/*
 * tclUnixNotify.c --
 *
 *	This file contains the implementation of the select-based
 *	Unix-specific notifier, which is the lowest-level part of the
 *	Tcl event loop.  This file works together with
 *	../generic/tclNotify.c.
 *
 * 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: tclUnixNotfy.c,v 1.1.2.4 1998/12/01 05:01:03 stanton Exp $
 */

#include "tclInt.h"
#include "tclPort.h"
#include <signal.h> 

/*

    struct ThreadSpecificData *nextPtr, *prevPtr;
                                /* All threads that are currently waiting on 
                                 * an event have their ThreadSpecificData
                                 * structure on a doubly-linked listed formed
                                 * from these pointers.  You must hold the
                                 * notifierMutex lock before accessing these
                                 * fields. */
    Tcl_Condition waitCV;     /* Any other thread alerts a notifier
				 * that an event is ready to be processed
				 * by signaling this condition variable. */
    int eventReady;           /* True if an event is ready to be processed.
                               * Used as condition flag together with
                               * waitCV above. */
#endif
} ThreadSpecificData;

static Tcl_ThreadDataKey dataKey;

#ifdef TCL_THREADS
/*

ClientData
Tcl_InitNotifier()
{
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

#ifdef TCL_THREADS
    tsdPtr->eventReady = 0;

    /*
     * Start the Notifier thread if necessary.
     */

    Tcl_MutexLock(&notifierMutex);
    if (notifierCount == 0) {
	if (TclpThreadCreate(&notifierThread, NotifierThreadProc, NULL) != TCL_OK) {

void
Tcl_AlertNotifier(clientData)
    ClientData clientData;
{
#ifdef TCL_THREADS
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) clientData;
    Tcl_MutexLock(&notifierMutex);
    tsdPtr->eventReady = 1;
    TclpConditionNotify(&tsdPtr->waitCV);
    Tcl_MutexUnlock(&notifierMutex);
#endif
}

/*
 *----------------------------------------------------------------------

    ClientData clientData;	/* Arbitrary data to pass to proc. */
{
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
    FileHandler *filePtr;
    int index, bit;

    for (filePtr = tsdPtr->firstFileHandlerPtr; filePtr != NULL;
	 filePtr = filePtr->nextPtr) {
	if (filePtr->fd == fd) {
	    break;
	}
    }
    if (filePtr == NULL) {
	filePtr = (FileHandler*) ckalloc(sizeof(FileHandler));
	filePtr->fd = fd;

    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    /*
     * Find the entry for the given file (and return if there isn't one).
     */

    for (prevPtr = NULL, filePtr = tsdPtr->firstFileHandlerPtr; ;
	 prevPtr = filePtr, filePtr = filePtr->nextPtr) {
	if (filePtr == NULL) {
	    return;
	}
	if (filePtr->fd == fd) {
	    break;
	}
    }

     * the event.  We do this rather than keeping a pointer to the file
     * handler directly in the event, so that the handler can be deleted
     * while the event is queued without leaving a dangling pointer.
     */

    tsdPtr = TCL_TSD_INIT(&dataKey);
    for (filePtr = tsdPtr->firstFileHandlerPtr; filePtr != NULL;
	 filePtr = filePtr->nextPtr) {
	if (filePtr->fd != fileEvPtr->fd) {
	    continue;
	}

	/*
	 * The code is tricky for two reasons:
	 * 1. The file handler's desired events could have changed

        waitingListPtr = tsdPtr;
	tsdPtr->onList = 1;
	write(triggerPipe, "", 1);
    }

    memset((VOID *) tsdPtr->readyMasks, 0, 3*MASK_SIZE*sizeof(fd_mask));

    if (!tsdPtr->eventReady) {
        TclpConditionWait(&tsdPtr->waitCV, &notifierMutex, timePtr);
    }
    tsdPtr->eventReady = 0;

    if (waitForFiles && tsdPtr->onList) {
	/*
	 * Remove the ThreadSpecificData structure of this thread from the
	 * waiting list.  Alert the notifier thread to recompute its select
	 * masks - skipping this caused a hang when trying to close a pipe
	 * which the notifier thread was still doing a select on.
	 */

        if (tsdPtr->prevPtr) {
            tsdPtr->prevPtr->nextPtr = tsdPtr->nextPtr;
        } else {
            waitingListPtr = tsdPtr->nextPtr;
        }
        if (tsdPtr->nextPtr) {
            tsdPtr->nextPtr->prevPtr = tsdPtr->prevPtr;
        }
        tsdPtr->nextPtr = tsdPtr->prevPtr = NULL;
	tsdPtr->onList = 0;
	write(triggerPipe, "", 1);
    }

    
#else
    memcpy((VOID *) tsdPtr->readyMasks, (VOID *) tsdPtr->checkMasks,
	    3*MASK_SIZE*sizeof(fd_mask));
    numFound = select(tsdPtr->numFdBits,

#endif

    /*
     * Queue all detected file events before returning.
     */

    for (filePtr = tsdPtr->firstFileHandlerPtr; (filePtr != NULL);
	 filePtr = filePtr->nextPtr) {
	index = filePtr->fd / (NBBY*sizeof(fd_mask));
	bit = 1 << (filePtr->fd % (NBBY*sizeof(fd_mask)));
	mask = 0;

	if (tsdPtr->readyMasks[index] & bit) {
	    mask |= TCL_READABLE;
	}

            for (i = 0; i < maskSize; i++) {
                word = maskPtr[i] & ((long*)tsdPtr->checkMasks)[i];
                found |= word;
                (((long*)(tsdPtr->readyMasks))[i]) = word;
	    }
            if (found || (tsdPtr->pollState & POLL_DONE)) {
                tsdPtr->eventReady = 1;
		TclpConditionNotify(&tsdPtr->waitCV);
		if (tsdPtr->onList) {
		    /*
		     * Remove the ThreadSpecificData structure of this thread
		     * from the waiting list. This prevents us from continuously
		     * spining on select until the other threads runs and
		     * services the file event.