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fix(rowstorage): SplitMix64 PRNG implementation to replace stdlib MT PRNG that uses /dev/urandom guarded by spinlock

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This commit is contained in:
Roman Nozdrin
2023-11-01 18:19:34 +00:00
parent 7aa6e4c107
commit dfc9e89496
2 changed files with 18 additions and 8 deletions
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19
utils/rowgroup/rowstorage.h
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@ -311,6 +311,21 @@ class RowAggStorage
static constexpr uint8_t INIT_INFO_HASH_SHIFT{0};
static constexpr uint16_t MAX_INMEMORY_GENS{4};
// This is SplitMix64 implementation borrowed from here
// https://thompsonsed.co.uk/random-number-generators-for-c-performance-tested
inline uint64_t nextRandom()
{
uint64_t z = (fRandom += UINT64_C(0x9E3779B97F4A7C15));
z = (z ^ (z >> 30)) * UINT64_C(0xBF58476D1CE4E5B9);
z = (z ^ (z >> 27)) * UINT64_C(0x94D049BB133111EB);
return z ^ (z >> 31);
}
inline uint64_t nextRandDistib()
{
return nextRandom() % 100;
}
struct Data
{
RowPosHashStoragePtr fHashes;
@ -349,9 +364,7 @@ class RowAggStorage
bool fInitialized{false};
rowgroup::RowGroup* fRowGroupOut;
rowgroup::RowGroup* fKeysRowGroup;
std::random_device fRD;
std::mt19937 fRandGen;
std::uniform_int_distribution<uint8_t> fRandDistr;
uint64_t fRandom = 0xc4ceb9fe1a85ec53ULL; // initial integer to set PRNG up
};
} // namespace rowgroup