ceph/src/common/rabin.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Authors : Yuan-Ting Hsieh, Hsuan-Heng Wu, Myoungwon Oh
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #ifndef CEPH_COMMON_RABIN_H_
  16 #define CEPH_COMMON_RABIN_H_
  17
  18 class RabinChunk {
  19 public:
  20   RabinChunk(uint32_t window_size, uint32_t rabin_prime,
  21              uint64_t mod_prime, uint64_t pow, vector<uint64_t> rabin_mask, uint64_t min,
  22              uint64_t max, uint32_t num_bits):
  23               window_size(window_size), rabin_prime(rabin_prime), mod_prime(mod_prime),
  24               pow(pow), rabin_mask(rabin_mask), min(min), max(max), num_bits(num_bits) {}
  25   RabinChunk() {
  26     default_init_rabin_options();
  27   }
  28
  29   void default_init_rabin_options() {
  30     vector<uint64_t> _rabin_mask = {0,1,3,7,15,31,63,127,255,511,1023,2047,4095,8191,16383,32767,65535};
  31     window_size = 48;
  32     rabin_prime = 3;
  33     mod_prime = 6148914691236517051;
  34     pow = 907234050803559263; // pow(prime, window_size)
  35     min = 8000;
  36     max = 16000;
  37     num_bits = 3;
  38     rabin_mask = _rabin_mask;
  39   }
  40
  41   int do_rabin_chunks(bufferlist & inputdata,
  42                       vector<pair<uint64_t, uint64_t>> & chunks,
  43                       uint64_t min, uint64_t max);
  44   uint64_t gen_rabin_hash(char* chunk_data, uint64_t off, uint64_t len = 0);
  45   bool end_of_chunk(const uint64_t fp , int numbits);
  46   void set_window_size(uint32_t size) { window_size = size; }
  47   void set_rabin_prime(uint32_t r_prime) { rabin_prime = r_prime; }
  48   void set_mod_prime(uint64_t m_prime) { mod_prime = m_prime; }
  49   void set_pow(uint64_t p) { pow = p; }
  50   void set_rabin_mask(vector<uint64_t> & mask) { rabin_mask = mask; }
  51   void set_min_chunk(uint32_t c_min) { min = c_min; }
  52   void set_max_chunk(uint32_t c_max) { max = c_max; }
  53   int add_rabin_mask(uint64_t mask) {
  54     rabin_mask.push_back(mask);
  55     for (int i = 0; rabin_mask.size(); i++) {
  56       if (rabin_mask[i] == mask) {
  57         return i;
  58       }
  59     }
  60     return -1;
  61   }
  62   void set_numbits(uint32_t bit) { num_bits = bit; }
  63
  64 private:
  65
  66   uint32_t window_size;
  67   uint32_t rabin_prime;
  68   uint64_t mod_prime;
  69   uint64_t pow;
  70   vector<uint64_t> rabin_mask;
  71   uint64_t min;
  72   uint64_t max;
  73   uint32_t num_bits;
  74 };
  75
  76
  77 #endif // CEPH_COMMON_RABIN_H_