executor: add "task metadata" concept, make name a task metadata.

1 files changed, 55 insertions, 1 deletions

diff --git a/embassy-executor/src/metadata.rs b/embassy-executor/src/metadata.rs
index 957417f6b..f92c9b37c 100644
--- a/embassy-executor/src/metadata.rs
+++ b/embassy-executor/src/metadata.rs
@@ -1 +1,55 @@
-pub struct Metadata {}
+#[cfg(feature = "metadata-name")]
+use core::cell::Cell;
+use core::future::{poll_fn, Future};
+use core::task::Poll;
+
+#[cfg(feature = "metadata-name")]
+use critical_section::Mutex;
+
+use crate::raw;
+
+/// Metadata associated with a task.
+pub struct Metadata {
+    #[cfg(feature = "metadata-name")]
+    name: Mutex<Cell<Option<&'static str>>>,
+}
+
+impl Metadata {
+    pub(crate) const fn new() -> Self {
+        Self {
+            #[cfg(feature = "metadata-name")]
+            name: Mutex::new(Cell::new(None)),
+        }
+    }
+
+    pub(crate) fn reset(&self) {
+        #[cfg(feature = "metadata-name")]
+        critical_section::with(|cs| self.name.borrow(cs).set(None));
+    }
+
+    /// Get the metadata for the current task.
+    ///
+    /// You can use this to read or modify the current task's metadata.
+    ///
+    /// This function is `async` just to get access to the current async
+    /// context. It returns instantly, it does not block/yield.
+    pub fn for_current_task() -> impl Future<Output = &'static Self> {
+        poll_fn(|cx| Poll::Ready(raw::task_from_waker(cx.waker()).metadata()))
+    }
+
+    /// Get this task's name
+    ///
+    /// NOTE: this takes a critical section.
+    #[cfg(feature = "metadata-name")]
+    pub fn name(&self) -> Option<&'static str> {
+        critical_section::with(|cs| self.name.borrow(cs).get())
+    }
+
+    /// Set this task's name
+    ///
+    /// NOTE: this takes a critical section.
+    #[cfg(feature = "metadata-name")]
+    pub fn set_name(&self, name: &'static str) {
+        critical_section::with(|cs| self.name.borrow(cs).set(Some(name)))
+    }
+}