cache 24hr coverage in 5min ranges, heatmap perf

Author: jackharrhy

src/where_the_plow/routes.py

@@ -42,6 +42,40 @@ def is_limited(self, key: str) -> bool:
 )  # 6 searches per min per IP
 
 
+# ── In-memory coverage cache for recent (non-historical) queries ──────
+
+_COVERAGE_TTL = 5 * 60  # 5 minutes — matches frontend rounding interval
+_COVERAGE_MAX = 20  # max entries before evicting oldest
+
+# key = (since_iso, until_iso, source|None)  ->  (expires_at_monotonic, trails)
+_coverage_cache: dict[tuple, tuple[float, list[dict]]] = {}
+
+
+def _coverage_cache_get(
+    since: datetime, until: datetime, source: str | None
+) -> list[dict] | None:
+    key = (since.isoformat(), until.isoformat(), source)
+    entry = _coverage_cache.get(key)
+    if entry is None:
+        return None
+    expires_at, trails = entry
+    if time.monotonic() > expires_at:
+        del _coverage_cache[key]
+        return None
+    return trails
+
+
+def _coverage_cache_put(
+    since: datetime, until: datetime, source: str | None, trails: list[dict]
+) -> None:
+    key = (since.isoformat(), until.isoformat(), source)
+    # Evict oldest if full
+    if len(_coverage_cache) >= _COVERAGE_MAX and key not in _coverage_cache:
+        oldest_key = min(_coverage_cache, key=lambda k: _coverage_cache[k][0])
+        del _coverage_cache[oldest_key]
+    _coverage_cache[key] = (time.monotonic() + _COVERAGE_TTL, trails)
+
+
 # ── Nominatim search proxy with in-memory cache ──────
 
 NOMINATIM_URL = "https://nominatim.openstreetmap.org/search"
@@ -334,16 +368,21 @@ def get_coverage(
     if until is None:
         until = now
 
-    # Check file cache (only hits for fully-historical queries without source filter)
-    if source is None:
-        cached = cache.get(since, until)
-        if cached is not None:
-            trails = cached
-        else:
-            trails = db.get_coverage_trails(since=since, until=until)
-            cache.put(since, until, trails)
-    else:
-        trails = db.get_coverage_trails(since=since, until=until, source=source)
+    # 1. In-memory cache (short TTL, works for recent/live queries)
+    trails = _coverage_cache_get(since, until, source)
+    if trails is None:
+        # 2. File cache (historical queries only, no source filter)
+        if source is None:
+            trails = cache.get(since, until)
+        if trails is None:
+            trails = db.get_coverage_trails(
+                since=since, until=until, **({"source": source} if source else {})
+            )
+            # Populate file cache for historical queries
+            if source is None:
+                cache.put(since, until, trails)
+        # Populate in-memory cache for all queries
+        _coverage_cache_put(since, until, source, trails)
 
     features = [
         CoverageFeature(

src/where_the_plow/static/app.js

@@ -724,6 +724,12 @@ plowMap.on("moveend", () => {
 /* ── Utilities ─────────────────────────────────────── */
 
 const ONE_DAY_MS = 24 * 60 * 60 * 1000;
+const FIVE_MIN_MS = 5 * 60 * 1000;
+
+/** Round a Date down to the nearest 5-minute boundary. */
+function floorTo5Min(date) {
+  return new Date(Math.floor(date.getTime() / FIVE_MIN_MS) * FIVE_MIN_MS);
+}
 const VEHICLE_STALE_MS = 2 * 60 * 60 * 1000; // hide vehicles not seen in 2 hours
 const SOURCE_STALE_MS = 30 * 60 * 1000; // warn if source has no data in 30 minutes
 
@@ -1433,6 +1439,10 @@ class PlowApp {
     this.stopPlayback();
     const signal = this.map.newCoverageSignal();
 
+    // Round to 5-minute boundaries so repeat loads hit the backend cache
+    since = floorTo5Min(since);
+    until = floorTo5Min(until);
+
     this.coverageSince = since;
     this.coverageUntil = until;
     this.updateRangeLabel();
@@ -1474,8 +1484,10 @@ class PlowApp {
 
   async loadCoverageForDate(dateStr) {
     const start = new Date(dateStr + "T00:00:00");
-    const end = new Date(dateStr + "T23:59:59");
-    await this.loadCoverageForRange(start, end);
+    // Use next day midnight so the 5-min floor still covers the full day
+    const nextDay = new Date(start);
+    nextDay.setDate(nextDay.getDate() + 1);
+    await this.loadCoverageForRange(start, nextDay);
   }
 
   switchCoverageView(view) {
@@ -1587,6 +1599,8 @@ class PlowApp {
           [249, 115, 22],
           [239, 68, 68],
         ],
+        weightsTextureSize: 512,
+        debounceTimeout: 100,
       }),
     ]);
   }