clarify that queue length need not be precise

src/indexer/player.rs

@@ -68,7 +68,7 @@ impl PlayerIndexerStub {
     }
 
     pub fn num_indexing(&self) -> usize {
-        self.queue.len()
+        self.queue.estimate_len()
     }
 
     pub fn preceding_tickets(&self, ticket: &Ticket) -> u64 {

src/indexer/player_queue.rs

@@ -22,7 +22,7 @@ impl<T: Eq + Hash + Clone> Queue<T> {
         }
     }
 
-    pub fn len(&self) -> usize {
+    pub fn estimate_len(&self) -> usize {
         self.state.lock().unwrap().len()
     }