bloom-filter.hpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2014-2020,  The University of Memphis
 *
 * This file is part of PSync.
 * See AUTHORS.md for complete list of PSync authors and contributors.
 *
 * PSync is free software: you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation,
 * either version 3 of the License, or (at your option) any later version.
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 * You should have received a copy of the GNU Lesser General Public License along with
 * PSync, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
 *

 * This file incorporates work covered by the following copyright and
 * permission notice:

 * The MIT License (MIT)

 * Copyright (c) 2000 Arash Partow

 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
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*/

#ifndef PSYNC_DETAIL_BLOOM_FILTER_HPP
#define PSYNC_DETAIL_BLOOM_FILTER_HPP

#include <ndn-cxx/name.hpp>
#include <ndn-cxx/util/string-helper.hpp>

#include <string>
#include <vector>

namespace psync {
namespace detail {

class bloom_parameters;

class BloomFilter
{
public:
  class Error : public std::runtime_error
  {
  public:
    using std::runtime_error::runtime_error;
  };

  BloomFilter() = default;

  BloomFilter(unsigned int projected_element_count,
              double false_positive_probability);

  BloomFilter(unsigned int projected_element_count,
              double false_positive_probability,
              const ndn::name::Component& bfName);

  void
  appendToName(ndn::Name& name) const;

  void
  clear();

  void
  insert(const std::string& key);

  bool
  contains(const std::string& key) const;

private:
  typedef uint32_t bloom_type;
  typedef uint8_t cell_type;

  explicit
  BloomFilter(const bloom_parameters& p);

  void
  compute_indices(const bloom_type& hash, std::size_t& bit_index, std::size_t& bit) const;

  void
  generate_unique_salt();

private: // non-member operators
  // NOTE: the following "hidden friend" operators are available via
  //       argument-dependent lookup only and must be defined inline.

  friend bool
  operator==(const BloomFilter& lhs, const BloomFilter& rhs)
  {
    return lhs.bit_table_ == rhs.bit_table_;
  }

  friend bool
  operator!=(const BloomFilter& lhs, const BloomFilter& rhs)
  {
    return lhs.bit_table_ != rhs.bit_table_;
  }

  friend std::ostream&
  operator<<(std::ostream& os, const BloomFilter& bf)
  {
    ndn::printHex(os, bf.bit_table_.data(), bf.bit_table_.size(), false);
    return os;
  }

private:
  std::vector<bloom_type> salt_;
  std::vector<cell_type>  bit_table_;
  unsigned int            salt_count_ = 0;
  unsigned int            table_size_ = 0;
  unsigned int            projected_element_count_ = 0;
  unsigned int            inserted_element_count_ = 0;
  unsigned long long int  random_seed_ = 0;
  double                  desired_false_positive_probability_ = 0.0;
};

} // namespace detail
} // namespace psync

#endif // PSYNC_DETAIL_BLOOM_FILTER_HPP