diff --git a/src/context.rs b/src/context.rs
new file mode 100644
index 00000000..84f026fe
--- /dev/null
+++ b/src/context.rs
@@ -0,0 +1,84 @@
+// nih-plug: plugins, but rewritten in Rust
+// Copyright (C) 2022 Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see .
+
+//! Different contexts the plugin can use to make callbacks to the host in different...contexts.
+
+use std::sync::Arc;
+
+#[cfg(all(target_family = "unix", not(target_os = "macos")))]
+mod linux;
+
+#[cfg(all(target_family = "unix", not(target_os = "macos")))]
+pub(crate) use linux::LinuxEventLoop as OsEventLoop;
+
+// TODO: ProcessContext for parameter automation and sending events
+// TODO: GuiContext for GUI parameter automation and resizing
+
+pub(crate) const TASK_QUEUE_CAPACITY: usize = 512;
+
+/// General callbacks the plugin can make during its lifetime. This is passed to the plugin during
+/// [Plugin::initialize].
+///
+/// # Safety
+///
+/// This context is passed to be stored by the plugin, and it may thus not outlive the wrapper.
+/// Hence the use of reference counted smart pointers. The implementing wrapper needs to be able to
+/// handle concurrent requests, and it should perform the actual callback within
+/// [MainThreadQueue::do_maybe_async].
+pub unsafe trait ProcessContext {
+ /// Update the current latency of the plugin. If the plugin is currently processing audio, then
+ /// this may cause audio playback to be restarted.
+ fn set_latency_samples(self: &Arc, samples: u32);
+}
+
+/// A trait describing the functionality of the platform-specific event loop that can execute tasks
+/// of type `T` in executor `E`. Posting a task to the queue should be realtime safe. This thread
+/// queue should be created during the wrapper's initial initialization on the main thread.
+///
+/// This is never used generically, but having this as a trait will cause any missing functions on
+/// an implementation to show up as compiler errors even when using a different platform.
+///
+/// TODO: At some point rethink the design to make it possible to have a singleton message queue for
+/// all instances of a plugin.
+pub(crate) trait EventLoop
+where
+ T: Send,
+ E: MainThreadExecutor,
+{
+ /// Create a main thread tasks queue for the given executor. The thread this is called on will
+ /// be designated as the main thread, so this should be called when constructing the wrapper.
+ ///
+ /// TODO: Spawn, and update docs
+ fn new_and_spawn(executor: Arc) -> Self;
+
+ /// Either post the function to a queue so it can be run later from the main thread using a
+ /// timer, or run the function directly if this is the main thread. This needs to be callable at
+ /// any time withotu blocking.
+ ///
+ /// If the task queue was full, then this will return false.
+ #[must_use]
+ fn do_maybe_async(&self, task: T) -> bool;
+
+ /// Whether the calling thread is the even loop's main thread. This is usually the thread the
+ /// event loop instance wel initialized on.
+ fn is_main_thread(&self) -> bool;
+}
+
+/// Something that can execute tasks of type `T`.
+pub(crate) trait MainThreadExecutor: Send + Sync {
+ /// Execute a task on the current thread.
+ fn execute(&self, task: T);
+}
diff --git a/src/context/linux.rs b/src/context/linux.rs
new file mode 100644
index 00000000..61bdda8f
--- /dev/null
+++ b/src/context/linux.rs
@@ -0,0 +1,127 @@
+// nih-plug: plugins, but rewritten in Rust
+// Copyright (C) 2022 Robbert van der Helm
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see .
+
+//! An event loop impelemntation for Linux. APIs on Linux are generally thread safe, so the context
+//! of a main thread does not exist there. Because of that, this mostly just serves as a way to
+//! delegate expensive processing to another thread.
+
+use crossbeam::channel;
+use std::sync::Arc;
+use std::thread::{self, JoinHandle, ThreadId};
+
+use crate::nih_log;
+
+use super::{EventLoop, MainThreadExecutor};
+
+/// See [super::EventLoop].
+pub(crate) struct LinuxEventLoop {
+ /// The thing that ends up executing these tasks. The tasks are usually executed from the worker
+ /// thread, but if the current thread is the main thread then the task cna also be executed
+ /// directly.
+ executor: Arc,
+
+ /// The ID of the main thread. In practice this is the ID of the thread that created this task
+ /// queue.
+ main_thread_id: ThreadId,
+
+ /// A thread that act as our worker thread. When [do_maybe_async] is called, this thread will be
+ /// woken up to execute the task on the executor. This is wrapped in an `Option` so the thread
+ /// can be taken out of it and joined when this struct gets dropped.
+ worker_thread: Option>,
+ /// A channel for waking up the worker thread and having it perform one of the tasks from
+ /// [Message].
+ worker_thread_channel: channel::Sender>,
+}
+
+/// A message for communicating with the worker thread.
+enum Message {
+ /// A new task for the event loop to execute.
+ Task(T),
+ /// Shut down the worker thread.
+ Shutdown,
+}
+
+impl EventLoop for LinuxEventLoop
+where
+ T: Send,
+ E: MainThreadExecutor,
+{
+ fn new_and_spawn(executor: Arc) -> Self {
+ let (sender, receiver) = channel::bounded(super::TASK_QUEUE_CAPACITY);
+
+ Self {
+ executor: executor.clone(),
+ main_thread_id: thread::current().id(),
+ // With our drop implementation we guarentee that this thread never outlives this struct
+ worker_thread: Some(unsafe {
+ thread::Builder::new()
+ .name(String::from("worker"))
+ // FIXME: Find another way to bind a thread lifetime to this struct without a
+ // nightly-only fature
+ .spawn_unchecked(move || worker_thread(receiver, executor))
+ .expect("Could not spawn worker thread")
+ }),
+ worker_thread_channel: sender,
+ }
+ }
+
+ fn do_maybe_async(&self, task: T) -> bool {
+ if self.is_main_thread() {
+ self.executor.execute(task);
+ true
+ } else {
+ self.worker_thread_channel
+ .try_send(Message::Task(task))
+ .is_ok()
+ }
+ }
+
+ fn is_main_thread(&self) -> bool {
+ thread::current().id() == self.main_thread_id
+ }
+}
+
+impl Drop for LinuxEventLoop {
+ fn drop(&mut self) {
+ self.worker_thread_channel
+ .send(Message::Shutdown)
+ .expect("Failed while sending worker thread shutdown request");
+ if let Some(join_handle) = self.worker_thread.take() {
+ join_handle.join().expect("Worker thread panicked");
+ }
+ }
+}
+
+/// The worker thread used in [EventLoop] that executes incmoing tasks on the event loop's executor.
+fn worker_thread(receiver: channel::Receiver>, executor: Arc)
+where
+ T: Send,
+ E: MainThreadExecutor,
+{
+ loop {
+ match receiver.recv() {
+ Ok(Message::Task(task)) => executor.execute(task),
+ Ok(Message::Shutdown) => return,
+ Err(err) => {
+ nih_log!(
+ "Worker thread got disconnected unexpectedly, shutting down: {}",
+ err
+ );
+ return;
+ }
+ }
+ }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 698f4ce6..d163b628 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -16,6 +16,10 @@
// TODO: Once everything is more fleshed out, document the basic usage of this library
+// FIXME: Find an alternative for this
+#![feature(thread_spawn_unchecked)]
+
+pub mod context;
#[macro_use]
pub mod debug;
pub mod formatters;