git.m6w6.name Git - m6w6/libmemcached/blob - src/bin/common/random.hpp

   1 /*
   2     +--------------------------------------------------------------------+
   3     | libmemcached - C/C++ Client Library for memcached                  |
   4     +--------------------------------------------------------------------+
   5     | Redistribution and use in source and binary forms, with or without |
   6     | modification, are permitted under the terms of the BSD license.    |
   7     | You should have received a copy of the license in a bundled file   |
   8     | named LICENSE; in case you did not receive a copy you can review   |
   9     | the terms online at: https://opensource.org/licenses/BSD-3-Clause  |
  10     +--------------------------------------------------------------------+
  11     | Copyright (c) 2006-2014 Brian Aker   https://datadifferential.com/ |
  12     | Copyright (c) 2020 Michael Wallner   <mike@php.net>                |
  13     +--------------------------------------------------------------------+
  14 */
  15
  16 #pragma once
  17
  18 #include "time.hpp"
  19 #include <random>
  20
  21 class random64 {
  22 public:
  23   using typ = std::mt19937_64::result_type;
  24
  25   random64()
  26   : gen{static_cast<typ>(time_clock::now().time_since_epoch().count())}
  27   , dst{}
  28   {}
  29
  30   typ operator()(typ min = 0, typ max = std::numeric_limits<typ>::max()) {
  31     return (dst(gen) % (max - min)) + min;
  32   }
  33
  34   void fill(char *buf, size_t len,
  35       const std::string &set = "0123456789ABCDEFGHIJKLMNOPQRSTWXYZabcdefghijklmnopqrstuvwxyz") {
  36     for (auto i = 0ul; i < len; ++i) {
  37       buf[i] = set[(*this)(0, set.length()-1)];
  38     }
  39   }
  40
  41 private:
  42   std::mt19937_64 gen;
  43   std::uniform_int_distribution<typ> dst;
  44 };