benchmark: clarify reference

Author: ggcr

benchmark/README.md

@@ -0,0 +1,34 @@
+# Benchmark
+
+This directory benchmarks multiple S3 client implementations by lowering them all to a shared C ABI and loading them as shared libraries at runtime
+
+The idea is:
+
+- each implementation exports the same symbols, currently `initClient` and `get_object`
+- each implementation is compiled into its own shared library in `build/`
+- the host test/benchmark code loads those libraries with `dlopen`/`dlsym`
+- once everything looks the same at the ABI boundary, the host can exercise all implementations uniformly
+
+This keeps the benchmark harness language-agnostic. The host does not need to know whether the underlying implementation was written in C++, Go, or something else. It only cares that the shared library exports the expected symbols with the expected ABI.
+
+## Prerequisite
+
+A local MinIO instance is expected to be running already. The current `test.cpp` uses `s3cpp` itself as a preamble to create basic scaffolding for the tests before calling each shared library implementation.
+
+## Usage
+
+Build all currently enabled shared libraries:
+
+```bash
+make
+```
+
+Tests that shared libraries are built:
+```bash
+make test
+./build/test
+```
+
+## Notes
+
+- Benchmark infra is inspired by @strager work [Faster than Rust and C++: the PERFECT hash table](https://www.youtube.com/watch?v=DMQ_HcNSOAI) video ([code](https://github.com/strager/perfect-hash-tables))