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hllSparseAdd(): speed optimization.

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Mostly by reordering opcodes check conditional by frequency of opcodes
in larger sparse-encoded HLLs.
This commit is contained in:
antirez 2014-04-14 15:42:05 +02:00
parent 681bf7468b
commit e9cd51c7eb
1 changed files with 14 additions and 11 deletions
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25
src/hyperloglog.c
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@ -440,7 +440,7 @@ uint64_t MurmurHash64A (const void * key, int len, unsigned int seed) {
/* Given a string element to add to the HyperLogLog, returns the length
* of the pattern 000..1 of the element hash. As a side effect 'regp' is
* set to the register index this element hashes to. */
int hllPatLen(unsigned char *ele, size_t elesize, int *regp) {
int hllPatLen(unsigned char *ele, size_t elesize, long *regp) {
uint64_t hash, bit, index;
int count;
@ -483,7 +483,7 @@ int hllPatLen(unsigned char *ele, size_t elesize, int *regp) {
* is returned. */
int hllDenseAdd(uint8_t *registers, unsigned char *ele, size_t elesize) {
uint8_t oldcount, count;
int index;
long index;
/* Update the register if this element produced a longer run of zeroes. */
count = hllPatLen(ele,elesize,&index);
@ -636,8 +636,8 @@ int hllSparseToDense(robj *o) {
int hllSparseAdd(robj *o, unsigned char *ele, size_t elesize) {
struct hllhdr *hdr;
uint8_t oldcount, count, *sparse, *end, *p, *prev, *next;
int index, first, span;
int is_zero = 0, is_xzero = 0, is_val = 0, runlen = 0;
long index, first, span;
long is_zero = 0, is_xzero = 0, is_val = 0, runlen = 0;
/* Update the register if this element produced a longer run of zeroes. */
count = hllPatLen(ele,elesize,&index);
@ -663,18 +663,21 @@ int hllSparseAdd(robj *o, unsigned char *ele, size_t elesize) {
next = NULL; /* Points to the next opcode at the end of the loop. */
span = 0;
while(p < end) {
int oplen;
long oplen;
/* Set span to the number of registers covered by this opcode. */
/* Set span to the number of registers covered by this opcode.
*
* This is the most performance critical loop of the sparse
* representation. Sorting the conditionals from the most to the
* least frequent opcode in many-bytes sparse HLLs is faster. */
oplen = 1;
if (HLL_SPARSE_IS_ZERO(p)) {
span = HLL_SPARSE_ZERO_LEN(p);
oplen = 1;
} else if (HLL_SPARSE_IS_XZERO(p)) {
} else if (HLL_SPARSE_IS_VAL(p)) {
span = HLL_SPARSE_VAL_LEN(p);
} else { /* XZERO. */
span = HLL_SPARSE_XZERO_LEN(p);
oplen = 2;
} else {
span = HLL_SPARSE_VAL_LEN(p);
oplen = 1;
}
/* Break if this opcode covers the register as 'index'. */
if (index <= first+span-1) break;