/* 
 * tclWinSock.c --
 *
 *	This file contains Windows-specific socket related code.
 *
 * Copyright (c) 1995-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclWinSock.c,v 1.9 1999/04/22 20:28:02 redman Exp $
 * RCS: @(#) $Id: tclWinSock.c,v 1.10 1999/05/26 20:24:43 redman Exp $
 */

#include "tclWinInt.h"

/*
 * The following variable is used to tell whether this module has been
 * initialized.

/*
 * The following defines declare the messages used on socket windows.
 */

#define SOCKET_MESSAGE	WM_USER+1

/*
 * The following defines the timeout value for the WSAWaitForMultipleEvents
 * in milliseconds.
 */

#define TCL_SOCKET_EVENT_TIMEOUT 100

/*
 * The following structure is used to store the data associated with
 * each socket.
 */

typedef struct SocketInfo {
    Tcl_Channel channel;	   /* Channel associated with this socket. */

}

/*
 *----------------------------------------------------------------------
 *
 * SocketThread --
 *
 *      Use a separate thread to check state for the sockets in each
 *      thread.  Using a window isn't the best way, especially if the
 *      WinSock2 API is available and working.  Also, creating N threads
 *      per socket like the pipe, console, and serial drivers isn't
 *      very efficient.  Currently, all sockets are tied to one event.
 *      The overhead involved in creating an event for each socket is
 *      a concern.  But, in order to avoid deadlocks, the call to
 *      WSAWaitForMultipleEvents() needs to timeout to check for
 *      status changes which haven't been handled (race condition).
 *
 * Results:
 *	0 on success.
 *
 * Side effects:
 *
 *----------------------------------------------------------------------
 */

static DWORD WINAPI
SocketThread(LPVOID arg)
{
    SocketInfo *infoPtr;
    WSAEVENT events[2];
    ThreadSpecificData *tsdPtr;
    DWORD result;
    
		
    /*
     * Find the specified socket on the socket list and update its
     * eventState flag.
     */

    events[0] = killEvent;
    events[1] = socketEvent;
    
    while (1) {

	result = (*winSock.WSAWaitForMultipleEvents)(2, events, FALSE,
		WSA_INFINITE, FALSE);
		TCL_SOCKET_EVENT_TIMEOUT, FALSE);

	switch (result) {
	    case WSA_WAIT_TIMEOUT:
	    case (WSA_WAIT_EVENT_0 +1):

		/*
		 * A socket event has fired, determine which socket(s) it was
		 * and which thread(s) it came from.
		 */

		EnterCriticalSection(&socketCS);
		for (tsdPtr = firstWaitingThread; tsdPtr != NULL;
		     tsdPtr = tsdPtr->next) {
		    
		    for (infoPtr = tsdPtr->socketList; infoPtr != NULL; 
			 infoPtr = infoPtr->nextPtr) {
			
			if (GetSocketState(infoPtr) & infoPtr->watchEvents) {
			    Tcl_ThreadAlert(tsdPtr->threadId);
			    SetEvent(tsdPtr->wakeEvent);

			    /*
			     * Only process one at a time for a given thread,
			     * so break here.
			     */
			    
			    break;
			}
		    }
		}
		LeaveCriticalSection(&socketCS);
		(*winSock.WSAResetEvent)(socketEvent);
		break;