sal/rtl/ustring.cxx | 24 ++++++++++++++++++------
1 file changed, 18 insertions(+), 6 deletions(-)
New commits:
commit bb9d628552d7a91680ef04c08b1f49cee4ada6bf
Author: Norbert Thiebaud <nthieb...@gmail.com>
Date: Sat Jul 4 21:02:35 2015 -0500
performance tuning of rtl_ustr_indexOfAscii_WithLength()
lcov over make check showed
98 4699997 : sal_Int32 rtl_ustr_indexOfAscii_WithLength(
99 : sal_Unicode const * str, sal_Int32 len,
100 : char const * subStr, sal_Int32 subLen)
SAL_THROW_EXTERN_C()
101 : {
102 4699997 : assert(len >= 0);
103 4699997 : assert(subLen >= 0);
104 4699997 : if (subLen > 0 && subLen <= len) {
105 : sal_Int32 i;
106 54014537 : for (i = 0; i <= len - subLen; ++i) {
107 51036513 : if (rtl_ustr_asciil_reverseEquals_WithLength(
108 51036523 : str + i, subStr, subLen))
109 : {
110 205482 : return i;
111 : }
112 : }
113 : }
114 4494505 : return -1;
115 : }
so
1/ in 95% of the cases the result is not-found.. _that_ is the hot path
2/ we are calling rtl_ustr_asciil_reverseEquals_WithLength close to 11 times
per call.. (average ~ len - subLen, due to the high miss ratio)
so let's first search for the first byte of the substring
to optimize the 'miss' case, which is the most common one.
Change-Id: I20ef0821db2ff0db5935dd562844a947a14aff64
Reviewed-on: https://gerrit.libreoffice.org/16763
Tested-by: Jenkins <c...@libreoffice.org>
Reviewed-by: Stephan Bergmann <sberg...@redhat.com>
diff --git a/sal/rtl/ustring.cxx b/sal/rtl/ustring.cxx
index b31bc2f..9648fc6 100644
--- a/sal/rtl/ustring.cxx
+++ b/sal/rtl/ustring.cxx
@@ -27,6 +27,7 @@
#include <cstdlib>
#include <limits>
#include <stdexcept>
+#include <string>
#include <osl/diagnose.h>
#include <osl/interlck.h>
@@ -101,14 +102,25 @@ sal_Int32 rtl_ustr_indexOfAscii_WithLength(
{
assert(len >= 0);
assert(subLen >= 0);
- if (subLen > 0 && subLen <= len) {
- sal_Int32 i;
- for (i = 0; i <= len - subLen; ++i) {
- if (rtl_ustr_asciil_reverseEquals_WithLength(
- str + i, subStr, subLen))
+ if (subLen > 0 && subLen <= len)
+ {
+ sal_Unicode const* end = str + len;
+ sal_Unicode const* cursor = str;
+
+ while(cursor < end)
+ {
+ cursor = std::char_traits<sal_Unicode>::find(cursor, end - cursor,
*subStr);
+ if(!cursor || (end - cursor < subLen))
{
- return i;
+ /* no enough left to actually have a match */
+ break;
+ }
+ /* now it is worth trying a full match */
+ if (rtl_ustr_asciil_reverseEquals_WithLength(cursor, subStr,
subLen))
+ {
+ return cursor - str;
}
+ cursor += 1;
}
}
return -1;
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