task_local context over context objects

- interner impls logically separate from API in orchid-base (default host interner still in base for testing)
- error reporting, logging, and a variety of other features passed down via context in extension, not yet in host to maintain library-ish profile, should consider options
- no global spawn mechanic, the host has a spawn function but extensions only get a stash for enqueuing async work in sync callbacks which is then explicitly, manually, and with strict order popped and awaited
- still deadlocks nondeterministically for some ungodly reason

orchid-api/src/binary.rs

@@ -0,0 +1,67 @@
+//! # Binary extension definition
+//!
+//! A binary extension is a DLL / shared object / dylib with a symbol called
+//! `orchid_extension_main` which accepts a single argument of type [ExtCtx].
+//! Once that is received, communication continuees through the channel with the
+//! same protocol outlined in [crate::proto]
+
+use unsync_pipe::{Reader, Writer};
+
+/// !Send !Sync owned waker
+#[repr(C)]
+pub struct OwnedWakerVT {
+	data: *const (),
+	/// `self`
+	drop: extern "C" fn(*const ()),
+	/// `&self`
+	wake: extern "C" fn(*const ()),
+}
+
+/// !Send !Sync, equivalent to `&mut Context<'a>`, hence no `drop`.
+/// When received in [FutureVT::poll], it must not outlive the call.
+#[repr(C)]
+pub struct FutureContextVT {
+	data: *const (),
+	/// `&self`
+	waker: extern "C" fn(*const ()) -> OwnedWakerVT,
+}
+
+/// ABI-stable `Poll<()>`
+#[repr(C)]
+pub enum UnitPoll {
+	Pending,
+	Ready,
+}
+
+/// ABI-stable `Pin<Box<dyn Future<Output = ()>>>`
+#[repr(C)]
+pub struct FutureVT {
+	data: *const (),
+	/// `self`
+	drop: extern "C" fn(*const ()),
+	/// `&mut self` Equivalent to [Future::poll]
+	poll: extern "C" fn(*const (), FutureContextVT) -> UnitPoll,
+}
+
+/// Owned extension context.
+///
+/// When an extension starts, this is passed to
+#[repr(C)]
+pub struct ExtensionContext {
+	data: *const (),
+	/// `self`
+	drop: extern "C" fn(*const ()),
+	/// `self` upgrade to a later version of this struct. May only be called if
+	/// none of the other elements have been used yet. If a newer version isn't
+	/// supported, the server must return null, otherwise the the return value is
+	/// a pointer to the immediate next version of this struct
+	next: extern "C" fn(*const ()) -> *const (),
+	/// `&self` Add a future to this extension's task
+	spawn: extern "C" fn(*const (), FutureVT),
+	/// serialized [crate::HostExtChannel]
+	input: Reader,
+	/// serialized [crate::ExtHostChannel]
+	output: Writer,
+	/// UTF-8 log stream directly to log service.
+	log: Writer,
+}