smhasher

SMHasher is a test suite designed to test the quality of hash functions. It provides a comprehensive set of tests to evaluate various properties of hash functions, including distribution, avalanche, and collision resistance. The project aims to help developers choose appropriate hash functions for their specific use cases and to assist in the development of new hash functions.

Pros

• Comprehensive test suite for evaluating hash functions
• Supports a wide range of hash functions, including popular ones like MurmurHash and CityHash
• Provides detailed statistical analysis and visualizations of test results
• Open-source and actively maintained

Cons

• Primarily focused on non-cryptographic hash functions
• Can be complex to set up and use for beginners
• Limited documentation for some advanced features
• May require significant computational resources for thorough testing of complex hash functions

Code Examples

1. Testing a custom hash function:

#include "SMHasher.h"

uint32_t MyCustomHash(const void* key, int len, uint32_t seed) {
    // Your hash function implementation here
}

int main(int argc, char** argv) {
    HashInfo hi;
    hi.hash = MyCustomHash;
    hi.name = "MyCustomHash";
    
    TestHashFunction(hi);
    return 0;
}

2. Running specific tests on a hash function:

#include "SMHasher.h"

int main(int argc, char** argv) {
    HashInfo hi;
    hi.hash = MurmurHash3_x86_32;
    hi.name = "MurmurHash3_x86_32";
    
    Test<Blob>("Bit Independence Criteria", 100000, 300, hi.hash, true);
    TestDistribution(hi.hash, 0, 10000000);
    
    return 0;
}

3. Comparing multiple hash functions:

#include "SMHasher.h"

int main(int argc, char** argv) {
    std::vector<HashInfo> hashFunctions = {
        { MurmurHash3_x86_32, "MurmurHash3_x86_32" },
        { CityHash32, "CityHash32" },
        { FNV1a, "FNV1a" }
    };
    
    for (const auto& hi : hashFunctions) {
        TestHashFunction(hi);
    }
    
    return 0;
}

Getting Started

To use SMHasher:

1. Clone the repository:

   git clone https://github.com/aappleby/smhasher.git
   

2. Build the project:

   cd smhasher
   mkdir build && cd build
   cmake ..
   make
   

3. Run the test suite:

   ./SMHasher
   

To test your own hash function, create a new C++ file with your implementation, include it in the project, and modify the main.cpp file to include your hash function in the test suite.