[hackers] [dmenu] drw: minor improvement to the nomatches cache || NRK

From: <git_AT_suckless.org>
Date: Fri, 7 Jul 2023 15:01:06 +0200 (CEST)

commit 7ab0cb5ef0e19352fc5d64ae0d57a5cf4540acbf
Author: NRK <nrk_AT_disroot.org>
AuthorDate: Fri Jul 7 17:00:42 2023 +0600
Commit: Hiltjo Posthuma <hiltjo_AT_codemadness.org>
CommitDate: Fri Jul 7 15:03:57 2023 +0200

    drw: minor improvement to the nomatches cache
    
    1. use `unsigned int` to store the codepoints, this avoids waste on
       common case where `long` is 64bits. and POSIX guarantees `int` to be
       at least 32bits so there's no risk of truncation.
    2. since switching to `unsigned int` cuts down the memory requirement by
       half, double the cache size from 64 to 128.
    3. instead of a linear search, use a simple hash-table for O(1) lookups.

diff --git a/dmenu.c b/dmenu.c
index 62f1089..40f93e0 100644
--- a/dmenu.c
+++ b/dmenu.c
_AT_@ -22,7 +22,6 @@
 /* macros */
 #define INTERSECT(x,y,w,h,r) (MAX(0, MIN((x)+(w),(r).x_org+(r).width) - MAX((x),(r).x_org)) \
                              * MAX(0, MIN((y)+(h),(r).y_org+(r).height) - MAX((y),(r).y_org)))
-#define LENGTH(X) (sizeof X / sizeof X[0])
 #define TEXTW(X) (drw_fontset_getwidth(drw, (X)) + lrpad)
 
 /* enums */
diff --git a/drw.c b/drw.c
index a58a2b4..78a2b27 100644
--- a/drw.c
+++ b/drw.c
_AT_@ -238,8 +238,8 @@ drw_rect(Drw *drw, int x, int y, unsigned int w, unsigned int h, int filled, int
 int
 drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int lpad, const char *text, int invert)
 {
- int i, ty, ellipsis_x = 0;
- unsigned int tmpw, ew, ellipsis_w = 0, ellipsis_len;
+ int ty, ellipsis_x = 0;
+ unsigned int tmpw, ew, ellipsis_w = 0, ellipsis_len, hash, h0, h1;
         XftDraw *d = NULL;
         Fnt *usedfont, *curfont, *nextfont;
         int utf8strlen, utf8charlen, render = x || y || w || h;
_AT_@ -251,9 +251,7 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int lp
         XftResult result;
         int charexists = 0, overflow = 0;
         /* keep track of a couple codepoints for which we have no match. */
- enum { nomatches_len = 64 };
- static struct { long codepoint[nomatches_len]; unsigned int idx; } nomatches;
- static unsigned int ellipsis_width = 0;
+ static unsigned int nomatches[128], ellipsis_width;
 
         if (!drw || (render && (!drw->scheme || !w)) || !text || !drw->fonts)
                 return 0;
_AT_@ -338,11 +336,14 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int lp
                          * character must be drawn. */
                         charexists = 1;
 
- for (i = 0; i < nomatches_len; ++i) {
- /* avoid calling XftFontMatch if we know we won't find a match */
- if (utf8codepoint == nomatches.codepoint[i])
- goto no_match;
- }
+ hash = (unsigned int)utf8codepoint;
+ hash = ((hash >> 16) ^ hash) * 0x21F0AAAD;
+ hash = ((hash >> 15) ^ hash) * 0xD35A2D97;
+ h0 = ((hash >> 15) ^ hash) % LENGTH(nomatches);
+ h1 = (hash >> 17) % LENGTH(nomatches);
+ /* avoid expensive XftFontMatch call when we know we won't find a match */
+ if (nomatches[h0] == utf8codepoint || nomatches[h1] == utf8codepoint)
+ goto no_match;
 
                         fccharset = FcCharSetCreate();
                         FcCharSetAddChar(fccharset, utf8codepoint);
_AT_@ -371,7 +372,7 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int lp
                                         curfont->next = usedfont;
                                 } else {
                                         xfont_free(usedfont);
- nomatches.codepoint[++nomatches.idx % nomatches_len] = utf8codepoint;
+ nomatches[nomatches[h0] ? h1 : h0] = utf8codepoint;
 no_match:
                                         usedfont = drw->fonts;
                                 }
diff --git a/util.h b/util.h
index f633b51..c0a50d4 100644
--- a/util.h
+++ b/util.h
_AT_@ -3,6 +3,7 @@
 #define MAX(A, B) ((A) > (B) ? (A) : (B))
 #define MIN(A, B) ((A) < (B) ? (A) : (B))
 #define BETWEEN(X, A, B) ((A) <= (X) && (X) <= (B))
+#define LENGTH(X) (sizeof (X) / sizeof (X)[0])
 
 void die(const char *fmt, ...);
 void *ecalloc(size_t nmemb, size_t size);
Received on Fri Jul 07 2023 - 15:01:06 CEST