD_CANCEL_DISABLE Receives  the  value  of
       the calling thread's previous cancelability state.

DESCRIPTION    [Toc]    [Back]

       This routine sets the calling thread's cancelability state
       to the value specified in the state argument  and  returns
       the  calling  thread's previous cancelability state in the
       location referenced by the oldstate argument.

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

       When  a thread is created, its default cancelability state
       is PTHREAD_CANCEL_ENABLE.  When  this  routine  is  called
       prior  to  loading threads, the cancelability state propagates
 to the initial thread in the executing program.

   Possible Problems When Disabling Cancelability    [Toc]    [Back]
       The most important use of a  cancellation  request  is  to
       ensure that indefinite wait operations are terminated. For
       example, a thread  waiting  on  some  network  connection,
       which might take days to respond (or might never respond),
       should be made cancelable.

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

RETURN VALUES    [Toc]    [Back]

       On successful completion, this routine returns the calling
       thread's previous  cancelability  state  in  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: Successful completion.  The
       specified   state   is   not   PTHREAD_CANCEL_ENABLE    or
       PTHREAD_CANCEL_DISABLE.

ERRORS    [Toc]    [Back]

       None

SEE ALSO    [Toc]    [Back]

       Functions: tis_testcancel(3)

       Manuals: Guide to DECthreads and Programmer's Guide



                                            tis_setcancelstate(3)