You are more than welcome to participate in rdedup development.
I advise you to join rdedup gitter channel and say hello.
rdedup is structured as rather typical Rust project. It is split between
binary crate and a library. The library is the more interesting part.
Check out wiki and especially Rust's fearless concurrency in rdedup for some design information.
More design documentation should follow. docs subdirectory would be a place to put it.
You can generate documentation that includes private items:
cargo rustdoc -- --no-defaults --passes "collapse-docs" --passes "unindent-comments"
cd lib
cargo rustdoc -- --no-defaults --passes "collapse-docs" --passes "unindent-comments"
cd ..
xdg-open target/doc/rdedup/index.html
Most unit tests are implemented in rdedup-lib.
scripts/e2e-test.sh and scripts/e2e-test-full.sh implement some
basic data integrity tests, exercising all possible configuration options.
./tester implements a simple program that drives rdedup with random
operations on the repo.