summaryrefslogtreecommitdiffstats
path: root/unix/tkUnixXId.c
blob: c2be14594f137a491161343b930c0879d65ecacb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
/* 
 * tkUnixXId.c --
 *
 *	This file provides a replacement function for the default X
 *	resource allocator (_XAllocID).  The problem with the default
 *	allocator is that it never re-uses ids, which causes long-lived
 *	applications to crash when X resource identifiers wrap around.
 *	The replacement functions in this file re-use old identifiers
 *	to prevent this problem.
 *
 *	The code in this file is based on similar implementations by
 *	George C. Kaplan and Michael Hoegeman.
 *
 * Copyright (c) 1993 The Regents of the University of California.
 * Copyright (c) 1994-1997 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: tkUnixXId.c,v 1.6 2001/09/25 16:25:20 dgp Exp $
 */

/*
 * The definition below is needed on some systems so that we can access
 * the resource_alloc field of Display structures in order to replace
 * the resource allocator.
 */

#define XLIB_ILLEGAL_ACCESS 1

#include "tkUnixInt.h"
#include "tkPort.h"

/*
 * A structure of the following type is used to hold one or more
 * available resource identifiers.  There is a list of these structures
 * for each display.
 */

#define IDS_PER_STACK 10
typedef struct TkIdStack {
    XID ids[IDS_PER_STACK];		/* Array of free identifiers. */
    int numUsed;			/* Indicates how many of the entries
					 * in ids are currently in use. */
    TkDisplay *dispPtr;			/* Display to which ids belong. */
    struct TkIdStack *nextPtr;		/* Next bunch of free identifiers
					 * for the same display. */
} TkIdStack;

/*
 * Forward declarations for procedures defined in this file:
 */

static XID		AllocXId _ANSI_ARGS_((Display *display));
static Tk_RestrictAction CheckRestrictProc _ANSI_ARGS_((
			    ClientData clientData, XEvent *eventPtr));
static void		WindowIdCleanup _ANSI_ARGS_((ClientData clientData));
static void		WindowIdCleanup2 _ANSI_ARGS_((ClientData clientData));

/*
 *----------------------------------------------------------------------
 *
 * TkInitXId --
 *
 *	This procedure is called to initialize the id allocator for
 *	a given display.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The official allocator for the display is set up to be AllocXId.
 *
 *----------------------------------------------------------------------
 */

void
TkInitXId(dispPtr)
    TkDisplay *dispPtr;			/* Tk's information about the
					 * display. */
{
    dispPtr->idStackPtr = NULL;
    dispPtr->defaultAllocProc = (XID (*) _ANSI_ARGS_((Display *display))) 
            dispPtr->display->resource_alloc;
    dispPtr->display->resource_alloc = AllocXId;
    dispPtr->windowStackPtr = NULL;
    dispPtr->idCleanupScheduled = 0;
}

/*
 *----------------------------------------------------------------------
 *
 * AllocXId --
 *
 *	This procedure is invoked by Xlib as the resource allocator
 *	for a display.
 *
 * Results:
 *	The return value is an X resource identifier that isn't currently
 *	in use.
 *
 * Side effects:
 *	The identifier is removed from the stack of free identifiers,
 *	if it was previously on the stack.
 *
 *----------------------------------------------------------------------
 */

static XID
AllocXId(display)
    Display *display;			/* Display for which to allocate. */
{
    TkDisplay *dispPtr;
    TkIdStack *stackPtr;

    /*
     * Find Tk's information about the display.
     */

    dispPtr = TkGetDisplay(display);
    
    /*
     * If the topmost chunk on the stack is empty then free it.  Then
     * check for a free id on the stack and return it if it exists.
     */

    stackPtr = dispPtr->idStackPtr;
    if (stackPtr != NULL) {
	while (stackPtr->numUsed == 0) {
	    dispPtr->idStackPtr = stackPtr->nextPtr;
	    ckfree((char *) stackPtr);
	    stackPtr = dispPtr->idStackPtr;
	    if (stackPtr == NULL) {
		goto defAlloc;
	    }
	}
	stackPtr->numUsed--;
	return stackPtr->ids[stackPtr->numUsed];
    }

    /*
     * No free ids in the stack:  just get one from the default
     * allocator.
     */

    defAlloc:
    return (*dispPtr->defaultAllocProc)(display);
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_FreeXId --
 *
 *	This procedure is called to indicate that an X resource identifier
 *	is now free.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The identifier is added to the stack of free identifiers for its
 *	display, so that it can be re-used.
 *
 *----------------------------------------------------------------------
 */

void
Tk_FreeXId(display, xid)
    Display *display;			/* Display for which xid was
					 * allocated. */
    XID xid;				/* Identifier that is no longer
					 * in use. */
{
    TkDisplay *dispPtr;
    TkIdStack *stackPtr;

    /*
     * Find Tk's information about the display.
     */

    dispPtr = TkGetDisplay(display);

    /*
     * Add a new chunk to the stack if the current chunk is full.
     */
    
    stackPtr = dispPtr->idStackPtr;
    if ((stackPtr == NULL) || (stackPtr->numUsed >= IDS_PER_STACK)) {
	stackPtr = (TkIdStack *) ckalloc(sizeof(TkIdStack));
	stackPtr->numUsed = 0;
	stackPtr->dispPtr = dispPtr;
	stackPtr->nextPtr = dispPtr->idStackPtr;
	dispPtr->idStackPtr = stackPtr;
    }

    /*
     * Add the id to the current chunk.
     */

    stackPtr->ids[stackPtr->numUsed] = xid;
    stackPtr->numUsed++;
}

/*
 *----------------------------------------------------------------------
 *
 * TkFreeWindowId --
 *
 *	This procedure is invoked instead of TkFreeXId for window ids.
 *	See below for the reason why.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The id given by w will eventually be freed, so that it can be
 *	reused for other resources.
 *
 * Design:
 *	Freeing window ids is very tricky because there could still be
 *	events pending for a window in the event queue (or even in the
 *	server) at the time the window is destroyed.  If the window
 *	id were to get reused immediately for another window, old
 *	events could "drop in" on the new window, causing unexpected
 *	behavior.
 *
 *	Thus we have to wait to re-use a window id until we know that
 *	there are no events left for it.  Right now this is done in
 *	two steps.  First, we wait until we know that the server
 *	has seen the XDestroyWindow request, so we can be sure that
 *	it won't generate more events for the window and that any
 *	existing events are in our queue.  Second, we make sure that
 *	there are no events whatsoever in our queue (this is conservative
 *	but safe).
 *
 * 	The first step is done by remembering the request id of the
 *	XDestroyWindow request and using LastKnownRequestProcessed to
 *	see what events the server has processed.  If multiple windows
 *	get destroyed at about the same time, we just remember the
 *	most recent request number for any of them (again, conservative
 *	but safe).
 *
 *	There are a few other complications as well.  When Tk destroys a
 *	sub-tree of windows, it only issues a single XDestroyWindow call,
 *	at the very end for the root of the subtree.  We can't free any of
 *	the window ids until the final XDestroyWindow call.  To make sure
 *	that this happens, we have to keep track of deletions in progress,
 *	hence the need for the "destroyCount" field of the display.
 *
 *	One final problem.  Some servers, like Sun X11/News servers still
 *	seem to have problems with ids getting reused too quickly.  I'm
 *	not completely sure why this is a problem, but delaying the
 *	recycling of ids appears to eliminate it.  Therefore, we wait
 *	an additional few seconds, even after "the coast is clear"
 *	before reusing the ids.
 *
 *----------------------------------------------------------------------
 */

void
TkFreeWindowId(dispPtr, w)
    TkDisplay *dispPtr;		/* Display that w belongs to. */
    Window w;			/* X identifier for window on dispPtr. */
{
    TkIdStack *stackPtr;

    /*
     * Put the window id on a separate stack of window ids, rather
     * than the main stack, so it won't get reused right away.  Add
     * a new chunk to the stack if the current chunk is full.
     */

    stackPtr = dispPtr->windowStackPtr;
    if ((stackPtr == NULL) || (stackPtr->numUsed >= IDS_PER_STACK)) {
	stackPtr = (TkIdStack *) ckalloc(sizeof(TkIdStack));
	stackPtr->numUsed = 0;
	stackPtr->dispPtr = dispPtr;
	stackPtr->nextPtr = dispPtr->windowStackPtr;
	dispPtr->windowStackPtr = stackPtr;
    }

    /*
     * Add the id to the current chunk.
     */

    stackPtr->ids[stackPtr->numUsed] = w;
    stackPtr->numUsed++;

    /*
     * Schedule a call to WindowIdCleanup if one isn't already
     * scheduled.
     */

    if (!dispPtr->idCleanupScheduled) {
	dispPtr->idCleanupScheduled = 1;
	Tcl_CreateTimerHandler(100, WindowIdCleanup, (ClientData) dispPtr);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * WindowIdCleanup --
 *
 *	See if we can now free up all the accumulated ids of
 *	deleted windows.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	If it's safe to move the window ids back to the main free
 *	list, we schedule this to happen after a few mores seconds
 *	of delay.  If it's not safe to move them yet, a timer handler
 *	gets invoked to try again later.
 *
 *----------------------------------------------------------------------
 */

static void
WindowIdCleanup(clientData)
    ClientData clientData;	/* Pointer to TkDisplay for display */
{
    TkDisplay *dispPtr = (TkDisplay *) clientData;
    int anyEvents, delta;
    Tk_RestrictProc *oldProc;
    ClientData oldData;
    static Tcl_Time timeout = {0, 0};

    dispPtr->idCleanupScheduled = 0;

    /*
     * See if it's safe to recycle the window ids.  It's safe if:
     * (a) no deletions are in progress.
     * (b) the server has seen all of the requests up to the last
     *     XDestroyWindow request.
     * (c) there are no events in the event queue; the only way to
     *     test for this right now is to create a restrict proc that
     *     will filter the events, then call Tcl_DoOneEvent to see if
     *	   the procedure gets invoked.
     */

    if (dispPtr->destroyCount > 0) {
	goto tryAgain;
    }
    delta = LastKnownRequestProcessed(dispPtr->display)
	    - dispPtr->lastDestroyRequest;
    if (delta < 0) {
	XSync(dispPtr->display, False);
    }
    anyEvents = 0;
    oldProc = Tk_RestrictEvents(CheckRestrictProc, (ClientData) &anyEvents,
	    &oldData);
    TkUnixDoOneXEvent(&timeout);
    Tk_RestrictEvents(oldProc, oldData, &oldData);
    if (anyEvents) {
	goto tryAgain;
    }

    /*
     * These ids look safe to recycle, but we still need to delay a bit
     * more (see comments for TkFreeWindowId).  Schedule the final freeing.
     */

    if (dispPtr->windowStackPtr != NULL) {
	Tcl_CreateTimerHandler(5000, WindowIdCleanup2,
		(ClientData) dispPtr->windowStackPtr);
	dispPtr->windowStackPtr = NULL;
    }
    return;

    /*
     * It's still not safe to free up the ids.  Try again a bit later.
     */

    tryAgain:
    dispPtr->idCleanupScheduled = 1;
    Tcl_CreateTimerHandler(500, WindowIdCleanup, (ClientData) dispPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * WindowIdCleanup2 --
 *
 *	This procedure is the last one in the chain that recycles
 *	window ids.  It takes all of the ids indicated by its
 *	argument and adds them back to the main id free list.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Window ids get added to the main free list for their display.
 *
 *----------------------------------------------------------------------
 */

static void
WindowIdCleanup2(clientData)
    ClientData clientData;	/* Pointer to TkIdStack list. */
{
    TkIdStack *stackPtr = (TkIdStack *) clientData;
    TkIdStack *lastPtr;

    lastPtr = stackPtr;
    while (lastPtr->nextPtr != NULL) {
	lastPtr = lastPtr->nextPtr;
    }
    lastPtr->nextPtr = stackPtr->dispPtr->idStackPtr;
    stackPtr->dispPtr->idStackPtr = stackPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * CheckRestrictProc --
 *
 *	This procedure is a restrict procedure, called by Tcl_DoOneEvent
 *	to filter X events.  All it does is to set a flag to indicate
 *	that there are X events present.
 *
 * Results:
 *	Sets the integer pointed to by the argument, then returns
 *	TK_DEFER_EVENT.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static Tk_RestrictAction
CheckRestrictProc(clientData, eventPtr)
    ClientData clientData;	/* Pointer to flag to set. */
    XEvent *eventPtr;		/* Event to filter;  not used. */
{
    int *flag = (int *) clientData;
    *flag = 1;
    return TK_DEFER_EVENT;
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_GetPixmap --
 *
 *	Same as the XCreatePixmap procedure except that it manages
 *	resource identifiers better.
 *
 * Results:
 *	Returns a new pixmap.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

Pixmap
Tk_GetPixmap(display, d, width, height, depth)
    Display *display;		/* Display for new pixmap. */
    Drawable d;			/* Drawable where pixmap will be used. */
    int width, height;		/* Dimensions of pixmap. */
    int depth;			/* Bits per pixel for pixmap. */
{
    return XCreatePixmap(display, d, (unsigned) width, (unsigned) height,
	    (unsigned) depth);
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_FreePixmap --
 *
 *	Same as the XFreePixmap procedure except that it also marks
 *	the resource identifier as free.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The pixmap is freed in the X server and its resource identifier
 *	is saved for re-use.
 *
 *----------------------------------------------------------------------
 */

void
Tk_FreePixmap(display, pixmap)
    Display *display;		/* Display for which pixmap was allocated. */
    Pixmap pixmap;		/* Identifier for pixmap. */
{
    XFreePixmap(display, pixmap);
    Tk_FreeXId(display, (XID) pixmap);
}

/*
 *----------------------------------------------------------------------
 *
 * TkpWindowWasRecentlyDeleted --
 *
 *	Checks whether the window was recently deleted. This is called
 *	by the generic error handler to detect asynchronous notification
 *	of errors due to operations by Tk on a window that was already
 *	deleted by the server.
 *
 * Results:
 *	1 if the window was deleted recently, 0 otherwise.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
TkpWindowWasRecentlyDeleted(win, dispPtr)
    Window win;		/* The window to check for. */
    TkDisplay *dispPtr;	/* The window belongs to this display. */
{
    TkIdStack *stackPtr;
    int i;

    for (stackPtr = dispPtr->windowStackPtr;
         stackPtr != NULL;
         stackPtr = stackPtr->nextPtr) {
        for (i = 0; i < stackPtr->numUsed; i++) {
            if ((Window) stackPtr->ids[i] == win) {
                return 1;
            }
        }
    }
    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * TkpScanWindowId --
 *
 *	Given a string, produce the corresponding Window Id.
 *
 * Results:
 *      The return value is normally TCL_OK;  in this case *idPtr
 *      will be set to the Window value equivalent to string.  If
 *      string is improperly formed then TCL_ERROR is returned and
 *      an error message will be left in the interp's result.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

int
TkpScanWindowId(interp, string, idPtr)
    Tcl_Interp *interp;	
    CONST char *string;
    Window *idPtr;
{
    int value;
    if (Tcl_GetInt(interp, string, &value) != TCL_OK) {
	return TCL_ERROR;
    }
    *idPtr = (Window) value;
    return TCL_OK;
}