Switched realtime update feed from JSON to Protobuf.

src/gtfs/realtime.rs

@@ -28,8 +28,13 @@ impl Gtfs<'_> {
         }
 
         // Parse response
-        let realtime_info: gtfs_realtime::FeedMessage  
-            = serde_json::from_reader(response)?;
+        let response_bytes= response.bytes()?;
+        let data: Result<gtfs_realtime::FeedMessage, prost::DecodeError> = prost::Message::decode(response_bytes.as_ref());
+        if data.is_err() {
+            return Err(Error {  
+                _message : format! ("Error loading realtime prtobuf: {:#?}", data.err().unwrap())
+            })
+        }
 
 
         // Build a map of (trip, stop) -> Arrival for faster lookup
@@ -41,7 +46,9 @@ impl Gtfs<'_> {
         }
 
         // Match deltas to existing arrivals
-        for entity  in realtime_info.entity {
+        let entities = data.unwrap().entity;
+        debug!("Loaded {} entities from realtime update.", entities.len());
+        for entity  in entities {
             if entity.trip_update.is_some() && entity.stop.is_some() {
                 let trip_update = entity.trip_update.unwrap();