FastRandom

FastRandom is a high-performance, thread-safe random number generator using the Xorshift128 algorithm. It is significantly faster than System.Random and provides per-thread instances to avoid contention in multi-threaded scenarios.

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Overview

Feature	Description
Algorithm	Xorshift128
Performance	Significantly faster than System.Random
Thread Safety	Thread-local instances via Shared
Deterministic	Seeded instances produce reproducible sequences
Distribution	Uniform distribution for all methods

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Properties

Property	Description
Shared	Gets a thread-local FastRandom instance for the current thread

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Constructors

// Create with a seed for deterministic sequences
var random = new FastRandom(12345);
int value = random.Next(); // Always produces the same sequence

// Create with a seed derived from system time (default)
var random2 = new FastRandom();

// Use the shared thread-local instance
var shared = FastRandom.Shared;

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Methods

Next

Generates a random non-negative integer.

var random = FastRandom.Shared;

// Random integer between 0 and int.MaxValue - 1
int value = random.Next();

Next(maxValue)

Generates a random integer between 0 (inclusive) and the specified maximum (exclusive).

// Random integer between 0 and 99
int value = random.Next(100);

Next(minValue, maxValue)

Generates a random integer between the specified minimum (inclusive) and maximum (exclusive).

// Random integer between 10 and 99
int value = random.Next(10, 100);

NextBoolean

Generates a random boolean value.

bool value = random.NextBoolean();  // true or false

NextFloat

Generates a random float between 0 (inclusive) and 1 (exclusive).

float value = random.NextFloat();  // 0.0 to 1.0

NextFloat(maxValue)

Generates a random float between 0 (inclusive) and the specified maximum (exclusive).

float value = random.NextFloat(100f);  // 0.0 to 100.0

NextFloat(minValue, maxValue)

Generates a random float between the specified minimum (inclusive) and maximum (exclusive).

float value = random.NextFloat(10f, 100f);

NextDouble

Generates a random double between 0 (inclusive) and 1 (exclusive).

double value = random.NextDouble();  // 0.0 to 1.0

NextDouble(maxValue)

Generates a random double between 0 (inclusive) and the specified maximum (exclusive).

double value = random.NextDouble(100.0);

NextDouble(minValue, maxValue)

Generates a random double between the specified minimum (inclusive) and maximum (exclusive).

double value = random.NextDouble(10.0, 100.0);

RangeInt

Generates a random integer between the specified minimum (inclusive) and maximum (inclusive).

// Random integer between 10 and 100 inclusive
int value = random.RangeInt(10, 100);

RangeFloat

Generates a random float between the specified minimum (inclusive) and maximum (inclusive).

float value = random.RangeFloat(10f, 100f);

RangeDouble

Generates a random double between the specified minimum (inclusive) and maximum (inclusive).

double value = random.RangeDouble(10.0, 100.0);

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Examples

Basic Usage

var random = FastRandom.Shared;

int diceRoll = random.RangeInt(1, 6);
float health = random.NextFloat(50f, 100f);
bool criticalHit = random.NextBoolean();

Deterministic Sequences

// Seeded random for reproducible results
var random1 = new FastRandom(42);
var random2 = new FastRandom(42);

int a = random1.Next();  // Same value
int b = random2.Next();  // Same value

// Useful for testing and procedural generation

Thread Safety

// Each thread gets its own instance automatically
var random = FastRandom.Shared;  // Thread-local

// No locks required, no contention
Parallel.For(0, 100, i =>
{
    int value = FastRandom.Shared.Next(100);
    // Process value
});

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Performance

Method	Performance
Next()	Fast
Next(max)	Fast
NextFloat()	Fast
NextDouble()	Fast
NextBoolean()	Fast

FastRandom is significantly faster than System.Random and uses no locks when accessed through the Shared property.

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Summary

Feature	Support
Xorshift128 algorithm	✅
Thread-local instances	✅
Deterministic seeding	✅
Integer generation	✅
Float generation	✅
Double generation	✅
Boolean generation	✅
Inclusive ranges	✅
Exclusive ranges	✅

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