FlexHASH

Experiments in fast C++ hash containers.

Contents

Directory	What it is
flex_hash/	A header-only, C++17 hash map/set whose storage layout is chosen at compile time from a hash_policy tag. See flex_hash/README.md.
hash_bench/	A benchmark comparing flex_hash against std::unordered_*, ankerl unordered_dense, ska flat_hash_map, and emhash. See hash_bench/RESULTS.md.

Quick start

flex_hash is header-only with no external dependencies:

#include <flex/flex_hash.h>

flex::hash_map<uint64_t, uint64_t> m;   // BALANCED (default)
m.insert_or_assign(1, 100);

g++ -std=c++17 -O2 -Iflex_hash/include  your_program.cpp

Running the benchmark

The third-party libraries are not vendored. Fetch them on demand, then build:

cd hash_bench
./fetch_deps.sh     # clones ankerl / emhash / ska into deps/  (also auto-run by make)
make run