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Strange optimizations for 64 bit integers.

This commit is contained in:
Davi Reis 2012-03-13 20:25:06 -03:00
parent 7b8b3e5834
commit aa5fa26b49
2 changed files with 33 additions and 3 deletions
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2
cxxmph/bm_map.cc
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@ -88,12 +88,14 @@ using namespace cxxmph;
int main(int argc, char** argv) {
srandom(4);
/*
Benchmark::Register(new BM_CreateUrls<mph_map<StringPiece, StringPiece>>("URLS100k"));
Benchmark::Register(new BM_CreateUrls<unordered_map<StringPiece, StringPiece>>("URLS100k"));
Benchmark::Register(new BM_SearchUrls<mph_map<StringPiece, StringPiece>>("URLS100k", 10*1000 * 1000, 0));
Benchmark::Register(new BM_SearchUrls<unordered_map<StringPiece, StringPiece, Murmur3StringPiece>>("URLS100k", 10*1000 * 1000, 0));
Benchmark::Register(new BM_SearchUrls<mph_map<StringPiece, StringPiece>>("URLS100k", 10*1000 * 1000, 0.9));
Benchmark::Register(new BM_SearchUrls<unordered_map<StringPiece, StringPiece, Murmur3StringPiece>>("URLS100k", 10*1000 * 1000, 0.9));
*/
Benchmark::Register(new BM_SearchUint64<unordered_map<uint64_t, uint64_t>>);
Benchmark::Register(new BM_SearchUint64<mph_map<uint64_t, uint64_t>>);
Benchmark::RunAll();

34
cxxmph/seeded_hash.h
View File

@ -9,8 +9,9 @@
#include "MurmurHash3.h"
#include "stringpiece.h"
// From murmur, only used naively to extend 32 bits functions to 64 bits.
// From murmur, only used naively to extend 32 bits functions to 128 bits.
uint32_t fmix ( uint32_t h );
uint64_t fmix ( uint64_t h );
namespace cxxmph {
@ -57,6 +58,19 @@ struct Murmur3StringPiece {
}
};
struct Murmur3Fmix64bitsType {
template <class Key>
uint32_t operator()(const Key& k) const {
return fmix(*reinterpret_cast<const uint64_t*>(&k));
}
template <class Key>
void hash64(const Key& k, uint32_t* out) const {
uint64_t h = fmix(*reinterpret_cast<uint64_t*>(&k));
*reinterpret_cast<uint64_t*>(out) = h;
*reinterpret_cast<uint64_t*>(out + 2) = h;
}
};
template <>
struct seeded_hash_function<Murmur3> {
template <class Key>
@ -87,6 +101,20 @@ struct seeded_hash_function<Murmur3StringPiece> {
}
};
template <>
struct seeded_hash_function<Murmur3Fmix64bitsType> {
template <class Key>
uint32_t operator()(const Key& k, uint32_t seed) const {
return fmix(k + seed);
}
template <class Key>
void hash64(const Key& k, uint32_t seed, uint32_t* out) const {
*reinterpret_cast<uint64_t*>(out) = fmix(k ^ seed);
*(out + 2) = fmix(*out);
}
};
template <class HashFcn> struct seeded_hash
{ typedef seeded_hash_function<HashFcn> hash_function; };
// Use Murmur3 instead for all types defined in std::hash, plus
@ -117,9 +145,9 @@ template <> struct seeded_hash<std::hash<long> >
template <> struct seeded_hash<std::hash<unsigned long> >
{ typedef seeded_hash_function<Murmur3> hash_function; };
template <> struct seeded_hash<std::hash<long long> >
{ typedef seeded_hash_function<Murmur3> hash_function; };
{ typedef seeded_hash_function<Murmur3Fmix64bitsType> hash_function; };
template <> struct seeded_hash<std::hash<unsigned long long> >
{ typedef seeded_hash_function<Murmur3> hash_function; };
{ typedef seeded_hash_function<Murmur3Fmix64bitsType> hash_function; };
} // namespace cxxmph