Morning improvements

server-rs/src/state.rs

@@ -1,5 +1,8 @@
+use std::path::PathBuf;
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 
+use parking_lot::RwLock;
 use rustc_hash::FxHashMap;
 
 use crate::auth::TokenCache;
@@ -10,16 +13,12 @@ use crate::routes::FeaturesResponse;
 use crate::utils::GridIndex;
 
 pub struct AppState {
+    // --- Rebuilt on reload ---
     pub data: PropertyData,
     pub grid: GridIndex,
     /// h3_cells[row_idx] = precomputed H3 cell ID at max resolution (12).
     /// Parent cells for lower resolutions derived via CellIndex::parent().
     pub h3_cells: Vec<u64>,
-    pub poi_data: POIData,
-    pub poi_grid: GridIndex,
-    pub place_data: PlaceData,
-    /// Postcode boundary data for high-zoom rendering
-    pub postcode_data: PostcodeData,
     /// O(1) lookup: feature name → index in feature_names/feature_data
     pub feature_name_to_index: FxHashMap<String, usize>,
     /// Precomputed JSON key names: "min_{feature_name}" for each feature
@@ -28,10 +27,25 @@ pub struct AppState {
     pub max_keys: Vec<String>,
     /// Precomputed JSON key names: "avg_{feature_name}" for each feature
     pub avg_keys: Vec<String>,
-    /// Precomputed POI category groups (sorted)
-    pub poi_category_groups: Vec<POICategoryGroup>,
     /// Precomputed features response for /api/features endpoint
     pub features_response: FeaturesResponse,
+    /// Complete system prompt for AI filters (features + examples + instructions)
+    pub ai_filters_system_prompt: String,
+
+    // --- Shared across reloads (Arc for cheap cloning) ---
+    pub poi_data: Arc<POIData>,
+    pub poi_grid: Arc<GridIndex>,
+    pub place_data: Arc<PlaceData>,
+    /// Postcode boundary data for high-zoom rendering
+    pub postcode_data: Arc<PostcodeData>,
+    /// Precomputed POI category groups (sorted)
+    pub poi_category_groups: Arc<Vec<POICategoryGroup>>,
+    /// Precomputed travel time data store
+    pub travel_time_store: Arc<TravelTimeStore>,
+    /// Token validation cache (60s TTL)
+    pub token_cache: Arc<TokenCache>,
+
+    // --- Config (cheap to clone) ---
     /// URL of the screenshot service (e.g. http://screenshot:8002)
     pub screenshot_url: String,
     /// Public-facing URL for absolute og:image URLs (e.g. https://perfectpostcodes.dev)
@@ -52,12 +66,6 @@ pub struct AppState {
     pub gemini_api_key: String,
     /// Gemini model name (e.g. gemini-2.0-flash)
     pub gemini_model: String,
-    /// Precomputed travel time data store
-    pub travel_time_store: Arc<TravelTimeStore>,
-    /// Token validation cache (60s TTL)
-    pub token_cache: Arc<TokenCache>,
-    /// Complete system prompt for AI filters (features + examples + instructions)
-    pub ai_filters_system_prompt: String,
     /// Google Maps API key for Street View metadata lookups
     pub google_maps_api_key: String,
     /// Stripe secret key for creating checkout sessions
@@ -67,3 +75,57 @@ pub struct AppState {
     /// Stripe Coupon ID for referral discounts
     pub stripe_referral_coupon_id: String,
 }
+
+/// Wraps AppState with atomic swap capability for hot-reloading.
+/// Route handlers call `load_state()` to get the current snapshot.
+/// The reload endpoint builds a new AppState and swaps it in atomically.
+pub struct SharedState {
+    current: RwLock<Arc<AppState>>,
+    reloading: AtomicBool,
+    /// Paths needed for data reload
+    pub properties_path: PathBuf,
+    pub postcode_features_path: PathBuf,
+    pub listings_buy_path: PathBuf,
+    pub listings_rent_path: PathBuf,
+}
+
+impl SharedState {
+    pub fn new(
+        state: AppState,
+        properties_path: PathBuf,
+        postcode_features_path: PathBuf,
+        listings_buy_path: PathBuf,
+        listings_rent_path: PathBuf,
+    ) -> Self {
+        Self {
+            current: RwLock::new(Arc::new(state)),
+            reloading: AtomicBool::new(false),
+            properties_path,
+            postcode_features_path,
+            listings_buy_path,
+            listings_rent_path,
+        }
+    }
+
+    /// Get the current AppState snapshot. Cheap (Arc clone under a brief read lock).
+    pub fn load_state(&self) -> Arc<AppState> {
+        self.current.read().clone()
+    }
+
+    /// Atomically swap in a new AppState. Old state is dropped when all references are gone.
+    pub fn swap_state(&self, new_state: AppState) {
+        *self.current.write() = Arc::new(new_state);
+    }
+
+    /// Try to mark reload as in-progress. Returns false if already reloading.
+    pub fn try_start_reload(&self) -> bool {
+        self.reloading
+            .compare_exchange(false, true, Ordering::Acquire, Ordering::Relaxed)
+            .is_ok()
+    }
+
+    /// Mark reload as complete.
+    pub fn finish_reload(&self) {
+        self.reloading.store(false, Ordering::Release);
+    }
+}