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Contributing to Bitcoin Cash Node

The Bitcoin Cash Node project welcomes contributors!

This guide is intended to help developers and others contribute effectively to Bitcoin Cash Node.

Communicating with the project

To get in contact with the Bitcoin Cash Node project, we monitor a number of resources.

Our main development repository is currently located at

https://gitlab.com/bitcoin-cash-node/bitcoin-cash-node

This features the project code, an issue tracker and facilities to see project progress and activities, even in detailed form such as individual change requests.

Users are free to submit issues or comment on existing ones - all that is needed is a GitLab account which can be freely registered (use the 'Register' button on the GitLab page).

In addition to the project repository, we have various other channels where project contributors can be reached.

Our main chat is at https://bitcoincashnode.slack.com, where we conduct our main development and interactive support for users of our node.

Other social media resources such as our Telegram and Twitter are linked from the project website at

https://bitcoincashnode.org

On all our channels, we seek to facilitate development of Bitcoin Cash Node, and to welcome and support people who wish to participate.

Please visit our channels to

  • Introduce yourself to other Bitcoin Cash Node contributors
  • Get help with your development environment
  • Discuss how to complete a patch.

It is not for:

  • Market discussion
  • Non-constructive criticism

Bitcoin Cash Node Development Philosophy

Bitcoin Cash Node aims for fast iteration and continuous integration.

This means that there should be quick turnaround for patches to be proposed, reviewed, and committed. Changes should not sit in a queue for long.

Expectations of contributors

Here are some tips to help keep the development working as intended. These are guidelines for the normal and expected development process. Developers can use their judgement to deviate from these guidelines when they have a good reason to do so.

  • Keep each change minimal and self-contained.
  • Don't amend a Merge Request after it has been accepted for merging unless with coordination with the maintainer(s)
  • Large changes should be broken into logical chunks that are easy to review, and keep the code in a functional state.
  • Do not mix moving stuff around with changing stuff. Do changes with renames on their own.
  • Sometimes you want to replace one subsystem by another implementation, in which case it is not possible to do things incrementally. In such cases, you keep both implementations in the codebase for a while, as described here
  • There are no "development" branches, all merge requests apply to the master branch, and should always improve it (no regressions).
  • As soon as you see a bug, you fix it. Do not continue on. Fixing the bug becomes the top priority, more important than completing other tasks.

Note: Code review is a burdensome but important part of the development process, and as such, certain types of merge requests are rejected. In general, if the improvements do not warrant the review effort required, the MR has a high chance of being rejected. Before working on a large or complex code change, it is recommended to consult with project maintainers about the desirability of the change, so you can be sure they are willing to spend the time required to review your work.

Critical code paths

Some code paths are more critical than others. This applies to code such as consensus, block template creation, mempool, relay policies and more. Changes to critical code paths really should inspire confidence. The following things can help inspire confidence:

  • Minimal, easily reviewable merge requests.
  • Extensive unit and/or functional tests.
  • Patience for reviewers
  • Appreciation for reviews.

Expectations of maintainers

These are guidelines for the normal and expected process for handling merge requests. Maintainers can use their judgement to deviate from these guidelines when they have a good reason to do so.

  • Try to guide contributors towards the goal of having their contributions merged.
  • Identify whether the intent of an MR is desirable, independent of its technical quality.
  • Merge accepted changes quickly after they are accepted.
  • If a merge has been done and breaks the build of master, fix it quickly. If it cannot be fixed quickly, revert it. It can be re-applied later when it no longer breaks the build.
  • Automate as much as possible, and spend time on things only humans can do.
  • Speak up or raise an issue if you anticipate a problem with a change.
  • Don't be afraid to say "NO", or "MAYBE, but...", if a change seems undesirable or if you otherwise have reservations/caveats/etc.

Here are some handy links for development practices aligned with Bitcoin Cash Node:

Getting set up with the Bitcoin Cash Node Repository

  1. Create an account at https://gitlab.com if you don't have one yet
  2. Install Git on your machine
    • Git documentation can be found at: https://git-scm.com
    • To install these packages on Debian or Ubuntu, type: sudo apt-get install git
  3. If you do not already have an SSH key set up, follow these steps:
    • Type: ssh-keygen -t rsa -b 4096 -C "your_email@example.com"
    • Enter a file in which to save the key (/home/username/.ssh/id_rsa): [Press enter]
    • NOTE: the path in the message shown above is specific to UNIX-like systems and may differ if you run on other platforms.
  4. Upload your SSH public key to GitLab
    • Go to: https://gitlab.com, log in
    • Under "User Settings", "SSH Keys", add your public key
    • Paste contents from: $HOME/.ssh/id_rsa.pub
  5. Create a personal fork of the Bitcoin Cash Node repository for your work
  6. Clone your personal work repository to your local machine:

    git clone git@gitlab.com:username/bitcoin-cash-node.git
    
  7. Set your checked out copy's upstream to our main project:

    git remote add upstream https://gitlab.com/bitcoin-cash-node/bitcoin-cash-node.git
    
  8. You may want to add the mreq alias to your .git/config:

    [alias]
    mreq = !sh -c 'git fetch $1 merge-requests/$2/head:mr-$1-$2 && git checkout mr-$1-$2' -
    

    This mreq alias can be used to easily check out Merge Requests from our main repository if you intend to test them or work on them. Example:

    $ git mreq upstream 93
    

    This will checkout merge-requests/93/head and put you in a branch called mr-origin-93. You can then proceed to test the changes proposed by that merge request.

  9. Code formatting tools

    During submission of patches, our GitLab process may refused code that is not styled according to our coding guidelines.

    To enforce Bitcoin Cash Node codeformatting standards, you may need to install clang-format-8, clang-tidy (version >=8), autopep8, flake8, phpcs and shellcheck on your system to format your code before submission as a Merge Request.

    To install clang-format-8 and clang-tidy on Ubuntu (>= 18.04+updates) or Debian (>= 10):

    sudo apt-get install clang-format-8 clang-tidy-8 clang-tools-8
    

    If not available in the distribution, clang-format-8 and clang-tidy can be installed from https://releases.llvm.org/download.html or https://apt.llvm.org.

    For example, for macOS:

    curl http://releases.llvm.org/8.0.0/clang+llvm-8.0.0-x86_64-apple-darwin.tar.xz | tar -xJv
    ln -s $PWD/clang+llvm-8.0.0-x86_64-apple-darwin/bin/clang-format /usr/local/bin/clang-format
    ln -s $PWD/clang+llvm-8.0.0-x86_64-apple-darwin/bin/clang-tidy /usr/local/bin/clang-tidy
    

    To install autopep8, flake8 and phpcs on Ubuntu:

    sudo apt-get install python-autopep8 flake8 php-codesniffer shellcheck
    
  10. Further task-specific dependencies

    In order to run the automated tests, you'll need the tools listed in the "dependencies" sections of these two documents:

    To produce coverage reports, you'll need the dependencies listed in:

    To run benchmarks, see the "LFS dependency" section in:

Working with The Bitcoin Cash Node Repository

A typical workflow would be:

  • Create a topic branch in Git for your changes

    git checkout -b 'my-topic-branch'

  • Make your changes, and commit them

    git commit -a -m 'my-commit'

  • Push the topic branch to your GitLab repository

    git push -u origin my-topic-branch

  • Then create a Merge Request (the GitLab equivalent of a Pull Request) from that branch in your personal repository. To do this, you need to sign in to GitLab, go to the branch and click the button which lets you create a Merge Request (you need to fill out at least title and description fields).

  • Work with us on GitLab to receive review comments, going back to the 'Make your changes' step above if needed to make further changes on your branch, and push them upstream as above. They will automatically appear in your Merge Request.

All Merge Requests should contain a commit with a test plan that details how to test the changes. In all normal circumstances, you should build and test your changes locally before creating a Merge Request. A merge request should feature a specific test plan where possible, and indicate which regression tests may need to be run.

If you have doubts about the scope of testing needed for your change, please contact our developers and they will help you decide.

  • For large changes, break them into several Merge Requests.

  • If you are making numerous changes and rebuilding often, it's highly recommended to install ccache (re-run cmake if you install it later), as this will help cut your re-build times from several minutes to under a minute, in many cases.

What to work on

If you are looking for a useful task to contribute to the project, a good place to start is the list of issues at https://gitlab.com/bitcoin-cash-node/bitcoin-cash-node/-/issues

Look for issues marked with a label 'good-first-issue'.

By contributing to this repository, you agree to license your work under the MIT license unless specified otherwise in contrib/debian/copyright or at the top of the file itself. Any work contributed where you are not the original author must contain its license header with the original author(s) and source.

Disclosure Policy

See DISCLOSURE_POLICY.