1 files changed, 111 insertions, 0 deletions
diff --git a/third_party/rust/tokio/src/runtime/context.rs b/third_party/rust/tokio/src/runtime/context.rs
new file mode 100644
index 0000000000..1f44a53402
--- /dev/null
+++ b/third_party/rust/tokio/src/runtime/context.rs
@@ -0,0 +1,111 @@
+//! Thread local runtime context
+use crate::runtime::{Handle, TryCurrentError};
+
+use std::cell::RefCell;
+
+thread_local! {
+    static CONTEXT: RefCell<Option<Handle>> = RefCell::new(None)
+}
+
+pub(crate) fn try_current() -> Result<Handle, crate::runtime::TryCurrentError> {
+    match CONTEXT.try_with(|ctx| ctx.borrow().clone()) {
+        Ok(Some(handle)) => Ok(handle),
+        Ok(None) => Err(TryCurrentError::new_no_context()),
+        Err(_access_error) => Err(TryCurrentError::new_thread_local_destroyed()),
+    }
+}
+
+pub(crate) fn current() -> Handle {
+    match try_current() {
+        Ok(handle) => handle,
+        Err(e) => panic!("{}", e),
+    }
+}
+
+cfg_io_driver! {
+    pub(crate) fn io_handle() -> crate::runtime::driver::IoHandle {
+        match CONTEXT.try_with(|ctx| {
+            let ctx = ctx.borrow();
+            ctx.as_ref().expect(crate::util::error::CONTEXT_MISSING_ERROR).io_handle.clone()
+        }) {
+            Ok(io_handle) => io_handle,
+            Err(_) => panic!("{}", crate::util::error::THREAD_LOCAL_DESTROYED_ERROR),
+        }
+    }
+}
+
+cfg_signal_internal! {
+    #[cfg(unix)]
+    pub(crate) fn signal_handle() -> crate::runtime::driver::SignalHandle {
+        match CONTEXT.try_with(|ctx| {
+            let ctx = ctx.borrow();
+            ctx.as_ref().expect(crate::util::error::CONTEXT_MISSING_ERROR).signal_handle.clone()
+        }) {
+            Ok(signal_handle) => signal_handle,
+            Err(_) => panic!("{}", crate::util::error::THREAD_LOCAL_DESTROYED_ERROR),
+        }
+    }
+}
+
+cfg_time! {
+    pub(crate) fn time_handle() -> crate::runtime::driver::TimeHandle {
+        match CONTEXT.try_with(|ctx| {
+            let ctx = ctx.borrow();
+            ctx.as_ref().expect(crate::util::error::CONTEXT_MISSING_ERROR).time_handle.clone()
+        }) {
+            Ok(time_handle) => time_handle,
+            Err(_) => panic!("{}", crate::util::error::THREAD_LOCAL_DESTROYED_ERROR),
+        }
+    }
+
+    cfg_test_util! {
+        pub(crate) fn clock() -> Option<crate::runtime::driver::Clock> {
+            match CONTEXT.try_with(|ctx| (*ctx.borrow()).as_ref().map(|ctx| ctx.clock.clone())) {
+                Ok(clock) => clock,
+                Err(_) => panic!("{}", crate::util::error::THREAD_LOCAL_DESTROYED_ERROR),
+            }
+        }
+    }
+}
+
+cfg_rt! {
+    pub(crate) fn spawn_handle() -> Option<crate::runtime::Spawner> {
+        match CONTEXT.try_with(|ctx| (*ctx.borrow()).as_ref().map(|ctx| ctx.spawner.clone())) {
+            Ok(spawner) => spawner,
+            Err(_) => panic!("{}", crate::util::error::THREAD_LOCAL_DESTROYED_ERROR),
+        }
+    }
+}
+
+/// Sets this [`Handle`] as the current active [`Handle`].
+///
+/// [`Handle`]: Handle
+pub(crate) fn enter(new: Handle) -> EnterGuard {
+    match try_enter(new) {
+        Some(guard) => guard,
+        None => panic!("{}", crate::util::error::THREAD_LOCAL_DESTROYED_ERROR),
+    }
+}
+
+/// Sets this [`Handle`] as the current active [`Handle`].
+///
+/// [`Handle`]: Handle
+pub(crate) fn try_enter(new: Handle) -> Option<EnterGuard> {
+    CONTEXT
+        .try_with(|ctx| {
+            let old = ctx.borrow_mut().replace(new);
+            EnterGuard(old)
+        })
+        .ok()
+}
+
+#[derive(Debug)]
+pub(crate) struct EnterGuard(Option<Handle>);
+
+impl Drop for EnterGuard {
+    fn drop(&mut self) {
+        CONTEXT.with(|ctx| {
+            *ctx.borrow_mut() = self.0.take();
+        });
+    }
+}