--- /dev/null
+/* Efficient caching of X GCs (graphics contexts).
+ Copyright (C) 1993 Free Software Foundation, Inc.
+ Copyright (C) 1994, 1995 Board of Trustees, University of Illinois.
+
+This file is part of XEmacs.
+
+XEmacs is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2, or (at your option) any
+later version.
+
+XEmacs is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with XEmacs; see the file COPYING. If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA. */
+
+/* Synched up with: Not in FSF. */
+
+/* Emacs uses a lot of different display attributes; for example, assume
+ that only four fonts are in use (normal, bold, italic, and bold-italic).
+ Then assume that one stipple or background is used for text selections,
+ and another is used for highlighting mousable regions. That makes 16
+ GCs already. Add in the fact that another GC may be needed to display
+ the text cursor in any of those regions, and you've got 32. Add in
+ more fonts, and it keeps increasing exponentially.
+
+ We used to keep these GCs in a cache of merged (fully qualified) faces.
+ However, a lot of other code in xterm.c used XChangeGC of existing GCs,
+ which is kind of slow and kind of random. Also, managing the face cache
+ was tricky because it was hard to know when a face was no longer visible
+ on the frame -- we had to mark all frames as garbaged whenever a face
+ was changed, which caused an unpleasant amount of flicker (since faces are
+ created/destroyed (= changed) whenever a frame is created/destroyed.
+
+ So this code maintains a cache at the GC level instead of at the face
+ level. There is an upper limit on the size of the cache, after which we
+ will stop creating GCs and start reusing them (reusing the least-recently-
+ used ones first). So if faces get changed, their GCs will eventually be
+ recycled. Also more sharing of GCs is possible.
+
+ This code uses hashtables. It could be that, if the cache size is small
+ enough, a linear search might be faster; but I doubt it, since we need
+ `equal' comparisons, not `eq', and I expect that the optimal cache size
+ will be ~100.
+
+ Written by jwz, 14 jun 93
+ */
+
+#include <config.h>
+#include <X11/Xlib.h>
+#include "xgccache.h"
+
+
+#define GC_CACHE_SIZE 100
+
+#define GCCACHE_HASH
+
+
+#ifdef GCCACHE_HASH
+#include "lisp.h"
+#include "hash.h"
+#endif
+
+struct gcv_and_mask {
+ XGCValues gcv;
+ unsigned long mask;
+};
+
+struct gc_cache_cell {
+ GC gc;
+ struct gcv_and_mask gcvm;
+ struct gc_cache_cell *prev, *next;
+};
+
+struct gc_cache {
+ Display *dpy; /* used only as arg to XCreateGC/XFreeGC */
+ Window window; /* used only as arg to XCreateGC */
+ int size;
+ struct gc_cache_cell *head;
+ struct gc_cache_cell *tail;
+#ifdef GCCACHE_HASH
+ c_hashtable table;
+#endif
+
+ int create_count;
+ int delete_count;
+};
+
+#ifdef GCCACHE_HASH
+static unsigned long
+gc_cache_hash (CONST void *arg)
+{
+ CONST struct gcv_and_mask *gcvm = (CONST struct gcv_and_mask *) arg;
+ unsigned long *longs = (unsigned long *) &gcvm->gcv;
+ unsigned long hash = gcvm->mask;
+ int i;
+ /* This could look at the mask and only use the used slots in the
+ hash code. That would win in that we wouldn't have to initialize
+ every slot of the gcv when calling gc_cache_lookup. But we need
+ the hash function to be as fast as possible; some timings should
+ be done. */
+ for (i = 0; i < (sizeof (XGCValues) / sizeof (unsigned long)); i++)
+ hash = (hash<<1) ^ *longs++;
+ return hash;
+}
+
+#endif /* GCCACHE_HASH */
+
+static int
+gc_cache_eql (CONST void *arg1, CONST void *arg2)
+{
+ /* See comment in gc_cache_hash */
+ return !memcmp (arg1, arg2, sizeof (struct gcv_and_mask));
+}
+
+struct gc_cache *
+make_gc_cache (Display *dpy, Window window)
+{
+ struct gc_cache *cache = xnew (struct gc_cache);
+ cache->dpy = dpy;
+ cache->window = window;
+ cache->size = 0;
+ cache->head = cache->tail = 0;
+ cache->create_count = cache->delete_count = 0;
+#ifdef GCCACHE_HASH
+ cache->table =
+ make_general_hashtable (GC_CACHE_SIZE, gc_cache_hash, gc_cache_eql);
+#endif
+ return cache;
+}
+
+void
+free_gc_cache (struct gc_cache *cache)
+{
+ struct gc_cache_cell *rest, *next;
+ rest = cache->head;
+ while (rest)
+ {
+ XFreeGC (cache->dpy, rest->gc);
+ next = rest->next;
+ xfree (rest);
+ rest = next;
+ }
+#ifdef GCCACHE_HASH
+ free_hashtable (cache->table);
+#endif
+ xfree (cache);
+}
+
+GC
+gc_cache_lookup (struct gc_cache *cache, XGCValues *gcv, unsigned long mask)
+{
+ struct gc_cache_cell *cell, *next, *prev;
+ struct gcv_and_mask gcvm;
+
+ if ((!!cache->head) != (!!cache->tail)) abort ();
+ if (cache->head && (cache->head->prev || cache->tail->next)) abort ();
+
+ gcvm.mask = mask;
+ gcvm.gcv = *gcv; /* this copies... */
+
+#ifdef GCCACHE_HASH
+
+ if (gethash (&gcvm, cache->table, (CONST void **) &cell))
+
+#else /* !GCCACHE_HASH */
+
+ cell = cache->tail; /* start at the end (most recently used) */
+ while (cell)
+ {
+ if (gc_cache_eql (&gcvm, &cell->gcvm))
+ break;
+ else
+ cell = cell->prev;
+ }
+
+ /* #### This whole file needs some serious overhauling. */
+ if (!(mask | GCTile) && cell->gc->values.tile)
+ cell = 0;
+ else if (!(mask | GCStipple) && cell->gc->values.stipple)
+ cell = 0;
+
+ if (cell)
+
+#endif /* !GCCACHE_HASH */
+
+ {
+ /* Found a cell. Move this cell to the end of the list, so that it
+ will be less likely to be collected than a cell that was accessed
+ less recently.
+ */
+ if (cell == cache->tail)
+ return cell->gc;
+
+ next = cell->next;
+ prev = cell->prev;
+ if (prev) prev->next = next;
+ if (next) next->prev = prev;
+ if (cache->head == cell) cache->head = next;
+ cell->next = 0;
+ cell->prev = cache->tail;
+ cache->tail->next = cell;
+ cache->tail = cell;
+ if (cache->head == cell) abort ();
+ if (cell->next) abort ();
+ if (cache->head->prev) abort ();
+ if (cache->tail->next) abort ();
+ return cell->gc;
+ }
+
+ /* else, cache miss. */
+
+ if (cache->size == GC_CACHE_SIZE)
+ /* Reuse the first cell on the list (least-recently-used).
+ Remove it from the list, and unhash it from the table.
+ */
+ {
+ cell = cache->head;
+ cache->head = cell->next;
+ cache->head->prev = 0;
+ if (cache->tail == cell) cache->tail = 0; /* only one */
+ XFreeGC (cache->dpy, cell->gc);
+ cache->delete_count++;
+#ifdef GCCACHE_HASH
+ remhash (&cell->gcvm, cache->table);
+#endif
+ }
+ else if (cache->size > GC_CACHE_SIZE)
+ abort ();
+ else
+ {
+ /* Allocate a new cell (don't put it in the list or table yet). */
+ cell = xnew (struct gc_cache_cell);
+ cache->size++;
+ }
+
+ /* Now we've got a cell (new or reused). Fill it in. */
+ memcpy (&cell->gcvm.gcv, gcv, sizeof (XGCValues));
+ cell->gcvm.mask = mask;
+
+ /* Put the cell on the end of the list. */
+ cell->next = 0;
+ cell->prev = cache->tail;
+ if (cache->tail) cache->tail->next = cell;
+ cache->tail = cell;
+ if (! cache->head) cache->head = cell;
+
+ cache->create_count++;
+#ifdef GCCACHE_HASH
+ /* Hash it in the table */
+ puthash (&cell->gcvm, cell, cache->table);
+#endif
+
+ /* Now make and return the GC. */
+ cell->gc = XCreateGC (cache->dpy, cache->window, mask, gcv);
+
+ /* debug */
+ assert (cell->gc == gc_cache_lookup (cache, gcv, mask));
+
+ return cell->gc;
+}
+
+\f
+#ifdef DEBUG_XEMACS
+
+#include <stdio.h>
+
+void describe_gc_cache (struct gc_cache *cache);
+void
+describe_gc_cache (struct gc_cache *cache)
+{
+ int count = 0;
+ struct gc_cache_cell *cell = cache->head;
+ stderr_out ("\nsize: %d", cache->size);
+ stderr_out ("\ncreated: %d", cache->create_count);
+ stderr_out ("\ndeleted: %d", cache->delete_count);
+ while (cell)
+ {
+ struct gc_cache_cell *cell2;
+ int i = 0;
+ stderr_out ("\n%d:\t0x%lx GC: 0x%08lx hash: 0x%08lx\n",
+ count, (long) cell, (long) cell->gc, gc_cache_hash (&cell->gcvm));
+ for (cell2 = cache->head; cell2; cell2 = cell2->next, i++)
+ if (count != i &&
+ gc_cache_hash (&cell->gcvm) == gc_cache_hash (&cell2->gcvm))
+ stderr_out ("\tHASH COLLISION with cell %d\n", i);
+ stderr_out ("\tmask: %8lx\n", cell->gcvm.mask);
+#define F(x) (int)cell->gcvm.gcv.x
+#define G(w,x) if (F(x) != (~0)) stderr_out ("\t%-12s%8x\n", w, F(x))
+ G("function:", function);
+ G("plane_mask:", plane_mask);
+ G("foreground:", foreground);
+ G("background:", background);
+ G("line_width:", line_width);
+ G("line_style:", line_style);
+ G("cap_style:", cap_style);
+ G("join_style:", join_style);
+ G("fill_style:", fill_style);
+ G("fill_rule:", fill_rule);
+ G("arc_mode:", arc_mode);
+ G("tile:", tile);
+ G("stipple:", stipple);
+ G("tsx_origin:", ts_x_origin);
+ G("tsy_origin:", ts_y_origin);
+ G("font:", font);
+ G("subwindow:", subwindow_mode);
+ G("gexposures:", graphics_exposures);
+ G("clip_x:", clip_x_origin);
+ G("clip_y:", clip_y_origin);
+ G("clip_mask:", clip_mask);
+ G("dash_off:", dash_offset);
+#undef F
+#undef G
+ count++;
+ if (cell->next && cell == cache->tail)
+ stderr_out ("\nERROR! tail is here!\n\n");
+ else if (!cell->next && cell != cache->tail)
+ stderr_out ("\nERROR! tail is not at the end\n\n");
+ cell = cell->next;
+ }
+ if (count != cache->size)
+ stderr_out ("\nERROR! count should be %d\n\n", cache->size);
+}
+
+#endif /* DEBUG_XEMACS */
projects / chise / xemacs-chise.git.1 / blobdiff