Add hook/event system

1 files changed, 88 insertions, 0 deletions

diff --git a/helix-event/src/runtime.rs b/helix-event/src/runtime.rs
new file mode 100644
index 00000000..8da465ef
--- /dev/null
+++ b/helix-event/src/runtime.rs
@@ -0,0 +1,88 @@
+//! The event system makes use of global to decouple different systems.
+//! However, this can cause problems for the integration test system because
+//! it runs multiple helix applications in parallel. Making the globals
+//! thread-local does not work because a applications can/does have multiple
+//! runtime threads. Instead this crate implements a similar notion to a thread
+//! local but instead of being local to a single thread, the statics are local to
+//! a single tokio-runtime. The implementation requires locking so it's not exactly efficient.
+//!
+//! Therefore this function is only enabled during integration tests and behaves like
+//! a normal static otherwise. I would prefer this module to be fully private and to only
+//! export the macro but the macro still need to construct these internals so it's marked
+//! `doc(hidden)` instead
+
+use std::ops::Deref;
+
+#[cfg(not(feature = "integration_test"))]
+pub struct RuntimeLocal<T: 'static> {
+    /// inner API used in the macro, not part of public API
+    #[doc(hidden)]
+    pub __data: T,
+}
+
+#[cfg(not(feature = "integration_test"))]
+impl<T> Deref for RuntimeLocal<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.__data
+    }
+}
+
+#[cfg(not(feature = "integration_test"))]
+#[macro_export]
+macro_rules! runtime_local {
+    ($($(#[$attr:meta])* $vis: vis static $name:ident: $ty: ty = $init: expr;)*) => {
+        $($(#[$attr])* $vis static $name: $crate::runtime::RuntimeLocal<$ty> = $crate::runtime::RuntimeLocal {
+            __data: $init
+        };)*
+    };
+}
+
+#[cfg(feature = "integration_test")]
+pub struct RuntimeLocal<T: 'static> {
+    data:
+        parking_lot::RwLock<hashbrown::HashMap<tokio::runtime::Id, &'static T, ahash::RandomState>>,
+    init: fn() -> T,
+}
+
+#[cfg(feature = "integration_test")]
+impl<T> RuntimeLocal<T> {
+    /// inner API used in the macro, not part of public API
+    #[doc(hidden)]
+    pub const fn __new(init: fn() -> T) -> Self {
+        Self {
+            data: parking_lot::RwLock::new(hashbrown::HashMap::with_hasher(
+                ahash::RandomState::with_seeds(423, 9978, 38322, 3280080),
+            )),
+            init,
+        }
+    }
+}
+
+#[cfg(feature = "integration_test")]
+impl<T> Deref for RuntimeLocal<T> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        let id = tokio::runtime::Handle::current().id();
+        let guard = self.data.read();
+        match guard.get(&id) {
+            Some(res) => res,
+            None => {
+                drop(guard);
+                let data = Box::leak(Box::new((self.init)()));
+                let mut guard = self.data.write();
+                guard.insert(id, data);
+                data
+            }
+        }
+    }
+}
+
+#[cfg(feature = "integration_test")]
+#[macro_export]
+macro_rules! runtime_local {
+    ($($(#[$attr:meta])* $vis: vis static $name:ident: $ty: ty = $init: expr;)*) => {
+         $($(#[$attr])* $vis static $name: $crate::runtime::RuntimeLocal<$ty> = $crate::runtime::RuntimeLocal::__new(|| $init);)*
+    };
+}