1 files changed, 26 insertions, 0 deletions
diff --git a/tokio-util/src/time/wheel/stack.rs b/tokio-util/src/time/wheel/stack.rs
new file mode 100644
index 00000000..6e55c38c
--- /dev/null
+++ b/tokio-util/src/time/wheel/stack.rs
@@ -0,0 +1,26 @@
+use std::borrow::Borrow;
+
+/// Abstracts the stack operations needed to track timeouts.
+pub(crate) trait Stack: Default {
+    /// Type of the item stored in the stack
+    type Owned: Borrow<Self::Borrowed>;
+
+    /// Borrowed item
+    type Borrowed;
+
+    /// Item storage, this allows a slab to be used instead of just the heap
+    type Store;
+
+    /// Returns `true` if the stack is empty
+    fn is_empty(&self) -> bool;
+
+    /// Push an item onto the stack
+    fn push(&mut self, item: Self::Owned, store: &mut Self::Store);
+
+    /// Pop an item from the stack
+    fn pop(&mut self, store: &mut Self::Store) -> Option<Self::Owned>;
+
+    fn remove(&mut self, item: &Self::Borrowed, store: &mut Self::Store);
+
+    fn when(item: &Self::Borrowed, store: &Self::Store) -> u64;
+}