door_server_create(3DOOR)				      Door Library Functions					 door_server_create(3DOOR)

NAME

       door_server_create - specify an alternative door server thread creation function

SYNOPSIS

       cc -mt [ flag ... ] file ... -ldoor  [ library ... ]
       #include <door.h>

       void (*) () door_server_create(void (*create_proc)(door_info_t*));

DESCRIPTION

       Normally, the doors library creates new door  server threads in response to incoming concurrent door invocations automatically. There is no
       pre-defined upper limit on the number of  server threads that the system creates in response to incoming  invocations (1 server thread  for
       each  active door invocation). These threads are created with the default thread stack size and	POSIX (see standards(5)) threads cancella-
       tion disabled.  The created threads also have the   THR_BOUND |	THR_DETACHED attributes  for Solaris threads and the  PTHREAD_SCOPE_SYSTEM
       |   PTHREAD_CREATE_DETACHED  attributes	for  POSIX  threads. The signal disposition, and scheduling class of the  newly created thread are
       inherited from the  calling thread (initially from the thread calling door_create(), and subsequently from the current active  door  server
       thread).

       The door_server_create() function allows control over the creation of server threads needed for door invocations. The procedure create_proc
       is called every time the available server thread pool is depleted. In the case of private server pools associated with  a  door	 (see  the
       DOOR_PRIVATE  attribute	in   door_create()),  information  on  which  pool  is depleted is passed  to the create function in the form of a
       door_info_t structure. The di_proc and di_data members of the door_info_t structure can be  used as a door identifier associated  with  the
       depleted pool. The create_proc procedure may limit the number of  server threads created and may also create server  threads with appropri-
       ate attributes
	(stack size, thread-specific data, POSIX thread cancellation, signal mask, scheduling attributes, and so forth)  for use with door invoca-
       tions.

       The  specified  server  creation  function  should create user level threads using thr_create() with the  THR_BOUND flag, or in the case of
       POSIX threads, pthread_create() with the  PTHREAD_SCOPE_SYSTEM attribute. The server threads make themselves available  for  incoming  door
       invocations  on	this  process  by  issuing  a  door_return(NULL,  0, NULL, 0). In this case, the  door_return() arguments are ignored. See
       door_return(3DOOR) and thr_create(3C).

       The server threads created by default are enabled for  POSIX thread cancellations which may lead to unexpected  thread  terminations  while
       holding	resources   (such as locks) if the client aborts the associated door_call(). See door_call(3DOOR). Unless the server code is truly
       interested in notifications  of client aborts during a door invocation and  is prepared to handle such  notifications  using   cancellation
       handlers, POSIX thread cancellation should  be disabled for server threads using pthread_setcancelstate (PTHREAD_CANCEL_DISABLE, NULL).

       The  create_proc  procedure  need  not  create any additional server threads if there is at least one server thread currently active in the
       process (perhaps handling another door invocation)  or it may create as many as seen fit each time it is called. If there are no  available
       server  threads	during	an incoming door invocation, the associated  door_call() blocks until a server thread becomes  available. The cre-
       ate_proc procedure must be MT-Safe.

RETURN VALUES

       Upon successful completion, door_server_create() returns a pointer to the previous server creation function. This function has  no  failure
       mode (it cannot fail).

EXAMPLES

       Example 1: Creating door server threads.

       The following example creates door server threads with  cancellation disabled and an 8k stack instead of the default stack size:

       #include <door.h>
       #include <pthread.h>
       #include <thread.h>

       void *
       my_thread(void *arg)
       {
	       pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
	       door_return(NULL, 0, NULL, 0);
       }
       void
       my_create(door_info_t *dip)
       {
	       thr_create(NULL, 8192, my_thread, NULL,
			  THR_BOUND | THR_DETACHED, NULL);
       }
       main()
       {
	       (void)door_server_create(my_create);
	       ...
       }

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Architecture		     |all			   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Evolving			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       door_bind(3DOOR),  door_call(3DOOR), door_create(3DOOR), door_return(3DOOR), libdoor(3LIB), pthread_create(3C), pthread_setcancelstate(3C),
       thr_create(3C), attributes(5), cancellation(5), standards(5)

SunOS 5.10							    20 Aug 1997 					 door_server_create(3DOOR)