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[OPTIM] halog: make fgets parse more bytes by blocks 

By adding a "landing area" at the end of the buffer, it becomes safe to
parse more bytes at once. On 32-bit this makes fgets run about 4% faster
but it does not save anything on 64-bit.
This commit is contained in:
Willy Tarreau 2011-09-10 10:25:05 +02:00
parent e8c7ecc2dd
commit 31a02e9c5b
2 changed files with 17 additions and 11 deletions
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12
contrib/halog/fgets2-64.c
View File

@ -58,7 +58,7 @@ static inline unsigned long long has_zero64(unsigned long long x)
#define FGETS2_BUFSIZE (256*1024)
const char *fgets2(FILE *stream)
{
static char buffer[FGETS2_BUFSIZE + 9]; // +9 to have zeroes past the end
static char buffer[FGETS2_BUFSIZE + 68];
static char *end = buffer;
static char *line = buffer;
@ -73,7 +73,7 @@ const char *fgets2(FILE *stream)
* time.
*/
if (next <= (end-12)) {
if (next <= end) {
/* max 3 bytes tested here */
while ((((unsigned long)next) & 3) && *next != '\n')
next++;
@ -115,8 +115,8 @@ const char *fgets2(FILE *stream)
if (!has_zero(*(unsigned int *)next ^ 0x0A0A0A0AU))
next += 4;
/* we finish if needed. Note that next might be slightly higher
* than end here because we might have gone past it above.
/* We finish if needed : if <next> is below <end>, it means we
* found an LF in one of the 4 following bytes.
*/
while (next < end) {
if (*next == '\n') {
@ -131,7 +131,8 @@ const char *fgets2(FILE *stream)
/* we found an incomplete line. First, let's move the
* remaining part of the buffer to the beginning, then
* try to complete the buffer with a new read.
* try to complete the buffer with a new read. We can't
* rely on <next> anymore because it went past <end>.
*/
if (line > buffer) {
if (end != line)
@ -156,6 +157,7 @@ const char *fgets2(FILE *stream)
}
end += ret;
*end = '\n'; /* make parser stop ASAP */
/* search for '\n' again */
}
}

16
contrib/halog/fgets2.c
View File

@ -47,7 +47,7 @@ static inline unsigned int has_zero(unsigned int x)
#define FGETS2_BUFSIZE (256*1024)
const char *fgets2(FILE *stream)
{
static char buffer[FGETS2_BUFSIZE + 5];
static char buffer[FGETS2_BUFSIZE + 32];
static char *end = buffer;
static char *line = buffer;
@ -64,8 +64,10 @@ const char *fgets2(FILE *stream)
while (next < end && (((unsigned long)next) & 3) && *next != '\n')
next++;
/* now next is multiple of 4 or equal to end */
while (next <= (end-32)) {
/* Now next is multiple of 4 or equal to end. We know we can safely
* read up to 32 bytes past end if needed because they're allocated.
*/
while (next < end) {
if (has_zero(*(unsigned int *)next ^ 0x0A0A0A0A))
break;
next += 4;
@ -92,8 +94,8 @@ const char *fgets2(FILE *stream)
next += 4;
}
/* we finish if needed. Note that next might be slightly higher
* than end here because we might have gone past it above.
/* We finish if needed : if <next> is below <end>, it means we
* found an LF in one of the 4 following bytes.
*/
while (next < end) {
if (*next == '\n') {
@ -108,7 +110,8 @@ const char *fgets2(FILE *stream)
/* we found an incomplete line. First, let's move the
* remaining part of the buffer to the beginning, then
* try to complete the buffer with a new read.
* try to complete the buffer with a new read. We can't
* rely on <next> anymore because it went past <end>.
*/
if (line > buffer) {
if (end != line)
@ -133,6 +136,7 @@ const char *fgets2(FILE *stream)
}
end += ret;
*end = '\n'; /* make parser stop ASAP */
/* search for '\n' again */
}
}