66 lines
2.8 KiB
Rust
66 lines
2.8 KiB
Rust
//! An internal event loop for spooling tasks to the/a GUI thread.
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use std::sync::Weak;
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#[cfg(all(target_family = "unix", not(target_os = "macos")))]
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mod linux;
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// For now, also use the Linux event loop on macOS so it at least compiles
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#[cfg(target_os = "macos")]
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mod linux;
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#[cfg(target_os = "windows")]
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mod windows;
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#[cfg(all(target_family = "unix", not(target_os = "macos")))]
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pub(crate) use self::linux::LinuxEventLoop as OsEventLoop;
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// For now, also use the Linux event loop on macOS so it at least compiles
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#[cfg(target_os = "macos")]
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pub(crate) use self::linux::LinuxEventLoop as OsEventLoop;
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#[cfg(target_os = "windows")]
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pub(crate) use self::windows::WindowsEventLoop as OsEventLoop;
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pub(crate) const TASK_QUEUE_CAPACITY: usize = 512;
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/// A trait describing the functionality of the platform-specific event loop that can execute tasks
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/// of type `T` in executor `E`. Posting a task to the internal task queue should be realtime safe.
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/// This event loop should be created during the wrapper's initial initialization on the main
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/// thread.
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///
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/// This is never used generically, but having this as a trait will cause any missing functions on
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/// an implementation to show up as compiler errors even when using a different platform. And since
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/// the tasks and executor will be sent to a thread, they need to have static lifetimes.
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///
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/// TODO: At some point rethink the design to make it possible to have a singleton message queue for
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/// all instances of a plugin.
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pub(crate) trait EventLoop<T, E>
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where
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T: Send + 'static,
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E: MainThreadExecutor<T> + 'static,
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{
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/// Create and start a new event loop. The thread this is called on will be designated as the
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/// main thread, so this should be called when constructing the wrapper.
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fn new_and_spawn(executor: Weak<E>) -> Self;
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/// Either post the function to the task queue so it can be delegated to the main thread, or
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/// execute the task directly if this is the main thread. This function needs to be callable at
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/// any time without blocking.
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///
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/// If the task queue is full, then this will return false.
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#[must_use]
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fn do_maybe_async(&self, task: T) -> bool;
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/// Whether the calling thread is the event loop's main thread. This is usually the thread the
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/// event loop instance was initialized on.
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fn is_main_thread(&self) -> bool;
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}
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/// Something that can execute tasks of type `T`.
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pub(crate) trait MainThreadExecutor<T>: Send + Sync {
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/// Execute a task on the current thread. This should only be called from the main thread.
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///
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/// # Safety
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///
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/// This is not actually unsafe in the typical Rust sense. But the implemnting function will
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/// assume (and can only assume) that this is called from the main thread.
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unsafe fn execute(&self, task: T);
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}
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