tclnotify.c

linux系统下的音频通信

/* 
 * tclNotify.c --
 *
 *	This file implements the generic portion of the Tcl notifier.
 *	The notifier is lowest-level part of the event system.  It
 *	manages an event queue that holds Tcl_Event structures.  The
 *	platform specific portion of the notifier is defined in the
 *	tcl*Notify.c files in each platform directory.
 *
 * 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.
 *
 * SCCS: @(#) tclNotify.c 1.16 97/09/15 15:12:52
 */

#include "tclInt.h"
#include "tclPort.h"

/*
 * The following static indicates whether this module has been initialized.
 */

static int initialized = 0;

/*
 * For each event source (created with Tcl_CreateEventSource) there
 * is a structure of the following type:
 */

typedef struct EventSource {
    Tcl_EventSetupProc *setupProc;
    Tcl_EventCheckProc *checkProc;
    ClientData clientData;
    struct EventSource *nextPtr;
} EventSource;

/*
 * The following structure keeps track of the state of the notifier.
 * The first three elements keep track of the event queue.  In addition to
 * the first (next to be serviced) and last events in the queue, we keep
 * track of a "marker" event.  This provides a simple priority mechanism
 * whereby events can be inserted at the front of the queue but behind all
 * other high-priority events already in the queue (this is used for things
 * like a sequence of Enter and Leave events generated during a grab in
 * Tk).
 */

static struct {
    Tcl_Event *firstEventPtr;	/* First pending event, or NULL if none. */
    Tcl_Event *lastEventPtr;	/* Last pending event, or NULL if none. */
    Tcl_Event *markerEventPtr;	/* Last high-priority event in queue, or
				 * NULL if none. */
    int serviceMode;		/* One of TCL_SERVICE_NONE or
				 * TCL_SERVICE_ALL. */
    int blockTimeSet;		/* 0 means there is no maximum block
				 * time:  block forever. */
    Tcl_Time blockTime;		/* If blockTimeSet is 1, gives the
				 * maximum elapsed time for the next block. */
    int inTraversal;		/* 1 if Tcl_SetMaxBlockTime is being
				 * called during an event source traversal. */
    EventSource *firstEventSourcePtr;
				/* Pointer to first event source in
				 * global list of event sources. */
} notifier;

/*
 * Declarations for functions used in this file.
 */

static void	InitNotifier _ANSI_ARGS_((void));
static void	NotifierExitHandler _ANSI_ARGS_((ClientData clientData));


/*
 *----------------------------------------------------------------------
 *
 * InitNotifier --
 *
 *	This routine is called to initialize the notifier module.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Creates an exit handler and initializes static data.
 *
 *----------------------------------------------------------------------
 */

static void
InitNotifier()
{
    initialized = 1;
    memset(&notifier, 0, sizeof(notifier));
    notifier.serviceMode = TCL_SERVICE_NONE;
    Tcl_CreateExitHandler(NotifierExitHandler, NULL);
}

/*
 *----------------------------------------------------------------------
 *
 * NotifierExitHandler --
 *
 *	This routine is called during Tcl finalization.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Clears the notifier intialization flag.
 *
 *----------------------------------------------------------------------
 */

static void
NotifierExitHandler(clientData)
    ClientData clientData;  /* Not used. */
{
    initialized = 0;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_CreateEventSource --
 *
 *	This procedure is invoked to create a new source of events.
 *	The source is identified by a procedure that gets invoked
 *	during Tcl_DoOneEvent to check for events on that source
 *	and queue them.
 *
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	SetupProc and checkProc will be invoked each time that Tcl_DoOneEvent
 *	runs out of things to do.  SetupProc will be invoked before
 *	Tcl_DoOneEvent calls select or whatever else it uses to wait
 *	for events.  SetupProc typically calls functions like Tcl_WatchFile
 *	or Tcl_SetMaxBlockTime to indicate what to wait for.
 *
 *	CheckProc is called after select or whatever operation was actually
 *	used to wait.  It figures out whether anything interesting actually
 *	happened (e.g. by calling Tcl_FileReady), and then calls
 *	Tcl_QueueEvent to queue any events that are ready.
 *
 *	Each of these procedures is passed two arguments, e.g.
 *		(*checkProc)(ClientData clientData, int flags));
 *	ClientData is the same as the clientData argument here, and flags
 *	is a combination of things like TCL_FILE_EVENTS that indicates
 *	what events are of interest:  setupProc and checkProc use flags
 *	to figure out whether their events are relevant or not.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_CreateEventSource(setupProc, checkProc, clientData)
    Tcl_EventSetupProc *setupProc;	/* Procedure to invoke to figure out
					 * what to wait for. */
    Tcl_EventCheckProc *checkProc;	/* Procedure to call after waiting
					 * to see what happened. */
    ClientData clientData;		/* One-word argument to pass to
					 * setupProc and checkProc. */
{
    EventSource *sourcePtr;

    if (!initialized) {
	InitNotifier();
    }

    sourcePtr = (EventSource *) ckalloc(sizeof(EventSource));
    sourcePtr->setupProc = setupProc;
    sourcePtr->checkProc = checkProc;
    sourcePtr->clientData = clientData;
    sourcePtr->nextPtr = notifier.firstEventSourcePtr;
    notifier.firstEventSourcePtr = sourcePtr;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DeleteEventSource --
 *
 *	This procedure is invoked to delete the source of events
 *	given by proc and clientData.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The given event source is cancelled, so its procedure will
 *	never again be called.  If no such source exists, nothing
 *	happens.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DeleteEventSource(setupProc, checkProc, clientData)
    Tcl_EventSetupProc *setupProc;	/* Procedure to invoke to figure out
					 * what to wait for. */
    Tcl_EventCheckProc *checkProc;	/* Procedure to call after waiting
					 * to see what happened. */
    ClientData clientData;		/* One-word argument to pass to
					 * setupProc and checkProc. */
{
    EventSource *sourcePtr, *prevPtr;

    for (sourcePtr = notifier.firstEventSourcePtr, prevPtr = NULL;
	    sourcePtr != NULL;
	    prevPtr = sourcePtr, sourcePtr = sourcePtr->nextPtr) {
	if ((sourcePtr->setupProc != setupProc)
		|| (sourcePtr->checkProc != checkProc)
		|| (sourcePtr->clientData != clientData)) {
	    continue;
	}
	if (prevPtr == NULL) {
	    notifier.firstEventSourcePtr = sourcePtr->nextPtr;
	} else {
	    prevPtr->nextPtr = sourcePtr->nextPtr;
	}
	ckfree((char *) sourcePtr);
	return;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_QueueEvent --
 *
 *	Insert an event into the Tk event queue at one of three
 *	positions: the head, the tail, or before a floating marker.
 *	Events inserted before the marker will be processed in
 *	first-in-first-out order, but before any events inserted at
 *	the tail of the queue.  Events inserted at the head of the
 *	queue will be processed in last-in-first-out order.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_QueueEvent(evPtr, position)
    Tcl_Event* evPtr;		/* Event to add to queue.  The storage
				 * space must have been allocated the caller
				 * with malloc (ckalloc), and it becomes
				 * the property of the event queue.  It
				 * will be freed after the event has been
				 * handled. */
    Tcl_QueuePosition position;	/* One of TCL_QUEUE_TAIL, TCL_QUEUE_HEAD,
				 * TCL_QUEUE_MARK. */
{
    if (!initialized) {
	InitNotifier();
    }

    if (position == TCL_QUEUE_TAIL) {
	/*
	 * Append the event on the end of the queue.
	 */

	evPtr->nextPtr = NULL;
	if (notifier.firstEventPtr == NULL) {
	    notifier.firstEventPtr = evPtr;
	} else {
	    notifier.lastEventPtr->nextPtr = evPtr;
	}
	notifier.lastEventPtr = evPtr;
    } else if (position == TCL_QUEUE_HEAD) {
	/*
	 * Push the event on the head of the queue.
	 */

	evPtr->nextPtr = notifier.firstEventPtr;
	if (notifier.firstEventPtr == NULL) {
	    notifier.lastEventPtr = evPtr;
	}	    
	notifier.firstEventPtr = evPtr;
    } else if (position == TCL_QUEUE_MARK) {
	/*
	 * Insert the event after the current marker event and advance
	 * the marker to the new event.
	 */

	if (notifier.markerEventPtr == NULL) {
	    evPtr->nextPtr = notifier.firstEventPtr;
	    notifier.firstEventPtr = evPtr;
	} else {
	    evPtr->nextPtr = notifier.markerEventPtr->nextPtr;
	    notifier.markerEventPtr->nextPtr = evPtr;
	}
	notifier.markerEventPtr = evPtr;
	if (evPtr->nextPtr == NULL) {
	    notifier.lastEventPtr = evPtr;
	}
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_DeleteEvents --
 *
 *	Calls a procedure for each event in the queue and deletes those
 *	for which the procedure returns 1. Events for which the
 *	procedure returns 0 are left in the queue.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Potentially removes one or more events from the event queue.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_DeleteEvents(proc, clientData)
    Tcl_EventDeleteProc *proc;		/* The procedure to call. */
    ClientData clientData;    		/* type-specific data. */
{
    Tcl_Event *evPtr, *prevPtr, *hold;

    if (!initialized) {
	InitNotifier();
    }

    for (prevPtr = (Tcl_Event *) NULL, evPtr = notifier.firstEventPtr;
             evPtr != (Tcl_Event *) NULL;
             ) {
        if ((*proc) (evPtr, clientData) == 1) {
            if (notifier.firstEventPtr == evPtr) {
                notifier.firstEventPtr = evPtr->nextPtr;
                if (evPtr->nextPtr == (Tcl_Event *) NULL) {
                    notifier.lastEventPtr = (Tcl_Event *) NULL;
                }
            } else {
                prevPtr->nextPtr = evPtr->nextPtr;
            }
            hold = evPtr;
            evPtr = evPtr->nextPtr;
            ckfree((char *) hold);
        } else {
            prevPtr = evPtr;
            evPtr = evPtr->nextPtr;
        }
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_ServiceEvent --
 *
 *	Process one event from the event queue, or invoke an
 *	asynchronous event handler.
 *
 * Results:
 *	The return value is 1 if the procedure actually found an event
 *	to process.  If no processing occurred, then 0 is returned.
 *
 * Side effects:
 *	Invokes all of the event handlers for the highest priority
 *	event in the event queue.  May collapse some events into a
 *	single event or discard stale events.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_ServiceEvent(flags)
    int flags;			/* Indicates what events should be processed.
				 * May be any combination of TCL_WINDOW_EVENTS
				 * TCL_FILE_EVENTS, TCL_TIMER_EVENTS, or other
				 * flags defined elsewhere.  Events not
				 * matching this will be skipped for processing
				 * later. */
{
    Tcl_Event *evPtr, *prevPtr;
    Tcl_EventProc *proc;

    if (!initialized) {
	InitNotifier();
    }

    /*
     * Asynchronous event handlers are considered to be the highest
     * priority events, and so must be invoked before we process events
     * on the event queue.
     */
    
    if (Tcl_AsyncReady()) {
	(void) Tcl_AsyncInvoke((Tcl_Interp *) NULL, 0);
	return 1;
    }

    /*
     * No event flags is equivalent to TCL_ALL_EVENTS.
     */
    
    if ((flags & TCL_ALL_EVENTS) == 0) {
	flags |= TCL_ALL_EVENTS;
    }

    /*
     * Loop through all the events in the queue until we find one
     * that can actually be handled.
     */

    for (evPtr = notifier.firstEventPtr; evPtr != NULL;
	 evPtr = evPtr->nextPtr) {
	/*
	 * Call the handler for the event.  If it actually handles the
	 * event then free the storage for the event.  There are two
	 * tricky things here, but stemming from the fact that the event
	 * code may be re-entered while servicing the event:
	 *
	 * 1. Set the "proc" field to NULL.  This is a signal to ourselves
	 *    that we shouldn't reexecute the handler if the event loop
	 *    is re-entered.
	 * 2. When freeing the event, must search the queue again from the
	 *    front to find it.  This is because the event queue could
	 *    change almost arbitrarily while handling the event, so we
	 *    can't depend on pointers found now still being valid when
	 *    the handler returns.
	 */

	proc = evPtr->proc;
	evPtr->proc = NULL;