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stk/Tcl/tclNotify.c

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/*
* 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;
if ((proc != NULL) && (*proc)(evPtr, flags)) {
if (notifier.firstEventPtr == evPtr) {
notifier.firstEventPtr = evPtr->nextPtr;
if (evPtr->nextPtr == NULL) {
notifier.lastEventPtr = NULL;
}
if (notifier.markerEventPtr == evPtr) {
notifier.markerEventPtr = NULL;
}
} else {
for (prevPtr = notifier.firstEventPtr;
prevPtr->nextPtr != evPtr; prevPtr = prevPtr->nextPtr) {
/* Empty loop body. */
}
prevPtr->nextPtr = evPtr->nextPtr;
if (evPtr->nextPtr == NULL) {
notifier.lastEventPtr = prevPtr;
}
if (notifier.markerEventPtr == evPtr) {
notifier.markerEventPtr = prevPtr;
}
}
ckfree((char *) evPtr);
return 1;
} else {
/*
* The event wasn't actually handled, so we have to restore
* the proc field to allow the event to be attempted again.
*/
evPtr->proc = proc;
}
/*
* The handler for this event asked to defer it. Just go on to
* the next event.
*/
continue;
}
return 0;
}
/*
*----------------------------------------------------------------------
*
* Tcl_GetServiceMode --
*
* This routine returns the current service mode of the notifier.
*
* Results:
* Returns either TCL_SERVICE_ALL or TCL_SERVICE_NONE.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
int
Tcl_GetServiceMode()
{
if (!initialized) {
InitNotifier();
}
return notifier.serviceMode;
}
/*
*----------------------------------------------------------------------
*
* Tcl_SetServiceMode --
*
* This routine sets the current service mode of the notifier.
*
* Results:
* Returns the previous service mode.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
int
Tcl_SetServiceMode(mode)
int mode; /* New service mode: TCL_SERVICE_ALL or
* TCL_SERVICE_NONE */
{
int oldMode;
if (!initialized) {
InitNotifier();
}
oldMode = notifier.serviceMode;
notifier.serviceMode = mode;
return oldMode;
}
/*
*----------------------------------------------------------------------
*
* Tcl_SetMaxBlockTime --
*
* This procedure is invoked by event sources to tell the notifier
* how long it may block the next time it blocks. The timePtr
* argument gives a maximum time; the actual time may be less if
* some other event source requested a smaller time.
*
* Results:
* None.
*
* Side effects:
* May reduce the length of the next sleep in the notifier.
*
*----------------------------------------------------------------------
*/
void
Tcl_SetMaxBlockTime(timePtr)
Tcl_Time *timePtr; /* Specifies a maximum elapsed time for
* the next blocking operation in the
* event notifier. */
{
if (!initialized) {
InitNotifier();
}
if (!notifier.blockTimeSet || (timePtr->sec < notifier.blockTime.sec)
|| ((timePtr->sec == notifier.blockTime.sec)
&& (timePtr->usec < notifier.blockTime.usec))) {
notifier.blockTime = *timePtr;
notifier.blockTimeSet = 1;
}
/*
* If we are called outside an event source traversal, set the
* timeout immediately.
*/
if (!notifier.inTraversal) {
if (notifier.blockTimeSet) {
Tcl_SetTimer(&notifier.blockTime);
} else {
Tcl_SetTimer(NULL);
}
}
}
/*
*----------------------------------------------------------------------
*
* Tcl_DoOneEvent --
*
* Process a single event of some sort. If there's no work to
* do, wait for an event to occur, then process it.
*
* Results:
* The return value is 1 if the procedure actually found an event
* to process. If no processing occurred, then 0 is returned (this
* can happen if the TCL_DONT_WAIT flag is set or if there are no
* event handlers to wait for in the set specified by flags).
*
* Side effects:
* May delay execution of process while waiting for an event,
* unless TCL_DONT_WAIT is set in the flags argument. Event
* sources are invoked to check for and queue events. Event
* handlers may produce arbitrary side effects.
*
*----------------------------------------------------------------------
*/
int
Tcl_DoOneEvent(flags)
int flags; /* Miscellaneous flag values: may be any
* combination of TCL_DONT_WAIT,
* TCL_WINDOW_EVENTS, TCL_FILE_EVENTS,
* TCL_TIMER_EVENTS, TCL_IDLE_EVENTS, or
* others defined by event sources. */
{
int result = 0, oldMode;
EventSource *sourcePtr;
Tcl_Time *timePtr;
if (!initialized) {
InitNotifier();
}
/*
* The first thing we do is to service any asynchronous event
* handlers.
*/
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;
}
/*
* Set the service mode to none so notifier event routines won't
* try to service events recursively.
*/
oldMode = notifier.serviceMode;
notifier.serviceMode = TCL_SERVICE_NONE;
/*
* The core of this procedure is an infinite loop, even though
* we only service one event. The reason for this is that we
* may be processing events that don't do anything inside of Tcl.
*/
while (1) {
/*
* If idle events are the only things to service, skip the
* main part of the loop and go directly to handle idle
* events (i.e. don't wait even if TCL_DONT_WAIT isn't set).
*/
if ((flags & TCL_ALL_EVENTS) == TCL_IDLE_EVENTS) {
flags = TCL_IDLE_EVENTS|TCL_DONT_WAIT;
goto idleEvents;
}
/*
* Ask Tcl to service a queued event, if there are any.
*/
if (Tcl_ServiceEvent(flags)) {
result = 1;
break;
}
/*
* If TCL_DONT_WAIT is set, be sure to poll rather than
* blocking, otherwise reset the block time to infinity.
*/
if (flags & TCL_DONT_WAIT) {
notifier.blockTime.sec = 0;
notifier.blockTime.usec = 0;
notifier.blockTimeSet = 1;
} else {
notifier.blockTimeSet = 0;
}
/*
* Set up all the event sources for new events. This will
* cause the block time to be updated if necessary.
*/
notifier.inTraversal = 1;
for (sourcePtr = notifier.firstEventSourcePtr; sourcePtr != NULL;
sourcePtr = sourcePtr->nextPtr) {
if (sourcePtr->setupProc) {
(sourcePtr->setupProc)(sourcePtr->clientData, flags);
}
}
notifier.inTraversal = 0;
if ((flags & TCL_DONT_WAIT) || notifier.blockTimeSet) {
timePtr = &notifier.blockTime;
} else {
timePtr = NULL;
}
/*
* Wait for a new event or a timeout. If Tcl_WaitForEvent
* returns -1, we should abort Tcl_DoOneEvent.
*/
result = Tcl_WaitForEvent(timePtr);
if (result < 0) {
result = 0;
break;
}
/*
* Check all the event sources for new events.
*/
for (sourcePtr = notifier.firstEventSourcePtr; sourcePtr != NULL;
sourcePtr = sourcePtr->nextPtr) {
if (sourcePtr->checkProc) {
(sourcePtr->checkProc)(sourcePtr->clientData, flags);
}
}
/*
* Check for events queued by the notifier or event sources.
*/
if (Tcl_ServiceEvent(flags)) {
result = 1;
break;
}
/*
* We've tried everything at this point, but nobody we know
* about had anything to do. Check for idle events. If none,
* either quit or go back to the top and try again.
*/
idleEvents:
if (flags & TCL_IDLE_EVENTS) {
if (TclServiceIdle()) {
result = 1;
break;
}
}
if (flags & TCL_DONT_WAIT) {
break;
}
/*
* If Tcl_WaitForEvent has returned 1,
* indicating that one system event has been dispatched
* (and thus that some Tcl code might have been indirectly executed),
* we break out of the loop.
* We do this to give VwaitCmd for instance a chance to check
* if that system event had the side effect of changing the
* variable (so the vwait can return and unwind properly).
*
* NB: We will process idle events if any first, because
* otherwise we might never do the idle events if the notifier
* always gets system events.
*/
if (result) {
break;
}
}
notifier.serviceMode = oldMode;
return result;
}
/*
*----------------------------------------------------------------------
*
* Tcl_ServiceAll --
*
* This routine checks all of the event sources, processes
* events that are on the Tcl event queue, and then calls the
* any idle handlers. Platform specific notifier callbacks that
* generate events should call this routine before returning to
* the system in order to ensure that Tcl gets a chance to
* process the new events.
*
* Results:
* Returns 1 if an event or idle handler was invoked, else 0.
*
* Side effects:
* Anything that an event or idle handler may do.
*
*----------------------------------------------------------------------
*/
int
Tcl_ServiceAll()
{
int result = 0;
EventSource *sourcePtr;
if (!initialized) {
InitNotifier();
}
if (notifier.serviceMode == TCL_SERVICE_NONE) {
return result;
}
/*
* We need to turn off event servicing like we to in Tcl_DoOneEvent,
* to avoid recursive calls.
*/
notifier.serviceMode = TCL_SERVICE_NONE;
/*
* Check async handlers first.
*/
if (Tcl_AsyncReady()) {
(void) Tcl_AsyncInvoke((Tcl_Interp *) NULL, 0);
}
/*
* Make a single pass through all event sources, queued events,
* and idle handlers. Note that we wait to update the notifier
* timer until the end so we can avoid multiple changes.
*/
notifier.inTraversal = 1;
notifier.blockTimeSet = 0;
for (sourcePtr = notifier.firstEventSourcePtr; sourcePtr != NULL;
sourcePtr = sourcePtr->nextPtr) {
if (sourcePtr->setupProc) {
(sourcePtr->setupProc)(sourcePtr->clientData, TCL_ALL_EVENTS);
}
}
for (sourcePtr = notifier.firstEventSourcePtr; sourcePtr != NULL;
sourcePtr = sourcePtr->nextPtr) {
if (sourcePtr->checkProc) {
(sourcePtr->checkProc)(sourcePtr->clientData, TCL_ALL_EVENTS);
}
}
while (Tcl_ServiceEvent(0)) {
result = 1;
}
if (TclServiceIdle()) {
result = 1;
}
if (!notifier.blockTimeSet) {
Tcl_SetTimer(NULL);
} else {
Tcl_SetTimer(&notifier.blockTime);
}
notifier.inTraversal = 0;
notifier.serviceMode = TCL_SERVICE_ALL;
return result;
}
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