foedus::assorted::ZipfianRandom Class Reference

A simple zipfian generator based off of YCSB's Java implementation. More...

Detailed Description

A simple zipfian generator based off of YCSB's Java implementation.

The major user is YCSB. 0 <= theta < 1, higher means more skewed. Generates a random number between 0 and max_.

Definition at line 37 of file zipfian_random.hpp.

#include <zipfian_random.hpp>

Public Member Functions
void	init (uint64_t items, double theta, uint64_t urnd_seed)
	ZipfianRandom (uint64_t items, double theta, uint64_t urnd_seed)
	ZipfianRandom ()
uint64_t	next ()
uint64_t	get_current_seed () const
void	set_current_seed (uint64_t seed)

Constructor & Destructor Documentation

foedus::assorted::ZipfianRandom::ZipfianRandom ( uint64_t  items, double  theta, uint64_t  urnd_seed  )

inline

Definition at line 57 of file zipfian_random.hpp.

References init().

                                                                  {
    init(items, theta, urnd_seed);
  }

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foedus::assorted::ZipfianRandom::ZipfianRandom ( )

inline

Definition at line 61 of file zipfian_random.hpp.

{}

Member Function Documentation

uint64_t foedus::assorted::ZipfianRandom::get_current_seed ( ) const

inline

Definition at line 78 of file zipfian_random.hpp.

References foedus::assorted::UniformRandom::get_current_seed().

{ return urnd_.get_current_seed(); }

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void foedus::assorted::ZipfianRandom::init ( uint64_t  items, double  theta, uint64_t  urnd_seed  )

inline

Definition at line 48 of file zipfian_random.hpp.

References foedus::assorted::UniformRandom::set_current_seed().

Referenced by ZipfianRandom().

                                                              {
    max_ = items - 1;
    theta_ = theta;
    zetan_ = zeta(items);
    alpha_ = 1.0 / (1.0 - theta_);
    eta_ = (1 - std::pow(2.0 / items, 1 - theta_)) / (1 - zeta(2) / zetan_);
    urnd_.set_current_seed(urnd_seed);
  }

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uint64_t foedus::assorted::ZipfianRandom::next ( )

inline

Definition at line 63 of file zipfian_random.hpp.

References foedus::assorted::UniformRandom::uniform_within().

                  {
    double u = urnd_.uniform_within(0, max_) / static_cast<double>(max_);
    double uz = u * zetan_;
    if (uz < 1.0) {
      return 0;
    }

    if (uz < 1.0 + std::pow(0.5, theta_)) {
      return 1;
    }

    uint64_t ret = static_cast<uint64_t>(max_ * std::pow(eta_ * u - eta_ + 1, alpha_));
    return ret;
  }

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void foedus::assorted::ZipfianRandom::set_current_seed ( uint64_t  seed )

inline

Definition at line 79 of file zipfian_random.hpp.

References foedus::assorted::UniformRandom::set_current_seed().

{ urnd_.set_current_seed(seed); }

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The documentation for this class was generated from the following file:

• /home/shino/foedus_code/foedus-core/include/foedus/assorted/zipfian_random.hpp