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perf: speed up msgpack_extract/lookup on the map hot path #12

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Merged
khanaffan merged 1 commit into from
Jul 1, 2026
Merged

perf: speed up msgpack_extract/lookup on the map hot path #12

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29 changes: 17 additions & 12 deletions src/msgpack.c
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Original file line number Diff line number Diff line change
Expand Up @@ -404,6 +404,12 @@ static u32 mpSkipOneD(const u8 *a, u32 n, u32 i, int depth){
if( b <= 0x7f ) return i;
/* negative fixint */
if( b >= 0xe0 ) return i;
/* fixstr: 0xa0-0xbf — checked early; it is the most common element type
** (all map keys plus short strings) on the extract/lookup hot path. */
if( (b & 0xe0) == 0xa0 ){
u32 sz = b & 0x1f;
return (i+sz<=n)?i+sz:0;
}

switch( b ){
/* fixed-length scalars */
Expand Down Expand Up @@ -505,11 +511,7 @@ static u32 mpSkipOneD(const u8 *a, u32 n, u32 i, int depth){
for( j=0; j<count; j++ ){ i = mpSkipOneD(a,n,i,depth+1); if(!i&&j<count-1) return 0; }
return i;
}
/* fixstr: 0xa0-0xbf */
if( (b & 0xe0) == 0xa0 ){
u32 sz = b & 0x1f;
return (i+sz<=n)?i+sz:0;
}
/* fixstr (0xa0-0xbf) is handled early, before the switch. */
return 0;
}

Expand Down Expand Up @@ -715,20 +717,23 @@ static int mpLookup(
for( j=0; j<count && !found; j++ ){
u8 kb;
const char *kStr = 0;
u32 kLen = 0, valOff;
u32 kLen = 0, valOff = 0;
if( iCur >= n ) return SQLITE_ERROR;
kb = a[iCur];
/* Decode the key header and derive the value offset directly, avoiding a
** redundant mpSkipOne() over the (string) key on this hot lookup path. */
if( kb >= 0xa0 && kb <= 0xbf ){
kLen = kb & 0x1f; kStr = (const char*)(a+iCur+1);
kLen = kb & 0x1f; kStr = (const char*)(a+iCur+1); valOff = iCur+1+kLen;
} else if( kb == MP_STR8 && iCur+2 <= n ){
kLen = a[iCur+1]; kStr = (const char*)(a+iCur+2);
kLen = a[iCur+1]; kStr = (const char*)(a+iCur+2); valOff = iCur+2+kLen;
} else if( kb == MP_STR16 && iCur+3 <= n ){
kLen = mpRead16(a+iCur+1); kStr = (const char*)(a+iCur+3);
kLen = mpRead16(a+iCur+1); kStr = (const char*)(a+iCur+3); valOff = iCur+3+kLen;
} else if( kb == MP_STR32 && iCur+5 <= n ){
kLen = mpRead32(a+iCur+1); kStr = (const char*)(a+iCur+5);
kLen = mpRead32(a+iCur+1); kStr = (const char*)(a+iCur+5); valOff = iCur+5+kLen;
} else {
valOff = mpSkipOne(a, n, iCur); /* non-string key */
}
valOff = mpSkipOne(a, n, iCur);
if( !valOff ) return SQLITE_ERROR;
if( !valOff || valOff > n ) return SQLITE_ERROR;
if( kStr && (int)kLen==nKey && memcmp(kStr,zKey,(size_t)nKey)==0 ){
iCur = valOff;
found = 1;
Expand Down
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