RandomMixin< T > Class Template Reference

Mixin class that provides helper randomness functions. More...

#include <random.h>

Public Types
typedef uint64_t	result_type

Public Member Functions
constexpr	RandomMixin () noexcept=default
	RandomMixin (const RandomMixin &)=delete
RandomMixin &	operator= (const RandomMixin &)=delete
	RandomMixin (RandomMixin &&)=delete
RandomMixin &	operator= (RandomMixin &&)=delete
uint64_t	randbits (int bits) noexcept
	Generate a random (bits)-bit integer.
template<int Bits>
uint64_t	randbits () noexcept
	Same as above, but with compile-time fixed bits count.
template<std::integral I>
I	randrange (I range) noexcept
	Generate a random integer in the range [0..range), with range > 0.
void	fillrand (std::span< std::byte > span) noexcept
	Fill a span with random bytes.
template<std::integral I>
I	rand () noexcept
	Generate a random integer in its entire (non-negative) range.
template<BasicByte B = unsigned char>
std::vector< B >	randbytes (size_t len) noexcept
	Generate random bytes.
template<size_t N, BasicByte B = std::byte>
std::array< B, N >	randbytes () noexcept
	Generate fixed-size random bytes.
uint32_t	rand32 () noexcept
	Generate a random 32-bit integer.
uint256	rand256 () noexcept
	generate a random uint256.
bool	randbool () noexcept
	Generate a random boolean.
template<typename Tp>
Tp	rand_uniform_delay (const Tp &time, typename Tp::duration range) noexcept
	Return the time point advanced by a uniform random duration.
template<typename Chrono>
Chrono::duration	rand_uniform_duration (typename Chrono::duration range) noexcept
	Generate a uniform random duration in the range from 0 (inclusive) to range (exclusive).
template<StdChronoDuration Dur>
Dur	randrange (std::common_type_t< Dur > range) noexcept
	Generate a uniform random duration in the range [0..max).
std::chrono::microseconds	rand_exp_duration (std::chrono::microseconds mean) noexcept
	Return a duration sampled from an exponential distribution (https://en.wikipedia.org/wiki/Exponential_distribution).
uint64_t	operator() () noexcept

Static Public Member Functions
static constexpr uint64_t	min () noexcept
static constexpr uint64_t	max () noexcept

Protected Member Functions
constexpr void	FlushCache () noexcept

Private Member Functions
RandomNumberGenerator auto &	Impl () noexcept
	Access the underlying generator.

Private Attributes
uint64_t	bitbuf {0}
int	bitbuf_size {0}

Detailed Description

template<typename T>
class RandomMixin< T >

Mixin class that provides helper randomness functions.

Intended to be used through CRTP: https://en.cppreference.com/w/cpp/language/crtp. An RNG class FunkyRNG would derive publicly from RandomMixin<FunkyRNG>. This permits RandomMixin from accessing the derived class's rand64() function, while also allowing the derived class to provide more.

The derived class must satisfy the RandomNumberGenerator concept.

Definition at line 174 of file random.h.

Member Typedef Documentation

result_type

template<typename T>

typedef uint64_t RandomMixin< T >::result_type

Definition at line 373 of file random.h.

Constructor & Destructor Documentation

RandomMixin() [1/3]

template<typename T>

RandomMixin< T >::RandomMixin ( )

constexprdefaultnoexcept

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RandomMixin() [2/3]

template<typename T>

RandomMixin< T >::RandomMixin ( const RandomMixin< T > & )

delete

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RandomMixin() [3/3]

template<typename T>

RandomMixin< T >::RandomMixin ( RandomMixin< T > && )

delete

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Member Function Documentation

fillrand()

template<typename T>

void RandomMixin< T >::fillrand ( std::span< std::byte > span )

inlinenoexcept

Fill a span with random bytes.

Definition at line 267 of file random.h.

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FlushCache()

template<typename T>

void RandomMixin< T >::FlushCache ( )

inlineconstexprprotectednoexcept

Definition at line 188 of file random.h.

Impl()

template<typename T>

RandomNumberGenerator auto & RandomMixin< T >::Impl ( )

inlineprivatenoexcept

Access the underlying generator.

This also enforces the RandomNumberGenerator concept. We cannot declare that in the template (no template<RandomNumberGenerator T>) because the type isn't fully instantiated yet there.

Definition at line 185 of file random.h.

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max()

template<typename T>

constexpr uint64_t RandomMixin< T >::max ( )

inlinestaticconstexprnoexcept

Definition at line 375 of file random.h.

min()

template<typename T>

constexpr uint64_t RandomMixin< T >::min ( )

inlinestaticconstexprnoexcept

Definition at line 374 of file random.h.

operator()()

template<typename T>

uint64_t RandomMixin< T >::operator() ( )

inlinenoexcept

Definition at line 376 of file random.h.

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operator=() [1/2]

template<typename T>

RandomMixin & RandomMixin< T >::operator= ( const RandomMixin< T > & )

delete

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operator=() [2/2]

template<typename T>

RandomMixin & RandomMixin< T >::operator= ( RandomMixin< T > && )

delete

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rand()

template<typename T>

template<std::integral I>

I RandomMixin< T >::rand ( )

inlinenoexcept

Generate a random integer in its entire (non-negative) range.

Definition at line 287 of file random.h.

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rand256()

template<typename T>

uint256 RandomMixin< T >::rand256 ( )

inlinenoexcept

generate a random uint256.

Definition at line 317 of file random.h.

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rand32()

template<typename T>

uint32_t RandomMixin< T >::rand32 ( )

inlinenoexcept

Generate a random 32-bit integer.

Definition at line 314 of file random.h.

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rand_exp_duration()

template<typename T>

std::chrono::microseconds RandomMixin< T >::rand_exp_duration ( std::chrono::microseconds mean )

inlinenoexcept

Return a duration sampled from an exponential distribution (https://en.wikipedia.org/wiki/Exponential_distribution).

Successive events whose intervals are distributed according to this form a memoryless Poisson process. This should be used for repeated network events (e.g. sending a certain type of message) to minimize leaking information to observers.

The probability of an event occurring before time x is 1 - e^-(x/a) where a is the average interval between events.

Definition at line 365 of file random.h.

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rand_uniform_delay()

template<typename T>

template<typename Tp>

Tp RandomMixin< T >::rand_uniform_delay ( const Tp & time, typename Tp::duration range )

inlinenoexcept

Return the time point advanced by a uniform random duration.

Definition at line 329 of file random.h.

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rand_uniform_duration()

template<typename T>

template<typename Chrono>

Chrono::duration RandomMixin< T >::rand_uniform_duration ( typename Chrono::duration range )

inlinenoexcept

Generate a uniform random duration in the range from 0 (inclusive) to range (exclusive).

Definition at line 336 of file random.h.

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randbits() [1/2]

template<typename T>

template<int Bits>

uint64_t RandomMixin< T >::randbits ( )

inlinenoexcept

Same as above, but with compile-time fixed bits count.

Definition at line 230 of file random.h.

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randbits() [2/2]

template<typename T>

uint64_t RandomMixin< T >::randbits ( int bits )

inlinenoexcept

Generate a random (bits)-bit integer.

Definition at line 204 of file random.h.

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randbool()

template<typename T>

bool RandomMixin< T >::randbool ( )

inlinenoexcept

Generate a random boolean.

Definition at line 325 of file random.h.

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randbytes() [1/2]

template<typename T>

template<size_t N, BasicByte B = std::byte>

std::array< B, N > RandomMixin< T >::randbytes ( )

inlinenoexcept

Generate fixed-size random bytes.

Definition at line 306 of file random.h.

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randbytes() [2/2]

template<typename T>

template<BasicByte B = unsigned char>

std::vector< B > RandomMixin< T >::randbytes ( size_t len )

inlinenoexcept

Generate random bytes.

Definition at line 297 of file random.h.

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randrange() [1/2]

template<typename T>

template<std::integral I>

I RandomMixin< T >::randrange ( I range )

inlinenoexcept

Generate a random integer in the range [0..range), with range > 0.

Definition at line 254 of file random.h.

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randrange() [2/2]

template<typename T>

template<StdChronoDuration Dur>

Dur RandomMixin< T >::randrange ( std::common_type_t< Dur > range )

inlinenoexcept

Generate a uniform random duration in the range [0..max).

Precondition: max.count() > 0

Definition at line 346 of file random.h.

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Member Data Documentation

bitbuf

template<typename T>

uint64_t RandomMixin< T >::bitbuf {0}

private

Definition at line 177 of file random.h.

bitbuf_size

template<typename T>

int RandomMixin< T >::bitbuf_size {0}

private

Definition at line 178 of file random.h.

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

• src/random.h