pop front for queue?

distaff/src/queue.rs

@@ -90,6 +90,22 @@ impl<T> Slot<T> {
             })
     }
 
+    /// this operation isn't atomic.
+    unsafe fn pop_front(&self) -> Option<T> {
+        // SAFETY: The caller must ensure that they have exclusive access to the slot
+        if self.is_set() {
+            let next = self.next_ptr();
+            unsafe { (next.as_ref()).pop_front() }
+        } else {
+            // SAFETY: The value is only initialized when the state is set to 1.
+            if self.next_and_state.tag(Ordering::Acquire) == 1 {
+                Some(unsafe { self.value.as_ref_unchecked().assume_init_read() })
+            } else {
+                None
+            }
+        }
+    }
+
     /// the caller must ensure that they have exclusive access to the slot
     unsafe fn push(&self, value: T) {
         if self.is_set() {