ArKanjo is a CLI tool designed to help developers find code duplication within their codebases, specifically within the scope of functions.

The current functionalities of the tool are:

• Explore code duplication in a codebase, with a limited number of filters available to the user.

• Find all functions that are duplicates of a function specified by the user.

• Create a report detailing the number of duplications in the codebase, separated by folder.

Some other commands were used for the creator's master's degree, but they are not relevant to end-users.

The tool currently supports only the languages provided by the Tree-sitter API; these must be explicitly added to the config.json file.

Similarity

The tool currently uses the concept of similarity. A user can pass a similarity threshold to the tool, which is a number between 0.0 and 100.0. This threshold is used to limit what the tool considers a duplication.

If the threshold is set to 0.0, everything is considered a duplication. If the threshold is set to 100.0, only completely equal functions are considered duplications. In its current state, the tool provides good results with similarity thresholds around 90.0.

The ArKanjo tool uses the Duplicate Code Detection Tool as a subroutine to generate the similarity metrics.

For more details about the similarity model, see docs/similarity.md.

Insights from the Linux Kernel

ArKanjo was used in an ethnographic study involving real contributions to the Linux kernel.
The results show that code duplication is not always undesirable and depends on context.

Key findings from interactions with maintainers:

• Driver Forking (T1)
  Code duplication is sometimes intentional. Entire drivers are cloned to serve as independent baselines.

• Readability over Deduplication (T2)
  Maintainers often prefer duplicated code if it improves clarity and reduces cognitive load.

• Integration Overhead (T3)
  Small deduplication changes may be rejected due to the cost of integrating and maintaining them.

• Performance Trade-offs (T4)
  In low-level code, duplication may be preferred to avoid performance regressions.

These findings challenge the strict application of the DRY principle in large-scale systems.

Requirements

The tool has only been tested on Ubuntu operating systems. An installation guide could be included.

How to install

Run the following commands in the terminal to install the dependencies:

pip3 install --user nltk
pip3 install --user gensim
pip3 install --user astor
python3 -m nltk.downloader punkt

Download the source code:

git clone https://github.com/arkanjo-tool/arkanjo.git
cd arkanjo

Build the binary:

mkdir build
cd build

cmake ..
cmake --build .

The binaries will be generated in the build/ directory.

How to Run

Preprocessing and Cache

The tool is designed with heavy preprocessing, which enables it to answer different kinds of queries quickly. Cache files are stored on your system and can grow significantly depending on codebase size.

To perform the preprocessing, execute the preprocessor:

arkanjo-preprocessor build

• The preprocessor will ask for the complete path to the codebase you want to analyze and the desired similarity threshold.
• Cache fallback: ./tmp/arkanjo

Execute the tool

To execute the tool's commands, you need to run a command that follows this format:

arkanjo <command> [command_parameters] [--preprocessor] [-S <SIMILARITY>]

If the preprocessor has not been run yet, the tool will automatically execute it.

The parameters common to all commands are:

• --preprocessor: Forces the preprocessor to execute.

• -S <SIMILARITY>: Changes the similarity threshold to SIMILARITY for the current command only.

Commands (summary)

Command	Purpose	Example
explorer	Explore duplicated functions detected in the project	arkanjo explorer -l 10 -s
function	Search for functions using a substring match.	arkanjo function offset_to_id
duplication	Analyze and report duplicated lines across the codebase, grouped by folder hierarchy.	arkanjo duplication

For full details and options for each command, run:

arkanjo <command> --help