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OPTIM: http: optimize lookup of comma and quote in header values

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http_find_header2() relies on find_hdr_value_end() to find the comma
delimiting a header field value, which also properly handles double
quotes and backslashes within quotes. In fact double quotes are very
rare, and commas happen once every multiple characters, especially
with cookies where a full block can be found at once. So it makes
sense to optimize this function to speed up the lookup of the first
block before the quote.

This change increases the performance from 212k to 217k req/s when
requests contain a 1kB cookie (+2.5%). We don't care about going
back into the fast parser after the first quote, as it may
needlessly make the parser more complex for very marginal gains.
This commit is contained in:
Willy Tarreau 2016-11-05 18:23:38 +01:00
parent 5f10ea30f4
commit e6d9c21059
1 changed files with 19 additions and 0 deletions
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19
src/proto_http.c
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@ -836,6 +836,25 @@ char *find_hdr_value_end(char *s, const char *e)
int quoted, qdpair;
quoted = qdpair = 0;
#if defined(__x86_64__) || \
defined(__i386__) || defined(__i486__) || defined(__i586__) || defined(__i686__) || \
defined(__ARM_ARCH_7A__)
/* speedup: skip everything not a comma nor a double quote */
for (; s <= e - sizeof(int); s += sizeof(int)) {
unsigned int c = *(int *)s; // comma
unsigned int q = c; // quote
c ^= 0x2c2c2c2c; // contains one zero on a comma
q ^= 0x22222222; // contains one zero on a quote
c = (c - 0x01010101) & ~c; // contains 0x80 below a comma
q = (q - 0x01010101) & ~q; // contains 0x80 below a quote
if ((c | q) & 0x80808080)
break; // found a comma or a quote
}
#endif
for (; s < e; s++) {
if (qdpair) qdpair = 0;
else if (quoted) {