Optimize tile request starting

src/io/scheduler.rs

@@ -219,11 +219,7 @@ impl IOScheduler {
     ) -> Result<(), SendError<TileRequest>> {
         let TileRequest { coords, layers } = &tile_request;
 
-        let mut missing_layers = layers.clone();
+        if !self.tile_cache.is_layers_missing(coords, layers) {
-        self.tile_cache
-            .retain_missing_layer_names(coords, &mut missing_layers);
-
-        if missing_layers.is_empty() {
             return Ok(());
         }
 

src/io/tile_cache.rs

@@ -56,4 +56,22 @@ impl TileCache {
             layers.retain(|layer| !tessellated_set.contains(layer));
         }
     }
+
+    pub fn is_layers_missing(&self, coords: &WorldTileCoords, layers: &HashSet<String>) -> bool {
+        if let Some(results) = self.index.get(coords) {
+            let tessellated_set: HashSet<&str> = results
+                .iter()
+                .map(|tessellated_layer| tessellated_layer.layer_name())
+                .collect();
+
+            for layer in layers {
+                if !tessellated_set.contains(layer.as_str()) {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+        true
+    }
 }