85 lines
3.6 KiB
Rust
85 lines
3.6 KiB
Rust
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// nih-plug: plugins, but rewritten in Rust
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// Copyright (C) 2022 Robbert van der Helm
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//! Different contexts the plugin can use to make callbacks to the host in different...contexts.
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use std::sync::Arc;
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#[cfg(all(target_family = "unix", not(target_os = "macos")))]
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mod linux;
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#[cfg(all(target_family = "unix", not(target_os = "macos")))]
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pub(crate) use linux::LinuxEventLoop as OsEventLoop;
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// TODO: ProcessContext for parameter automation and sending events
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// TODO: GuiContext for GUI parameter automation and resizing
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pub(crate) const TASK_QUEUE_CAPACITY: usize = 512;
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/// General callbacks the plugin can make during its lifetime. This is passed to the plugin during
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/// [Plugin::initialize].
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///
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/// # Safety
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///
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/// This context is passed to be stored by the plugin, and it may thus not outlive the wrapper.
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/// Hence the use of reference counted smart pointers. The implementing wrapper needs to be able to
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/// handle concurrent requests, and it should perform the actual callback within
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/// [MainThreadQueue::do_maybe_async].
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pub unsafe trait ProcessContext {
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/// Update the current latency of the plugin. If the plugin is currently processing audio, then
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/// this may cause audio playback to be restarted.
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fn set_latency_samples(self: &Arc<Self>, samples: u32);
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}
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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 queue should be realtime safe. This thread
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/// queue should be created during the wrapper's initial initialization on the main 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.
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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,
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E: MainThreadExecutor<T>,
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{
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/// Create a main thread tasks queue for the given executor. The thread this is called on will
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/// be designated as the main thread, so this should be called when constructing the wrapper.
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///
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/// TODO: Spawn, and update docs
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fn new_and_spawn(executor: Arc<E>) -> Self;
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/// Either post the function to a queue so it can be run later from the main thread using a
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/// timer, or run the function directly if this is the main thread. This needs to be callable at
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/// any time withotu blocking.
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///
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/// If the task queue was 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 even loop's main thread. This is usually the thread the
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/// event loop instance wel 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.
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fn execute(&self, task: T);
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}
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