Bartłomiej Dach
43897457fb
The reproduction scenario for the subscription leak is as follows: 1. Switch to a scrolling ruleset (anything but osu! from the standard ones). 2. Select a beatmap to edit. 3. Load the composer. 4. Go to timing tab. 5. Change a timing point. 6. Go back to the composer. At this point, `EditorChangeHandler.OnStateChange` will have multiple of the same delegate in the invocation list. <img width="691" height="311" alt="Screenshot 2026-03-05 at 11 15 55" src="https://github.com/user-attachments/assets/57788341-9573-48f1-b360-f21036891081" /> That in turn is caused by the fact that changing a timing point *does* incur a full reload of the composer via the following flow: https://github.com/ppy/osu/blob/15b6e28ebe888b1a87574891be1a0db3b04093b7/osu.Game/Rulesets/Edit/ScrollingHitObjectComposer.cs#L145 https://github.com/ppy/osu/blob/64a29313a852d50095ae4b7ea8f22fde23aa634f/osu.Game/Screens/Edit/Editor.cs#L1137-L1145 This flow is my "fault"; see https://github.com/ppy/osu/pull/28444. The reason why a full composer reload is used is not clear to my recollection at this time, but it is likely because it's just the least likely to fail. A smarter solution that wouldn't require a full reload would also entail checking that there exists a safe insertion point that allows replacing timing points in a way that will reflect everywhere it must. Including all of the `IScrollingAlgorithm` machinery and such. In general it is not uncommon in the codebase to not bother to clean up some event callbacks if it is implicitly or explicitly guaranteed that both objects bound by the callback will always get disposed in tandem at the same time. This *was* true with this particular flow to a point, which was until that full composer reload was implemented. <details> <summary>To address the elephant in the room</summary> Someone will inevitably notice https://github.com/ppy/osu/pull/36824 which was a clanked pull request pointing out this leak. And then someone will inevitably call this "AI discrimination"! *Gasp!* So first of all, let me stop you right there. Yes, as far as I am _personally_ concerned, it is "AI discrimination". I invoke the full force of the Butlerian Jihad. The clank army's goal is to eradicate my job and make me work in an Amazon warehouse instead. Or, if not that, at least my job is to be rid of all remnants of fun I still get from it and for me to be reduced to that one guy from the meme "i guess we're doin circles now". You know the one. I resent this. You attack me directly. I do not perceive the need to meet you halfway or be civil. That said, I have too much respect for the users of this software to leave reports of potentially real issues unchecked. So I did check, and it was real. And you know what? Good job to the clanker. It did what it was designed to do: it parsed a code file, recognised a hole in a pattern it was designed to recognise, and invoked forms of language given to it to communicate this to the meatbag that opened that PR. And here's the thing: my primary issue is with that meatbag that opened that PR. That meatbag served no functional purpose in any of this. The meatbag took a hose that spews 90% water and 10% raw sewage at random intervals and pointed it at my house directly, claiming that they just want to clean it. At no point did the meatbag appear to have the common decency to pull out a container, pour some magic liquid out, check if there's sewage in it, and filter it out if there is any. But no, that would take *effort* and *thought*, would it not? The *effort* and *thought* that is required of *me* to *review* the clanker's work? The PR had no reproduction scenario, and had testing checkboxes that were presumably meant for *me* to check off. Why is it *my* job to figure all of this out rather than the submitter meatbag's? I do *not* have obligations towards spew-hose-pointing meatbags. Point that hose at your own backyard at your peril. If you *actually manage* to get the clanker to filter out *all* of the spew without fail itself, my only win condition is gone. But it is not yet that time. So at least have the decency to check for the spew yourself, rather than telling the clanker to put checkboxes in the PR descriptions telling *me* to check for it. </details>
osu!
A free-to-win rhythm game. Rhythm is just a click away!
This is the future – and final – iteration of the osu! game client which marks the beginning of an open era! Currently known by and released under the release codename "lazer". As in sharper than cutting-edge.
Status
This project is under constant development, but we do our best to keep things in a stable state. Players are encouraged to install from a release alongside their stable osu! client. This project will continue to evolve until we eventually reach the point where most users prefer it over the previous "osu!stable" release.
A few resources are available as starting points to getting involved and understanding the project:
- Detailed release changelogs are available on the official osu! site.
- You can learn more about our approach to project management.
- Track our current efforts towards improving the game.
Running osu!
If you are just looking to give the game a whirl, you can grab the latest release for your platform:
Latest release:
| Windows 10+ (x64) | macOS 12+ (Intel, Apple Silicon) | Linux (x64) | iOS 13.4+ | Android 5+ |
|---|
You can also generally download a version for your current device from the osu! site.
If your platform is unsupported or not listed above, there is still a chance you can run the release or manually build it by following the instructions below.
For iOS/iPadOS users: The iOS testflight link fills up very fast (Apple has a hard limit of 10,000 users). We reset it occasionally. Please do not ask about this. Check back regularly for link resets or follow peppy on twitter for announcements. Our goal is to get the game on mobile app stores very soon so we don't have to live with this limitation.
Developing a custom ruleset
osu! is designed to allow user-created gameplay variations, called "rulesets". Building one of these allows a developer to harness the power of the osu! beatmap library, game engine, and general UX for a new style of gameplay. To get started working on a ruleset, we have some templates available here.
You can see some examples of custom rulesets by visiting the custom ruleset directory.
Developing osu!
Prerequisites
Please make sure you have the following prerequisites:
- A desktop platform with the .NET 8.0 SDK installed.
When working with the codebase, we recommend using an IDE with intelligent code completion and syntax highlighting, such as the latest version of Visual Studio, JetBrains Rider, or Visual Studio Code with the EditorConfig and C# Dev Kit plugin installed.
Downloading the source code
Clone the repository:
git clone https://github.com/ppy/osu
cd osu
To update the source code to the latest commit, run the following command inside the osu directory:
git pull
Building
From an IDE
You should load the solution via one of the platform-specific .slnf files, rather than the main .sln. This will reduce dependencies and hide platforms that you don't care about. Valid .slnf files are:
osu.Desktop.slnf(most common)osu.Android.slnfosu.iOS.slnf
Run configurations for the recommended IDEs (listed above) are included. You should use the provided Build/Run functionality of your IDE to get things going. When testing or building new components, it's highly encouraged you use the osu! (Tests) project/configuration. More information on this is provided below.
To build for mobile platforms, you will likely need to run sudo dotnet workload restore if you haven't done so previously. This will install Android/iOS tooling required to complete the build.
From CLI
You can also build and run osu! from the command-line with a single command:
dotnet run --project osu.Desktop
When running locally to do any kind of performance testing, make sure to add -c Release to the build command, as the overhead of running with the default Debug configuration can be large (especially when testing with local framework modifications as below).
If the build fails, try to restore NuGet packages with dotnet restore.
Testing with resource/framework modifications
Sometimes it may be necessary to cross-test changes in osu-resources or osu-framework. This can be quickly achieved using included commands:
Windows:
UseLocalFramework.ps1
UseLocalResources.ps1
macOS / Linux:
UseLocalFramework.sh
UseLocalResources.sh
Note that these commands assume you have the relevant project(s) checked out in adjacent directories:
|- osu // this repository
|- osu-framework
|- osu-resources
Code analysis
Before committing your code, please run a code formatter. This can be achieved by running dotnet format in the command line, or using the Format code command in your IDE.
We have adopted some cross-platform, compiler integrated analyzers. They can provide warnings when you are editing, building inside IDE or from command line, as-if they are provided by the compiler itself.
JetBrains ReSharper InspectCode is also used for wider rule sets. You can run it from PowerShell with .\InspectCode.ps1. Alternatively, you can install ReSharper or use Rider to get inline support in your IDE of choice.
Contributing
When it comes to contributing to the project, the two main things you can do to help out are reporting issues and submitting pull requests. Please refer to the contributing guidelines to understand how to help in the most effective way possible.
If you wish to help with localisation efforts, head over to crowdin.
We love to reward quality contributions. If you have made a large contribution, or are a regular contributor, you are welcome to submit an expense via opencollective. If you have any questions, feel free to reach out to peppy before doing so.
Licence
osu!'s code and framework are licensed under the MIT licence. Please see the licence file for more information. tl;dr you can do whatever you want as long as you include the original copyright and license notice in any copy of the software/source.
Please note that this does not cover the usage of the "osu!" or "ppy" branding in any software, resources, advertising or promotion, as this is protected by trademark law.
Please also note that game resources are covered by a separate licence. Please see the ppy/osu-resources repository for clarifications.