FastRandomContext Class Reference

Fast randomness source. More...

#include <random.h>

Inheritance diagram for FastRandomContext:

Collaboration diagram for FastRandomContext:

Public Member Functions
	FastRandomContext (bool fDeterministic=false) noexcept
	Construct a FastRandomContext with GetRandHash()-based entropy (or zero key if fDeterministic).
	FastRandomContext (const uint256 &seed) noexcept
	Initialize with explicit seed (only for testing).
void	Reseed (const uint256 &seed) noexcept
	Reseed with explicit seed (only for testing).
uint64_t	rand64 () noexcept
	Generate a random 64-bit integer.
void	fillrand (std::span< std::byte > output) noexcept
	Fill a byte span with random bytes.
Public Member Functions inherited from RandomMixin< FastRandomContext >
constexpr	RandomMixin () noexcept=default
RandomMixin &	operator= (const RandomMixin &)=delete
uint64_t	randbits (int bits) noexcept
	Generate a random (bits)-bit integer.
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.
I	rand () noexcept
	Generate a random integer in its entire (non-negative) range.
std::vector< B >	randbytes (size_t len) noexcept
	Generate 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.
Tp	rand_uniform_delay (const Tp &time, typename Tp::duration range) noexcept
	Return the time point advanced by a uniform random duration.
Chrono::duration	rand_uniform_duration (typename Chrono::duration range) noexcept
	Generate a uniform random duration in the range from 0 (inclusive) to range (exclusive).
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

Private Member Functions
void	RandomSeed () noexcept

Private Attributes
bool	requires_seed
ChaCha20	rng

Additional Inherited Members
Public Types inherited from RandomMixin< FastRandomContext >
typedef uint64_t	result_type
Static Public Member Functions inherited from RandomMixin< FastRandomContext >
static constexpr uint64_t	min () noexcept
static constexpr uint64_t	max () noexcept
Protected Member Functions inherited from RandomMixin< FastRandomContext >
constexpr void	FlushCache () noexcept

Detailed Description

Fast randomness source.

This is seeded once with secure random data, but is completely deterministic and does not gather more entropy after that.

This class is not thread-safe.

Definition at line 385 of file random.h.

Constructor & Destructor Documentation

FastRandomContext() [1/2]

FastRandomContext::FastRandomContext ( bool fDeterministic = false )

explicitnoexcept

Construct a FastRandomContext with GetRandHash()-based entropy (or zero key if fDeterministic).

Definition at line 689 of file random.cpp.

FastRandomContext() [2/2]

FastRandomContext::FastRandomContext ( const uint256 & seed )

explicitnoexcept

Initialize with explicit seed (only for testing).

Definition at line 632 of file random.cpp.

Member Function Documentation

fillrand()

void FastRandomContext::fillrand ( std::span< std::byte > output )

noexcept

Fill a byte span with random bytes.

This overrides the RandomMixin version.

Definition at line 626 of file random.cpp.

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rand64()

uint64_t FastRandomContext::rand64 ( )

inlinenoexcept

Generate a random 64-bit integer.

Definition at line 404 of file random.h.

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RandomSeed()

void FastRandomContext::RandomSeed ( )

privatenoexcept

Definition at line 619 of file random.cpp.

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Reseed()

void FastRandomContext::Reseed ( const uint256 & seed )

noexcept

Reseed with explicit seed (only for testing).

Definition at line 634 of file random.cpp.

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Member Data Documentation

requires_seed

bool FastRandomContext::requires_seed

private

Definition at line 388 of file random.h.

rng

ChaCha20 FastRandomContext::rng

private

Definition at line 389 of file random.h.

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

• src/random.h
• src/random.cpp