Optimize color_parse_mem

Commit 5ef8d77a implemented color_parse_mem, a function for
parsing colors from a non-NUL-terminated string, by simply
allocating a new NUL-terminated string and calling
color_parse. This had a small but measurable speed impact on
a user format that used the advanced color parsing. E.g.,

  # uses quick parsing
  $ time ./git log --pretty=tformat:'%Credfoo%Creset' >/dev/null
  real    0m0.673s
  user    0m0.652s
  sys     0m0.016s

  # uses color_parse_mem
  $ time ./git log --pretty=tformat:'%C(red)foo%C(reset)' >/dev/null
  real    0m0.692s
  user    0m0.660s
  sys     0m0.032s

This patch implements color_parse_mem as the primary
function, with color_parse as a wrapper for strings. This
gives comparable timings to the first case above.

Original patch by René. Commit message and debugging by Jeff
King.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/color.c b/color.c
index 54a3da1bad2118815eb8dd1a5f401b67c0879262..915d7a97f67dfd8459e2adc444acab777e503ddd 100644 (file)
--- a/color.c
+++ b/color.c
@@ -40,30 +40,41 @@ static int parse_attr(const char *name, int len)
 }
 
 void color_parse(const char *value, const char *var, char *dst)
+{
+       color_parse_mem(value, strlen(value), var, dst);
+}
+
+void color_parse_mem(const char *value, int value_len, const char *var,
+               char *dst)
 {
        const char *ptr = value;
+       int len = value_len;
        int attr = -1;
        int fg = -2;
        int bg = -2;
 
-       if (!strcasecmp(value, "reset")) {
+       if (!strncasecmp(value, "reset", len)) {
                strcpy(dst, "\033[m");
                return;
        }
 
        /* [fg [bg]] [attr] */
-       while (*ptr) {
+       while (len > 0) {
                const char *word = ptr;
-               int val, len = 0;
+               int val, wordlen = 0;
 
-               while (word[len] && !isspace(word[len]))
-                       len++;
+               while (len > 0 && !isspace(word[wordlen])) {
+                       wordlen++;
+                       len--;
+               }
 
-               ptr = word + len;
-               while (*ptr && isspace(*ptr))
+               ptr = word + wordlen;
+               while (len > 0 && isspace(*ptr)) {
                        ptr++;
+                       len--;
+               }
 
-               val = parse_color(word, len);
+               val = parse_color(word, wordlen);
                if (val >= -1) {
                        if (fg == -2) {
                                fg = val;
@@ -75,7 +86,7 @@ void color_parse(const char *value, const char *var, char *dst)
                        }
                        goto bad;
                }
-               val = parse_attr(word, len);
+               val = parse_attr(word, wordlen);
                if (val < 0 || attr != -1)
                        goto bad;
                attr = val;
@@ -115,7 +126,7 @@ void color_parse(const char *value, const char *var, char *dst)
        *dst = 0;
        return;
 bad:
-       die("bad color value '%s' for variable '%s'", value, var);
+       die("bad color value '%.*s' for variable '%s'", value_len, value, var);
 }
 
 int git_config_colorbool(const char *var, const char *value, int stdout_is_tty)
@@ -191,10 +202,3 @@ int color_fprintf_ln(FILE *fp, const char *color, const char *fmt, ...)
        va_end(args);
        return r;
 }
-
-void color_parse_mem(const char *value, int len, const char *var, char *dst)
-{
-       char *tmp = xmemdupz(value, len);
-       color_parse(tmp, var, dst);
-       free(tmp);
-}