Fix potential memory leak

src/send.rs

@@ -118,6 +118,9 @@ impl SendQueuePriority {
 				let order_vec = self.order.get_mut(&stream).unwrap();
 				let j = order_vec.iter().position(|x| *x == order).unwrap();
 				order_vec.remove(j).unwrap();
+				if order_vec.is_empty() {
+					self.order.remove(&stream);
+				}
 			}
 		}
 	}
@@ -147,14 +150,19 @@ impl SendQueuePriority {
 				item.sent += data_frame.data().len();
 
 				if eos || is_err {
+					// If item had an order tag, remove it from the corresponding ordering list
 					if let Some(OrderTag(stream, order)) = item.order_tag {
-						assert_eq!(
-							self.order.get_mut(&stream).unwrap().pop_front(),
-							Some(order)
-						)
+						let order_stream = self.order.get_mut(&stream).unwrap();
+						assert_eq!(order_stream.pop_front(), Some(order));
+						if order_stream.is_empty() {
+							self.order.remove(&stream);
 						}
+					}
+					// Remove item from sending queue
 					self.items.remove(j);
 				} else {
+					// Move item later in send queue to implement LAS scheduling
+					// (LAS = Least Attained Service)
 					for k in j..self.items.len() - 1 {
 						if self.items[k].sent >= self.items[k + 1].sent {
 							self.items.swap(k, k + 1);