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 #undef max
  21
  22 class random64 {
  23 public:
  24   using typ = std::mt19937_64::result_type;
  25
  26   random64()
  27   : gen{static_cast<typ>(time_clock::now().time_since_epoch().count())}
  28   , dst{}
  29   {}
  30
  31   typ operator()(typ min_ = 0, typ max_ = std::numeric_limits<typ>::max()) {
  32     return (dst(gen) % (max_ - min_)) + min_;
  33   }
  34
  35   void fill(char *buf, size_t len,
  36       const std::string &set = "0123456789ABCDEFGHIJKLMNOPQRSTWXYZabcdefghijklmnopqrstuvwxyz") {
  37     for (auto i = 0ul; i < len; ++i) {
  38       buf[i] = set[(*this)(0, set.length()-1)];
  39     }
  40   }
  41
  42 private:
  43   std::mt19937_64 gen;
  44   std::uniform_int_distribution<typ> dst;
  45 };