epics-base/src/ca/bsd_depen.c

/*
 *     	$Id$ 
 *      Author: Jeffrey O. Hill
 *              hill@luke.lanl.gov
 *              (505) 665 1831
 *      Date:  9-93
 *
 *      Experimental Physics and Industrial Control System (EPICS)
 *
 *      Copyright 1991, the Regents of the University of California,
 *      and the University of Chicago Board of Governors.
 *
 *      This software was produced under  U.S. Government contracts:
 *      (W-7405-ENG-36) at the Los Alamos National Laboratory,
 *      and (W-31-109-ENG-38) at Argonne National Laboratory.
 *
 *      Initial development by:
 *              The Controls and Automation Group (AT-8)
 *              Ground Test Accelerator
 *              Accelerator Technology Division
 *              Los Alamos National Laboratory
 *
 *      Co-developed with
 *              The Controls and Computing Group
 *              Accelerator Systems Division
 *              Advanced Photon Source
 *              Argonne National Laboratory
 *
 *      Modification Log:
 *      -----------------
 *
 */

#include "iocinf.h"


/*
 * cac_select_io()
 *
 * NOTE: on multithreaded systems this assumes that the
 * local implementation of select is reentrant
 */
int cac_select_io(struct timeval *ptimeout, int flags)
{
	/*
	 * Use auto timeout so there is no chance of
	 * recursive reuse of ptimeout 
	 */
	struct timeval	autoTimeOut = *ptimeout;
        long            status;
        IIU             *piiu;
        unsigned long   freespace;
	SOCKET		maxfd;
	caFDInfo	*pfdi;

        LOCK;
	pfdi = (caFDInfo *) ellGet(&ca_static->fdInfoFreeList);

	if (!pfdi) {
		pfdi = (caFDInfo *) calloc (1, sizeof(*pfdi));
		if (!pfdi) {
                        ca_printf("CAC: no mem for select ctx?\n");
			UNLOCK;
			return -1;
		}
	}
	ellAdd (&ca_static->fdInfoList, &pfdi->node);

	FD_ZERO (&pfdi->readMask);
	FD_ZERO (&pfdi->writeMask);

	maxfd = 0;
	for(    piiu = (IIU *) iiuList.node.next;
		piiu;
		piiu = (IIU *) piiu->node.next) {

		if (piiu->state==iiu_disconnected) {
			continue;
		}

#ifdef WIN32
		/* Under WIN32, FD_SETSIZE is the number of sockets,
		 * not the max. file descriptor value that you may select() !
		 *
		 * Of course it's not allowed to look into fd_count,
		 * but what shall we do?  -kuk-
		 */

		if (pfdi->readMask.fd_count >= FD_SETSIZE)
		{
			ca_printf(
			"%s.%d: no room for fd %d in fd_set (FD_SETSIZE=%d)\n",
			   __FILE__, __LINE__, piiu->sock_chan, FD_SETSIZE);
			continue;
		}

#else
		if (piiu->sock_chan>=FD_SETSIZE)
		{
			ca_printf(
			"%s.%d: file number %d > FD_SETSIZE=%d ignored\n",
			    __FILE__, __LINE__, piiu->sock_chan, FD_SETSIZE);
			continue;
		}
#endif

                /*
                 * Dont bother receiving if we have insufficient
                 * space for the maximum UDP message, or space
		 * for one TCP byte.
                 */
                if (flags&CA_DO_RECVS) {
                        freespace = cacRingBufferWriteSize (&piiu->recv, TRUE);
                        if (freespace>=piiu->minfreespace) {
				maxfd = max (maxfd,piiu->sock_chan);
                                FD_SET (piiu->sock_chan, &pfdi->readMask);
				piiu->recvPending = TRUE;
                        }
			else {
				piiu->recvPending = FALSE;
			}
                }
		else {
			piiu->recvPending = FALSE;
		}

                if (flags&CA_DO_SENDS) {
			if (piiu->state==iiu_connecting) {
				FD_SET (piiu->sock_chan, &pfdi->writeMask);
			}
			else {
				if (cacRingBufferReadSize(&piiu->send, FALSE)>0) {
					maxfd = max (maxfd,piiu->sock_chan);
					FD_SET (piiu->sock_chan, &pfdi->writeMask);
				}
			}
                }
        }
	UNLOCK;

#	if defined(__hpux)
		status = select(
				maxfd+1,
				(int *)&pfdi->readMask,
				(int *)&pfdi->writeMask,
				(int *)NULL,
				&autoTimeOut);
#	else
		status = select(
				maxfd+1,
				&pfdi->readMask,
				&pfdi->writeMask,
				NULL,
				&autoTimeOut);
#	endif

	/*
	 * get a new time stamp if we have been waiting
	 * for any significant length of time
	 */
	if (ptimeout->tv_sec || ptimeout->tv_usec) {
		cac_gettimeval (&ca_static->currentTime);
	}

        if (status<0) {
                if (SOCKERRNO == EINTR) {
                }
                else if (SOCKERRNO == EWOULDBLOCK) {
                        ca_printf("CAC: blocked at select ?\n");
                }                  
		else if (SOCKERRNO == ESRCH) {
		}
                else {
                        ca_printf (
                                "CAC: unexpected select fail: %s\n",
                                strerror(SOCKERRNO));
                }
        }

	LOCK;
        if (status>0) {
                for (	piiu = (IIU *) iiuList.node.next;
                        piiu;
                        piiu = (IIU *) piiu->node.next) {

                        if (piiu->state==iiu_disconnected) {
                                continue;
                        }

                        if (FD_ISSET(piiu->sock_chan,&pfdi->readMask)) {
                                (*piiu->recvBytes)(piiu);
				/*
				 * if we were not waiting and there is a 
				 * message present then start to suspect that
				 * we are getting behind
				 */
				if (ptimeout->tv_sec==0 || ptimeout->tv_usec==0) {
					flow_control_on(piiu);
				}
                        }
			else if (piiu->recvPending) {
				/*
				 * if we are looking for incoming messages
				 * and there are none then we are certain that
				 * we are not getting behind 
				 */
				flow_control_off(piiu);
			}

			if (FD_ISSET(piiu->sock_chan,&pfdi->writeMask)) {
				(*piiu->sendBytes)(piiu);
			}
                }
        }

	ellDelete (&ca_static->fdInfoList, &pfdi->node);
	ellAdd (&ca_static->fdInfoFreeList, &pfdi->node);
	UNLOCK;

        return status;
}