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Avoid overhead of comparision function pointer calls in lpFind() (#13503)

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In #13279 (found by @filipecosta90), for custom lookups, we introduce a
comparison function for `lpFind()` to compare entry, but it also
introduces some overhead.

To avoid the overhead of function pointer calls:
1. Extract the lpFindCb() method into a lpFindCbInternal() method that
is easier to inline.
2. Use unlikely to annotate the comparison method, as can only success
once.

---------

Co-authored-by: Ozan Tezcan <ozantezcan@gmail.com>
This commit is contained in:
debing.sun
2024-09-03 22:53:13 +08:00
committed by GitHub
parent fb8755a636
commit de7f2f87f7
1 changed files with 10 additions and 4 deletions
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14
src/listpack.c
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@@ -687,8 +687,8 @@ int lpGetIntegerValue(unsigned char *p, long long *lval) {
* will be returned. 'user' is passed to this callback.
* Skip 'skip' entries between every comparison.
* Returns NULL when the field could not be found. */
unsigned char *lpFindCb(unsigned char *lp, unsigned char *p,
void *user, lpCmp cmp, unsigned int skip)
static inline unsigned char *lpFindCbInternal(unsigned char *lp, unsigned char *p,
void *user, lpCmp cmp, unsigned int skip)
{
int skipcnt = 0;
unsigned char *value;
@@ -707,7 +707,7 @@ unsigned char *lpFindCb(unsigned char *lp, unsigned char *p,
assert(p >= lp + LP_HDR_SIZE && p + entry_size < lp + lp_bytes);
}
if (cmp(lp, p, user, value, ll) == 0)
if (unlikely(cmp(lp, p, user, value, ll) == 0))
return p;
/* Reset skip count */
@@ -734,6 +734,12 @@ unsigned char *lpFindCb(unsigned char *lp, unsigned char *p,
return NULL;
}
unsigned char *lpFindCb(unsigned char *lp, unsigned char *p,
void *user, lpCmp cmp, unsigned int skip)
{
return lpFindCbInternal(lp, p, user, cmp, skip);
}
struct lpFindArg {
unsigned char *s; /* Item to search */
uint32_t slen; /* Item len */
@@ -787,7 +793,7 @@ unsigned char *lpFind(unsigned char *lp, unsigned char *p, unsigned char *s,
.s = s,
.slen = slen
};
return lpFindCb(lp, p, &arg, lpFindCmp, skip);
return lpFindCbInternal(lp, p, &arg, lpFindCmp, skip);
}
/* Insert, delete or replace the specified string element 'elestr' of length