582 lines
16 KiB
C
582 lines
16 KiB
C
/*
|
||
* tclNotify.c --
|
||
*
|
||
* This file provides the parts of the Tcl event notifier that are
|
||
* the same on all platforms, plus a few other parts that are used
|
||
* on more than one platform but not all.
|
||
*
|
||
* The notifier is the lowest-level part of the event system. It
|
||
* manages an event queue that holds Tcl_Event structures and a list
|
||
* of event sources that can add events to the queue. It also
|
||
* contains the procedure Tcl_DoOneEvent that invokes the event
|
||
* sources and blocks to wait for new events, but Tcl_DoOneEvent
|
||
* is in the platform-specific part of the notifier (in files like
|
||
* tclUnixNotify.c).
|
||
*
|
||
* Copyright (c) 1995 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 1.7 96/09/19 16:40:16
|
||
*/
|
||
|
||
#include "tclInt.h"
|
||
#include "tclPort.h"
|
||
|
||
/*
|
||
* The following variable records the address of the first event
|
||
* source in the list of all event sources for the application.
|
||
* This variable is accessed by the notifier to traverse the list
|
||
* and invoke each event source.
|
||
*/
|
||
|
||
TclEventSource *tclFirstEventSourcePtr = NULL;
|
||
|
||
/*
|
||
* The following variables indicate how long to block in the event
|
||
* notifier the next time it blocks (default: block forever).
|
||
*/
|
||
|
||
static int blockTimeSet = 0; /* 0 means there is no maximum block
|
||
* time: block forever. */
|
||
static Tcl_Time blockTime; /* If blockTimeSet is 1, gives the
|
||
* maximum elapsed time for the next block. */
|
||
|
||
/*
|
||
* The following variables 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 Tcl_Event *firstEventPtr = NULL;
|
||
/* First pending event, or NULL if none. */
|
||
static Tcl_Event *lastEventPtr = NULL;
|
||
/* Last pending event, or NULL if none. */
|
||
static Tcl_Event *markerEventPtr = NULL;
|
||
/* Last high-priority event in queue, or
|
||
* NULL if none. */
|
||
|
||
/*
|
||
* Prototypes for procedures used only in this file:
|
||
*/
|
||
|
||
static int ServiceEvent _ANSI_ARGS_((int flags));
|
||
|
||
/*
|
||
*----------------------------------------------------------------------
|
||
*
|
||
* 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. */
|
||
{
|
||
TclEventSource *sourcePtr;
|
||
|
||
sourcePtr = (TclEventSource *) ckalloc(sizeof(TclEventSource));
|
||
sourcePtr->setupProc = setupProc;
|
||
sourcePtr->checkProc = checkProc;
|
||
sourcePtr->clientData = clientData;
|
||
sourcePtr->nextPtr = tclFirstEventSourcePtr;
|
||
tclFirstEventSourcePtr = 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. */
|
||
{
|
||
TclEventSource *sourcePtr, *prevPtr;
|
||
|
||
for (sourcePtr = tclFirstEventSourcePtr, prevPtr = NULL;
|
||
sourcePtr != NULL;
|
||
prevPtr = sourcePtr, sourcePtr = sourcePtr->nextPtr) {
|
||
if ((sourcePtr->setupProc != setupProc)
|
||
|| (sourcePtr->checkProc != checkProc)
|
||
|| (sourcePtr->clientData != clientData)) {
|
||
continue;
|
||
}
|
||
if (prevPtr == NULL) {
|
||
tclFirstEventSourcePtr = 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 (position == TCL_QUEUE_TAIL) {
|
||
/*
|
||
* Append the event on the end of the queue.
|
||
*/
|
||
|
||
evPtr->nextPtr = NULL;
|
||
if (firstEventPtr == NULL) {
|
||
firstEventPtr = evPtr;
|
||
} else {
|
||
lastEventPtr->nextPtr = evPtr;
|
||
}
|
||
lastEventPtr = evPtr;
|
||
} else if (position == TCL_QUEUE_HEAD) {
|
||
/*
|
||
* Push the event on the head of the queue.
|
||
*/
|
||
|
||
evPtr->nextPtr = firstEventPtr;
|
||
if (firstEventPtr == NULL) {
|
||
lastEventPtr = evPtr;
|
||
}
|
||
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 (markerEventPtr == NULL) {
|
||
evPtr->nextPtr = firstEventPtr;
|
||
firstEventPtr = evPtr;
|
||
} else {
|
||
evPtr->nextPtr = markerEventPtr->nextPtr;
|
||
markerEventPtr->nextPtr = evPtr;
|
||
}
|
||
markerEventPtr = evPtr;
|
||
if (evPtr->nextPtr == NULL) {
|
||
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;
|
||
|
||
for (prevPtr = (Tcl_Event *) NULL, evPtr = firstEventPtr;
|
||
evPtr != (Tcl_Event *) NULL;
|
||
) {
|
||
if ((*proc) (evPtr, clientData) == 1) {
|
||
if (firstEventPtr == evPtr) {
|
||
firstEventPtr = evPtr->nextPtr;
|
||
if (evPtr->nextPtr == (Tcl_Event *) NULL) {
|
||
lastEventPtr = (Tcl_Event *) NULL;
|
||
}
|
||
} else {
|
||
prevPtr->nextPtr = evPtr->nextPtr;
|
||
}
|
||
hold = evPtr;
|
||
evPtr = evPtr->nextPtr;
|
||
ckfree((char *) hold);
|
||
} else {
|
||
prevPtr = evPtr;
|
||
evPtr = evPtr->nextPtr;
|
||
}
|
||
}
|
||
}
|
||
|
||
/*
|
||
*----------------------------------------------------------------------
|
||
*
|
||
* ServiceEvent --
|
||
*
|
||
* Process one event from the event queue. This routine is called
|
||
* by the notifier whenever it wants Tk to process an event.
|
||
*
|
||
* 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.
|
||
*
|
||
*----------------------------------------------------------------------
|
||
*/
|
||
|
||
static int
|
||
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;
|
||
|
||
/*
|
||
* 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 = 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 (firstEventPtr == evPtr) {
|
||
firstEventPtr = evPtr->nextPtr;
|
||
if (evPtr->nextPtr == NULL) {
|
||
lastEventPtr = NULL;
|
||
}
|
||
if (markerEventPtr == evPtr) {
|
||
markerEventPtr = NULL;
|
||
}
|
||
} else {
|
||
for (prevPtr = firstEventPtr; prevPtr->nextPtr != evPtr;
|
||
prevPtr = prevPtr->nextPtr) {
|
||
/* Empty loop body. */
|
||
}
|
||
prevPtr->nextPtr = evPtr->nextPtr;
|
||
if (evPtr->nextPtr == NULL) {
|
||
lastEventPtr = prevPtr;
|
||
}
|
||
if (markerEventPtr == evPtr) {
|
||
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_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 (!blockTimeSet || (timePtr->sec < blockTime.sec)
|
||
|| ((timePtr->sec == blockTime.sec)
|
||
&& (timePtr->usec < blockTime.usec))) {
|
||
blockTime = *timePtr;
|
||
blockTimeSet = 1;
|
||
}
|
||
}
|
||
|
||
/*
|
||
*----------------------------------------------------------------------
|
||
*
|
||
* 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. */
|
||
{
|
||
TclEventSource *sourcePtr;
|
||
Tcl_Time *timePtr;
|
||
|
||
/*
|
||
* No event flags is equivalent to TCL_ALL_EVENTS.
|
||
*/
|
||
|
||
if ((flags & TCL_ALL_EVENTS) == 0) {
|
||
flags |= TCL_ALL_EVENTS;
|
||
}
|
||
|
||
/*
|
||
* The core of this procedure is an infinite loop, even though
|
||
* we only service one event. The reason for this is that we
|
||
* might think we have an event ready (e.g. the connection to
|
||
* the server becomes readable), but then we might discover that
|
||
* there's nothing interesting on that connection, so no event
|
||
* was serviced. Or, the select operation could return prematurely
|
||
* due to a signal. The easiest thing in both these cases is
|
||
* just to loop back and try again.
|
||
*/
|
||
|
||
while (1) {
|
||
|
||
/*
|
||
* The first thing we do is to service any asynchronous event
|
||
* handlers.
|
||
*/
|
||
|
||
if (Tcl_AsyncReady()) {
|
||
(void) Tcl_AsyncInvoke((Tcl_Interp *) NULL, 0);
|
||
return 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_IDLE_EVENTS) {
|
||
flags = TCL_IDLE_EVENTS|TCL_DONT_WAIT;
|
||
goto idleEvents;
|
||
}
|
||
|
||
/*
|
||
* Ask Tk to service a queued event, if there are any.
|
||
*/
|
||
|
||
if (ServiceEvent(flags)) {
|
||
return 1;
|
||
}
|
||
|
||
/*
|
||
* There are no events already queued. Invoke all of the
|
||
* event sources to give them a chance to setup for the wait.
|
||
*/
|
||
|
||
blockTimeSet = 0;
|
||
for (sourcePtr = tclFirstEventSourcePtr; sourcePtr != NULL;
|
||
sourcePtr = sourcePtr->nextPtr) {
|
||
(*sourcePtr->setupProc)(sourcePtr->clientData, flags);
|
||
}
|
||
if ((flags & TCL_DONT_WAIT) ||
|
||
((flags & TCL_IDLE_EVENTS) && TclIdlePending())) {
|
||
/*
|
||
* Don't block: there are idle events waiting, or we don't
|
||
* care about idle events anyway, or the caller asked us not
|
||
* to block.
|
||
*/
|
||
|
||
blockTime.sec = 0;
|
||
blockTime.usec = 0;
|
||
timePtr = &blockTime;
|
||
} else if (blockTimeSet) {
|
||
timePtr = &blockTime;
|
||
} else {
|
||
timePtr = NULL;
|
||
}
|
||
|
||
/*
|
||
* Wait until an event occurs or the timer expires.
|
||
*/
|
||
|
||
if (Tcl_WaitForEvent(timePtr) == TCL_ERROR) {
|
||
return 0;
|
||
}
|
||
|
||
/*
|
||
* Give each of the event sources a chance to queue events,
|
||
* then call ServiceEvent and give it another chance to
|
||
* service events.
|
||
*/
|
||
|
||
for (sourcePtr = tclFirstEventSourcePtr; sourcePtr != NULL;
|
||
sourcePtr = sourcePtr->nextPtr) {
|
||
(*sourcePtr->checkProc)(sourcePtr->clientData, flags);
|
||
}
|
||
if (ServiceEvent(flags)) {
|
||
return 1;
|
||
}
|
||
|
||
/*
|
||
* We've tried everything at this point, but nobody 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) && TclServiceIdle()) {
|
||
return 1;
|
||
}
|
||
if (flags & TCL_DONT_WAIT) {
|
||
return 0;
|
||
}
|
||
}
|
||
}
|