43d1a8040d
This change ensures that the event loop prioritizes enqueueing another render or handling user input over executing runnables. It's a subtle change as a result of a week of digging into performance on X11. It's also not perfect: ideally we'd get rid of the intermediate channel here and had more control over when and how we run runnables vs. X11 events, but I think short of rewriting how we use an event loop, this is good cost/benefit change. To illustrate: Before this change, it was possible to block the app from rendering for a long time by just creating a ton of futures that were executed on the "main" thread (we don't have a "main" thread on Linux, but we have a single thread in which we run the event loop). That was relatively easy to reproduce by opening the `zed` repository and starting `rust-analyzer`: at some point `rust-analyzer` sends us so many notifications, that are all handled in futures, that the event loop is busy just working off the runnables, never getting to the events that X11 sends us or our own timer to re-enqueue another render. When you put print statements into the code to show when which event was handled, you'd see something like this **before this change**: ``` [ ... hundreds of runnable.run() ... ] runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() new render tick timer. lag: 56.942049ms X11 event new render tick timer. lag: 9.668µs X11 event new render tick timer. lag: 9.955µs X11 event runnable.run() runnable.run() runnable.run() runnable.run() new render tick timer. lag: 12.462µs X11 event new render tick timer. lag: 14.868µs X11 event new render tick timer. lag: 11.234µs X11 event new render tick timer. lag: 11.681µs X11 event new render tick timer. lag: 13.926µs X11 event ``` Note the `lag: 56ms`: that's the difference between when we wanted to execute the callback that enqueues another render and when it ran. Longer lags are possible, this is just the first one I grabbed from the logs. Now, compare this with the logs **after this change**: ``` runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() new render tick timer. lag: 36.051µs runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() X11 event runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() runnable.run() ``` In-between many `runnable.run()` we'll always handle events. So, in essence, what this change does is to introduce 2 priorities into the X11 event queue: - high: X11 events (user events, render events, ...), render tick, XIM events, ... - low: all async rust code I've tested this with a debug build and release build and I think the app now feels more responsive. It doesn't feel perfect still, especially in the slow debug builds, but I couldn't observe 10s lockups anymore. Since it's a pretty small change, I think we should go for it and see how it behaves. Thanks to @maan2003 this now also includes the same change to Wayland. Release Notes: - N/A --------- Co-authored-by: maan2003 <manmeetmann2003@gmail.com> |
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| README.md | ||
Welcome to GPUI!
GPUI is a hybrid immediate and retained mode, GPU accelerated, UI framework for Rust, designed to support a wide variety of applications.
Getting Started
GPUI is still in active development as we work on the Zed code editor and isn't yet on crates.io. You'll also need to use the latest version of stable rust and be on macOS. Add the following to your Cargo.toml:
gpui = { git = "https://github.com/zed-industries/zed" }
Everything in GPUI starts with an App. You can create one with App::new(), and kick off your application by passing a callback to App::run(). Inside this callback, you can create a new window with AppContext::open_window(), and register your first root view. See gpui.rs for a complete example.
The Big Picture
GPUI offers three different registers depending on your needs:
-
State management and communication with Models. Whenever you need to store application state that communicates between different parts of your application, you'll want to use GPUI's models. Models are owned by GPUI and are only accessible through an owned smart pointer similar to an
Rc. See theapp::model_contextmodule for more information. -
High level, declarative UI with Views. All UI in GPUI starts with a View. A view is simply a model that can be rendered, via the
Rendertrait. At the start of each frame, GPUI will call this render method on the root view of a given window. Views build a tree ofelements, lay them out and style them with a tailwind-style API, and then give them to GPUI to turn into pixels. See thedivelement for an all purpose swiss-army knife of rendering. -
Low level, imperative UI with Elements. Elements are the building blocks of UI in GPUI, and they provide a nice wrapper around an imperative API that provides as much flexibility and control as you need. Elements have total control over how they and their child elements are rendered and can be used for making efficient views into large lists, implement custom layouting for a code editor, and anything else you can think of. See the
elementmodule for more information.
Each of these registers has one or more corresponding contexts that can be accessed from all GPUI services. This context is your main interface to GPUI, and is used extensively throughout the framework.
Other Resources
In addition to the systems above, GPUI provides a range of smaller services that are useful for building complex applications:
-
Actions are user-defined structs that are used for converting keystrokes into logical operations in your UI. Use this for implementing keyboard shortcuts, such as cmd-q. See the
actionmodule for more information. -
Platform services, such as
quit the apporopen a URLare available as methods on theapp::AppContext. -
An async executor that is integrated with the platform's event loop. See the
executormodule for more information., -
The
[gpui::test]macro provides a convenient way to write tests for your GPUI applications. Tests also have their own kind of context, aTestAppContextwhich provides ways of simulating common platform input. Seeapp::test_contextandtestmodules for more details.
Currently, the best way to learn about these APIs is to read the Zed source code, ask us about it at a fireside hack, or drop a question in the Zed Discord. We're working on improving the documentation, creating more examples, and will be publishing more guides to GPUI on our blog.