PKGBUILDs/core/grep/65-dfa-optional.patch

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2009-10-10 02:17:35 +00:00
The DFA algorithm is slow with mutlibytes characters.
This patch disables the DFA algorithm, but it can be re-enabled by setting
the GREP_USE_DFA environment variable.
This patch requires 64-egf-speedup.patch
--- a/src/search.c.orig 2005-09-06 22:22:17.000000000 +0200
+++ b/src/search.c 2005-09-06 22:25:41.000000000 +0200
@@ -326,6 +326,8 @@
char eol = eolbyte;
int backref, start, len;
struct kwsmatch kwsm;
+ static int use_dfa;
+ static int use_dfa_checked = 0;
size_t i, ret_val;
#ifdef MBS_SUPPORT
int mb_cur_max = MB_CUR_MAX;
@@ -333,6 +335,26 @@
memset (&mbs, '\0', sizeof (mbstate_t));
#endif /* MBS_SUPPORT */
+ if (!use_dfa_checked)
+ {
+ char *grep_use_dfa = getenv ("GREP_USE_DFA");
+ if (!grep_use_dfa)
+ {
+#ifdef MBS_SUPPORT
+ /* Turn off DFA when processing multibyte input. */
+ use_dfa = (MB_CUR_MAX == 1);
+#else
+ use_dfa = 1;
+#endif /* MBS_SUPPORT */
+ }
+ else
+ {
+ use_dfa = atoi (grep_use_dfa);
+ }
+
+ use_dfa_checked = 1;
+ }
+
buflim = buf + size;
for (beg = end = buf; end < buflim; beg = end)
@@ -400,7 +422,8 @@
#endif /* MBS_SUPPORT */
(kwsm.index < kwset_exact_matches))
goto success;
- if (dfaexec (&dfa, beg, end - beg, &backref) == (size_t) -1)
+ if (use_dfa &&
+ dfaexec (&dfa, beg, end - beg, &backref) == (size_t) -1)
continue;
}
else
@@ -409,7 +432,9 @@
#ifdef MBS_SUPPORT
size_t bytes_left = 0;
#endif /* MBS_SUPPORT */
- size_t offset = dfaexec (&dfa, beg, buflim - beg, &backref);
+ size_t offset = 0;
+ if (use_dfa)
+ offset = dfaexec (&dfa, beg, buflim - beg, &backref);
if (offset == (size_t) -1)
break;
/* Narrow down to the line we've found. */
@@ -451,7 +476,7 @@
--beg;
}
/* Successful, no backreferences encountered! */
- if (!backref)
+ if (use_dfa && !backref)
goto success;
}
else