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authorEon S. Jeon <esjeon@lavabit.com>2013-07-19 01:07:02 -0400
committerRoberto E. Vargas Caballero <k0ga@shike2.com>2013-07-19 08:38:10 +0200
commit33ad83d49213749f4fcec850327f57a33ca8b921 (patch)
tree264341fa0a2e832b95af7d92753e30c1faf894da
parent40e4d76d227d9c517054036f546acd49431bca42 (diff)
downloadst-33ad83d49213749f4fcec850327f57a33ca8b921.tar.gz
Improved font caching
I made a patch that improves the performance of font caching mechanism. This is based on a funny behaviour of FontConfig: it was handling FcCharSet in a somewhat unexpected way. So, we are currently adding "a character" to a new FcCharSet, and then add it to a FcPattern. However, if we toss the FcPattern to FontConfig, it loads the entire language(charset) that contains the character we gave. That is, we don't always have to load a new font for each unknown character. Instead, we can reused cached fonts, and this significantly reduces the number of calls to extremely slow FontConfig matching functions. One more thing. I found that, in libXft, there's a function called XftCharExists. XftCharIndex internally calls this function, and does more stuffs if the character does exist. Since the returned index is never used in st, we should call XftCharExists instead of XftCharIndex. Please note that I already made this change in the patch.
-rw-r--r--st.c63
1 files changed, 22 insertions, 41 deletions
diff --git a/st.c b/st.c
index 289ecb8..947373f 100644
--- a/st.c
+++ b/st.c
@@ -462,17 +462,12 @@ enum {
typedef struct {
XftFont *font;
- long c;
int flags;
} Fontcache;
-/*
- * Fontcache is a ring buffer, with frccur as current position and frclen as
- * the current length of used elements.
- */
-
-static Fontcache frc[1024];
-static int frccur = -1, frclen = 0;
+/* Fontcache is an array now. A new font will be appended to the array. */
+static Fontcache frc[16];
+static int frclen = 0;
ssize_t
xwrite(int fd, char *s, size_t len) {
@@ -2781,18 +2776,12 @@ xunloadfont(Font *f) {
void
xunloadfonts(void) {
- int i, ip;
+ int i;
- /*
- * Free the loaded fonts in the font cache. This is done backwards
- * from the frccur.
- */
- for(i = 0, ip = frccur; i < frclen; i++, ip--) {
- if(ip < 0)
- ip = LEN(frc) - 1;
- XftFontClose(xw.dpy, frc[ip].font);
+ /* Free the loaded fonts in the font cache. */
+ for(i = 0; i < frclen; i++) {
+ XftFontClose(xw.dpy, frc[i].font);
}
- frccur = -1;
frclen = 0;
xunloadfont(&dc.font);
@@ -2918,7 +2907,7 @@ void
xdraws(char *s, Glyph base, int x, int y, int charlen, int bytelen) {
int winx = borderpx + x * xw.cw, winy = borderpx + y * xw.ch,
width = charlen * xw.cw, xp, i;
- int frp, frcflags;
+ int frcflags;
int u8fl, u8fblen, u8cblen, doesexist;
char *u8c, *u8fs;
long u8char;
@@ -3044,7 +3033,7 @@ xdraws(char *s, Glyph base, int x, int y, int charlen, int bytelen) {
s += u8cblen;
bytelen -= u8cblen;
- doesexist = XftCharIndex(xw.dpy, font->match, u8char);
+ doesexist = XftCharExists(xw.dpy, font->match, u8char);
if(!doesexist || bytelen <= 0) {
if(bytelen <= 0) {
if(doesexist) {
@@ -3071,14 +3060,10 @@ xdraws(char *s, Glyph base, int x, int y, int charlen, int bytelen) {
if(doesexist)
break;
- frp = frccur;
/* Search the font cache. */
- for(i = 0; i < frclen; i++, frp--) {
- if(frp <= 0)
- frp = LEN(frc) - 1;
-
- if(frc[frp].c == u8char
- && frc[frp].flags == frcflags) {
+ for(i = 0; i < frclen; i++) {
+ if(XftCharExists(xw.dpy, frc[i].font, u8char)
+ && frc[i].flags == frcflags) {
break;
}
}
@@ -3113,28 +3098,24 @@ xdraws(char *s, Glyph base, int x, int y, int charlen, int bytelen) {
/*
* Overwrite or create the new cache entry.
*/
- frccur++;
- frclen++;
- if(frccur >= LEN(frc))
- frccur = 0;
- if(frclen > LEN(frc)) {
- frclen = LEN(frc);
- XftFontClose(xw.dpy, frc[frccur].font);
+ if(frclen >= LEN(frc)) {
+ frclen = LEN(frc) - 1;
+ XftFontClose(xw.dpy, frc[frclen].font);
}
- frc[frccur].font = XftFontOpenPattern(xw.dpy,
+ frc[frclen].font = XftFontOpenPattern(xw.dpy,
fontpattern);
- frc[frccur].c = u8char;
- frc[frccur].flags = frcflags;
+ frc[frclen].flags = frcflags;
+
+ i = frclen;
+ frclen++;
FcPatternDestroy(fcpattern);
FcCharSetDestroy(fccharset);
-
- frp = frccur;
}
- XftDrawStringUtf8(xw.draw, fg, frc[frp].font,
- xp, winy + frc[frp].font->ascent,
+ XftDrawStringUtf8(xw.draw, fg, frc[i].font,
+ xp, winy + frc[i].font->ascent,
(FcChar8 *)u8c, u8cblen);
xp += font->width;