Horizon Documentation 1.21.1 Help

Contributing

Contributing to Horizon

Horizon is happy you're willing to contribute to our projects. We are usually very lenient with all submitted PRs, but there are still some guidelines you can follow to make the approval process go more smoothly.

Use a Personal Fork and not an Organization

HorizonAsync will routinely modify your PR, whether it's a quick rebase or to take care of any minor nitpicks we might have. Often, it's better for us to solve these problems for you than make you go back and forth trying to fix them yourself.

Unfortunately, if you use an organization for your PR, it prevents Horizon from modifying it. This requires us to manually merge your PR, resulting in us closing the PR instead of marking it as merged.

We much prefer to have PRs show as merged, so please do not use repositories on organizations for PRs.

See https://github.com/isaacs/github/issues/1681 for more information on the issue.

Requirements

To get started with PRing changes, you'll need the following software, most of which can be obtained in (most) package managers such as apt (Debian / Ubuntu; you will most likely use this for WSL), homebrew (macOS / Linux), and more:

  • git (package git everywhere);

  • A Java 21 or later JDK (packages vary, use Google/DuckDuckGo/etc.).

    • Adoptium has builds for most operating systems.

    • Horizon requires JDK 21 to build, however, makes use of Gradle's Toolchains feature to allow building with only JRE 11 or later installed. (Gradle will automatically provision JDK 21 for compilation if it cannot find an existing install).

Understanding Patches

Paper is mostly patches and extensions to Spigot. These patches/extensions are split into different directories which target certain parts of the code. These directories are:

  • Horizon-API - Modifications to Paper-API;

  • Horizon-Server - Modifications to Paper-Server.

Because the entire structure is based on patches and git, a basic understanding of how to use git is required. A basic tutorial can be found here

Assuming you have already forked the repository:

  1. Clone your fork to your local machine;

  2. Type ./gradlew applyPatches in a terminal to apply the changes from upstream. On Windows, replace the ./ with .\ at the beginning for all gradlew commands;

  3. cd into Horizon-Server for server changes, and Horizon-API for API changes.

Horizon-Server and Horizon-API aren't git repositories in the traditional sense:

  • base points to the unmodified source before Horizon patches have been applied.

  • Each commit after base is a patch.

Adding Patches

Adding patches to Horizon is very simple:

  1. Modify Horizon-Server and/or Horizon-API with the appropriate changes;

  2. Type git add . inside these directories to add your changes;

  3. Run git commit with the desired patch message;

  4. Run ./gradlew rebuildPatches in the main directory to convert your commit into a new patch;

  5. PR the generated patch file(s) back to this repository.

Your commit will be converted into a patch that you can then PR into Horizon.

Modifying Patches

Manual method

  1. Make your change while at HEAD;

  2. Make a temporary commit. You don't need to make a message for this;

  3. Type git rebase -i base, move (cut) your temporary commit and move it under the line of the patch you wish to modify;

  4. Change the pick to the appropriate action:

    1. f/fixup: Merge your changes into the patch without touching the message.

    2. s/squash: Merge your changes into the patch and use your commit message and subject.

  5. Type ./gradlew rebuildPatches in the root directory;

    • This will modify the appropriate patches based on your commits.

  6. PR your modified patch file(s) back to this repository.

  1. Make your change while at HEAD;

  2. Make a fixup commit. git commit -a --fixup <hashOfPatchToFix>;

    • You can also use --squash instead of --fixup if you want the commit message to also be changed.

    • You can get the hash by looking at git log or git blame; your IDE can assist you too.

    • Alternatively, if you only know the name of the patch, you can do git commit -a --fixup "Subject of Patch name".

  3. Rebase with autosquash: git rebase -i --autosquash base. This will automatically move your fixup commit to the right place, and you just need to "save" the changes.

  4. Type ./gradlew rebuildPatches in the root directory;

    • This will modify the appropriate patches based on your commits.

  5. PR your modified patch file(s) back to this repository.

Rebasing PRs

Steps to rebase a PR to include the latest changes from master.
These steps assume the origin remote is your fork of this repository and upstream is the official Horizon repository.

  1. Pull the latest changes from upstreams master: git checkout master && git pull upstream master.

  2. Checkout feature/fix branch and rebase on master: git checkout patch-branch && git rebase master.

  3. Apply updated patches: ./gradlew applyPatches.

  4. If there are conflicts, fix them.

  5. If your PR creates new patches instead of modifying existing ones, in both the Horizon-Server and Horizon-API directories, ensure your newly-created patch is the last commit by either:

    • Renaming the patch file with a large 4-digit number in front (e.g. 9999-Patch-to-add-some-new-stuff.patch), and re-applying patches.

    • Running git rebase --interactive base and moving the commits to the end.

  6. Rebuild patches: ./gradlew rebuildPatches.

  7. Commit modified patches.

  8. Force push changes: git push --force.

Formatting

All modifications to non-Horizon files should be marked. The one exception to this is when modifying javadoc comments, which should not have these markers.

  • You need to add a comment with a short and identifiable description of the patch: // Horizon start - <COMMIT DESCRIPTION>

    • The comments should generally be about the reason the change was made, what it was before, or what the change is.

    • After the general commit description, you can add additional information either after a ; or in the next line.

  • Multi-line changes start with // Horizon start - <COMMIT DESCRIPTION> and end with // Horizon end - <COMMIT DESCRIPTION>.

  • One-line changes should have // Horizon - <COMMIT DESCRIPTION> at the end of the line.

Here's an example of how to mark changes by Horizon:

entity.getWorld().dontBeStupid(); // Horizon - Was beStupid(), which is bad entity.getFriends().forEach(Entity::explode); entity.updateFriends(); // Horizon start - Use plugin-set spawn // entity.getWorld().explode(entity.getWorld().getSpawn()); Location spawnLocation = ((CraftWorld)entity.getWorld()).getSpawnLocation(); entity.getWorld().explode(new BlockPosition(spawnLocation.getX(), spawnLocation.getY(), spawnLocation.getZ())); // Horizon end - Use plugin-set spawn

We generally follow the usual Java style (aka. Oracle style), or what is programmed into most IDEs and formatters by default. There are a few notes, however:

  • It is fine to go over 80 lines as long as it doesn't hurt readability.


    There are exceptions, especially in Spigot-related files

  • When in doubt or the code around your change is in a clearly different style, use the same style as the surrounding code.

  • var usage is heavily discouraged, as it makes reading patch files a lot harder and can lead to confusion during updates due to changed return types. The only exception to this is if a line would otherwise be way too long/filled with hard to parse generics in a case where the base type itself is already obvious

Testing API changes

Using the Horizon Test Plugin

The Horizon project has a test-plugin module for easily testing out API changes and additions. To use the test plugin, enable it in test-plugin.settings.gradle.kts, which will be generated after running Gradle at least once. After this, you can edit the test plugin, and run a server with the plugin using ./gradlew runDev (or any of the other Horizon run tasks).

Publishing to Maven local (use in external plugins)

To build and install the Horizon APIs and Server to your local Maven repository, do the following:

  • Run ./gradlew publishToMavenLocal in the base directory.

If you use Gradle to build your plugin:

  • Add mavenLocal() as a repository. Gradle checks repositories in the order they are declared, so if you also have the Horizon repository added, put the local repository above Horizon's.

  • Make sure to remove mavenLocal() when you are done testing, see the Gradle docs for more details.

If you use Maven to build your plugin:

  • If you later need to use the Horizon-API, you might want to remove the jar from your local Maven repository.


    If you use Windows and don't usually build using WSL, you might not need to do this.

Last modified: 06 June 2024
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