Backpressure-driven Fairness

Co-Authored-By: brekotis <93345790+brekotis@users.noreply.github.com>

src/transport/middle_proxy/registry.rs

@@ -140,6 +140,10 @@ impl ConnRegistry {
         }
     }
 
+    pub fn route_channel_capacity(&self) -> usize {
+        self.route_channel_capacity
+    }
+
     #[cfg(test)]
     pub fn new() -> Self {
         Self::with_route_channel_capacity(4096)