YugabyteDB (2.13.1.0-b60, 21121d69985fbf76aa6958d8f04a9bfa936293b5)

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#include <stdint.h>

#ifndef YB_UTIL_HASH_UTIL_H

#define YB_UTIL_HASH_UTIL_H

namespace yb {

/// Utility class to compute hash values.

class HashUtil {

 public:

  static const uint64_t MURMUR_PRIME = 0xc6a4a7935bd1e995;

  static const int MURMUR_R = 47;

  /// Murmur2 hash implementation returning 64-bit hashes.

  static uint64_t MurmurHash2_64(const void* input, size_t len, uint64_t seed) {

    uint64_t h = seed ^ (len * MURMUR_PRIME);

    const uint64_t* data = reinterpret_cast<const uint64_t*>(input);

    const uint64_t* end = data + (len / sizeof(uint64_t));

    while (data != end) {

      uint64_t k = *data++;

      k *= MURMUR_PRIME;

      k ^= k >> MURMUR_R;

      k *= MURMUR_PRIME;

      h ^= k;

      h *= MURMUR_PRIME;

    }

    const uint8_t* data2 = reinterpret_cast<const uint8_t*>(data);

    switch (len & 7) {

      case 7: h ^= static_cast<uint64_t>(data2[6]) << 48; FALLTHROUGH_INTENDED;

      case 6: h ^= static_cast<uint64_t>(data2[5]) << 40; FALLTHROUGH_INTENDED;

      case 5: h ^= static_cast<uint64_t>(data2[4]) << 32; FALLTHROUGH_INTENDED;

      case 4: h ^= static_cast<uint64_t>(data2[3]) << 24; FALLTHROUGH_INTENDED;

      case 3: h ^= static_cast<uint64_t>(data2[2]) << 16; FALLTHROUGH_INTENDED;

      case 2: h ^= static_cast<uint64_t>(data2[1]) << 8; FALLTHROUGH_INTENDED;

      case 1: h ^= static_cast<uint64_t>(data2[0]);

              h *= MURMUR_PRIME;

    }

    h ^= h >> MURMUR_R;

    h *= MURMUR_PRIME;

    h ^= h >> MURMUR_R;

    return h;

  }

};

} // namespace yb

#endif // YB_UTIL_HASH_UTIL_H