perf(scanner): stop redoing everything on every advertisement, plus map point events

Yes, the scanner was duplicating. refreshCategoryOptions(),
updateRadar() and pairedAdapter.notifyDataSetChanged() ran from
acceptSignal on every advertisement AND from pruneTask once a second
- the same three calls either way.

Worse, the whole persist path ran per advertisement, and ScanCallback
is delivered on the main looper: a hex dump of the advertisement,
lookupCompany(), get(), lookupOui(), then telemetry(),
setDetectedCategory(), recordObservation() and setVendor(). Eight
database operations on the UI thread per beacon, at
SCAN_MODE_LOW_LATENCY, times every transmitter in range. The radar
sweep re-posts itself every 33ms and was competing for that thread,
which is why it dragged.

A device already on the radar now only gets its RSSI and last-seen
stamp refreshed until PERSIST_INTERVAL_MS (3s) is up. A device's
first sighting still takes the full path and refreshes at once.

The radar view also allocated per frame at 30fps: a six-stop
RadialGradient plus two arrays, and a fresh ArrayList and Comparator
for the target sort. Both reused now. setTargets no longer
invalidates while scanning, since onDraw already re-posts itself.
Left setLayerType(SOFTWARE) alone - setShadowLayer only works on text
under hardware acceleration, so removing it would drop the ring glow.

Separately, history points now say why they exist. location_history
had no event column, so schema 16 adds one; connected() and
disconnected() stamp it and a plain position refresh leaves it null.
The popup shows a linked or broken-link line for the two states and
stays quiet for older rows that predate the column.

History points also render as the device's own marker at half size
rather than a plain circle, sharing one divIcon per device so a long
trail does not build a DOM node per point.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

app/src/main/java/com/wytehat/btlogger/BluetoothRadarView.java

@@ -39,6 +39,18 @@ public class BluetoothRadarView extends View {
     private float zoom = 1.0f;
     private boolean suppressTap;
     private double sweepAngle = -90.0;
+
+    /* Draw-time scratch, reused every frame -- see onDraw. */
+    private android.graphics.RadialGradient glow;
+    private float glowCx = -1f, glowCy = -1f, glowR = -1f;
+    private final ArrayList<Target> ordered = new ArrayList<Target>();
+    private final Comparator<Target> byAngle = new Comparator<Target>() {
+        public int compare(Target first, Target second) {
+            float a = angleFor(first.address);
+            float b = angleFor(second.address);
+            return a < b ? -1 : (a > b ? 1 : 0);
+        }
+    };
     public BluetoothRadarView(Context context) {
         super(context);
         scaleDetector = new ScaleGestureDetector(context, new ScaleGestureDetector.SimpleOnScaleGestureListener() {
@@ -68,7 +80,10 @@ public class BluetoothRadarView extends View {
             if (!targetAngles.containsKey(target.address))
                 targetAngles.put(target.address, Float.valueOf(findOpenAngle(target.address)));
         }
-        targets.clear(); targets.addAll(values); invalidate();
+        targets.clear(); targets.addAll(values);
+        // While scanning, onDraw already re-posts itself every 33ms; an
+        // extra invalidate per update just forces redundant frames.
+        if (!scanning) invalidate();
     }
 
     protected synchronized void onDraw(Canvas canvas) {
@@ -81,9 +96,15 @@ public class BluetoothRadarView extends View {
         float glowRadius = radius + 34f;
         float edgeStop = radius / glowRadius;
         paint.setStyle(Paint.Style.FILL);
-        paint.setShader(new android.graphics.RadialGradient(cx, cy, glowRadius,
+        // Rebuilt only when the geometry moves. This used to allocate a
+        // six-stop gradient and two arrays on every frame of a 30fps sweep.
+        if (glow == null || glowCx != cx || glowCy != cy || glowR != glowRadius) {
+            glow = new android.graphics.RadialGradient(cx, cy, glowRadius,
                 new int[] { Color.TRANSPARENT, Color.argb(5, 35, 180, 110), Color.argb(24, 45, 225, 140), Color.argb(48, 55, 235, 150), Color.argb(18, 35, 190, 120), Color.TRANSPARENT },
-            new float[] { 0f, 0.55f, edgeStop - 0.05f, edgeStop, edgeStop + 0.10f, 1f }, android.graphics.Shader.TileMode.CLAMP));
+                new float[] { 0f, 0.55f, edgeStop - 0.05f, edgeStop, edgeStop + 0.10f, 1f }, android.graphics.Shader.TileMode.CLAMP);
+            glowCx = cx; glowCy = cy; glowR = glowRadius;
+        }
+        paint.setShader(glow);
         canvas.drawCircle(cx, cy, glowRadius, paint);
         paint.setShader(null);
         paint.setStyle(Paint.Style.STROKE);
@@ -123,14 +144,11 @@ public class BluetoothRadarView extends View {
         paint.setTextAlign(Paint.Align.CENTER);
         paint.setTextSize(12 * getResources().getDisplayMetrics().scaledDensity);
         canvas.drawText("YOU", cx, cy + 24, paint);
-        ArrayList<Target> ordered = new ArrayList<Target>(targets);
+        // Reused across frames; a fresh list and comparator per frame is
-        Collections.sort(ordered, new Comparator<Target>() {
+        // pure garbage at 30fps.
-            public int compare(Target first, Target second) {
+        ordered.clear();
-                float a = angleFor(first.address);
+        ordered.addAll(targets);
-                float b = angleFor(second.address);
+        Collections.sort(ordered, byAngle);
-                return a < b ? -1 : (a > b ? 1 : 0);
-            }
-        });
         float density = getResources().getDisplayMetrics().scaledDensity;
         for (int i = 0; i < ordered.size(); i++) {
             Target target = ordered.get(i);

app/src/main/java/com/wytehat/btlogger/DeviceManagerActivity.java

@@ -41,6 +41,7 @@ import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -71,6 +72,10 @@ public class DeviceManagerActivity extends Activity {
     private TextView pairedHeader;
     private ListView pairedList;
     private final Handler handler = new Handler();
+
+    /** How long one device may re-advertise before it is persisted again. */
+    private static final long PERSIST_INTERVAL_MS = 3000L;
+    private final HashMap<String, Long> lastPersisted = new HashMap<String, Long>();
     private final LinkedHashMap<String, SignalEntry> signals =
         new LinkedHashMap<String, SignalEntry>();
     private final ArrayList<BluetoothDevice> paired = new ArrayList<BluetoothDevice>();
@@ -282,7 +287,7 @@ public class DeviceManagerActivity extends Activity {
             if (!bluetooth.isEnabled()) {
                 startActivity(new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE)); return;
             }
-            stopScan(); signals.clear(); refreshCategoryOptions(); scanning = true; radar.setScanning(true); scanButton.setText("STOP RADAR SCAN"); updateRadar();
+            stopScan(); signals.clear(); lastPersisted.clear(); refreshCategoryOptions(); scanning = true; radar.setScanning(true); scanButton.setText("STOP RADAR SCAN"); updateRadar();
             scanStatus.setText("Scanning… tap a dot when your item appears");
             if (Build.VERSION.SDK_INT >= 21) {
                 leScanner = bluetooth.getBluetoothLeScanner();
@@ -312,6 +317,7 @@ public class DeviceManagerActivity extends Activity {
 
 	private void acceptScanResult(ScanResult result) {
         if (result == null) return;
+        if (touchOnly(result.getDevice(), result.getRssi())) return;
         String advertisedName = null;
         String companyVendor = null;
         int appearance = -1;
@@ -355,14 +361,40 @@ public class DeviceManagerActivity extends Activity {
         acceptSignal(device, rssi, null, null, -1, null, -1, null);
     }
 
+    /**
+     * SCAN_MODE_LOW_LATENCY hands back the same beacon many times a second,
+     * and the ScanCallback is delivered on the main looper. Running the full
+     * path for each one put two SQLite reads, four writes, a hex dump of the
+     * advertisement and a spinner rebuild on the UI thread per advertisement
+     * - which is what starves the radar sweep.
+     *
+     * A device already on screen only needs its signal strength and its
+     * last-seen stamp refreshed until the interval is up. Returns true when
+     * the caller can stop there.
+     */
+    private synchronized boolean touchOnly(BluetoothDevice device, int rssi) {
+        if (device == null || rssi == 0 || rssi == 127) return false;
+        String address = safeAddress(device);
+        SignalEntry entry = signals.get(address);
+        if (entry == null) return false;
+        Long last = lastPersisted.get(address);
+        long now = System.currentTimeMillis();
+        if (last == null || now - last.longValue() >= PERSIST_INTERVAL_MS) return false;
+        entry.rssi = rssi;
+        entry.seenAt = now;
+        return true;
+    }
+
     private synchronized void acceptSignal(BluetoothDevice device, int rssi, String advertisedName,
                                            String companyVendor, int appearance, String broadcastType,
                                            int companyId, String advertisementHex) {
         if (device == null || rssi == 0 || rssi == 127) return;
         String address = safeAddress(device);
         SignalEntry entry = signals.get(address);
-        if (entry == null) { entry = new SignalEntry(); signals.put(address, entry); }
+        boolean firstSighting = entry == null;
+        if (firstSighting) { entry = new SignalEntry(); signals.put(address, entry); }
         entry.device = device; entry.rssi = rssi; entry.seenAt = System.currentTimeMillis();
+        lastPersisted.put(address, Long.valueOf(entry.seenAt));
         String cachedName = safeName(device);
         if (useful(advertisedName)) entry.broadcastName = advertisedName;
         else if (!useful(entry.broadcastName) && useful(cachedName)) entry.broadcastName = cachedName;
@@ -381,10 +413,15 @@ public class DeviceManagerActivity extends Activity {
 								   entry.vendorName, entry.category, entry.broadcastType, appearance, companyId, advertisementHex, recentObservationFix());
         String vendor = entry.vendorName;
         if (vendor != null) database.setVendor(address, vendor);
+        // pruneTask already runs exactly these three every second while a
+        // scan is live, so doing them per advertisement was duplicated work.
+        // A device the user has not seen yet still refreshes immediately.
+        if (firstSighting) {
             runOnUiThread(new Runnable() {
 					public void run() { refreshCategoryOptions(); updateRadar(); pairedAdapter.notifyDataSetChanged(); }
 				});
         }
+    }
 
     private TrackerDatabase.Fix recentObservationFix() {
         long now = System.currentTimeMillis();
@@ -412,7 +449,10 @@ public class DeviceManagerActivity extends Activity {
             synchronized (DeviceManagerActivity.this) {
                 for (Map.Entry<String, SignalEntry> item : signals.entrySet())
                     if (item.getValue().seenAt < cutoff) expired.add(item.getKey());
-                for (int i = 0; i < expired.size(); i++) signals.remove(expired.get(i));
+                for (int i = 0; i < expired.size(); i++) {
+                    signals.remove(expired.get(i));
+                    lastPersisted.remove(expired.get(i));
+                }
                 if (selectedSignal != null && !signals.containsValue(selectedSignal)) {
                     selectedSignal = null; radarActions.setVisibility(View.GONE);
                 }

app/src/main/java/com/wytehat/btlogger/LocationPoint.java

@@ -1,8 +1,22 @@
 package com.wytehat.btlogger;
 
 public class LocationPoint {
+
+    /** The item linked to the phone at this position. */
+    public static final String EVENT_CONNECTED = "connected";
+
+    /** The link to the phone dropped at this position. */
+    public static final String EVENT_DISCONNECTED = "disconnected";
+
     public double latitude;
     public double longitude;
     public float accuracy;
     public long timestamp;
+
+    /**
+     * Why this point was recorded: EVENT_CONNECTED, EVENT_DISCONNECTED, or
+     * null for a plain position refresh while the link state was unchanged.
+     * Null for every row logged before the column existed.
+     */
+    public String event;
 }

app/src/main/java/com/wytehat/btlogger/MapHtmlBuilder.java

@@ -34,9 +34,31 @@ public final class MapHtmlBuilder {
         public int aggressiveness = HistoryNormalizer.DEFAULT_AGGRESSIVENESS;
     }
 
+    /** Diameter of a device's own marker; history points draw at half. */
+    private static final int DEVICE_MARKER_SIZE = 22;
+
+    /** A location-locked device draws smaller, since its position is fixed. */
+    private static final int LOCKED_MARKER_SIZE = 10;
+
     private MapHtmlBuilder() {
     }
 
+    /** The round white-bordered marker, shared by devices and history points. */
+    private static String divIcon(
+            String color,
+            int markerSize,
+            int iconSize,
+            int anchor) {
+
+        return "L.divIcon({className:'',html:\""
+            + "<div style='width:" + markerSize
+            + "px;height:" + markerSize
+            + "px;border-radius:50%;background:" + color
+            + ";border:2px solid white;box-shadow:0 1px 4px #333'>"
+            + "</div>\",iconSize:[" + iconSize + "," + iconSize
+            + "],iconAnchor:[" + anchor + "," + anchor + "]})";
+    }
+
     public static String build(
             List<DeviceRecord> rows,
             String selectedAddress,
@@ -90,7 +112,7 @@ public final class MapHtmlBuilder {
                     appendTrail(script, i, history, color);
                 }
 
-                appendHistoryPoints(script, record, history, color, options);
+                appendHistoryPoints(script, i, record, history, color, options);
             }
 
             appendDeviceMarker(
@@ -206,26 +228,39 @@ public final class MapHtmlBuilder {
 
     private static void appendHistoryPoints(
             StringBuilder script,
+            int index,
             DeviceRecord record,
             List<LocationPoint> history,
             String color,
             Options options) {
 
+        /*
+         * Same marker the device itself uses, at half size. Defined once per
+         * device and shared by all of its history points -- a divIcon is a
+         * DOM node per marker, so building one per point would be costly on
+         * a long trail.
+         */
+        int markerSize = DEVICE_MARKER_SIZE / 2;
+        int iconSize = markerSize + 6;
+        int anchor = iconSize / 2;
+
+        script.append("var hicon").append(index).append('=')
+            .append(divIcon(color, markerSize, iconSize, anchor))
+            .append(';');
+
         for (int p = 0; p < history.size(); p++) {
 
             LocationPoint point = history.get(p);
 
             if (point == null) continue;
 
-            script.append("L.circleMarker([")
+            script.append("L.marker([")
                 .append(point.latitude)
                 .append(',')
                 .append(point.longitude)
-                .append("],{radius:5,color:'")
+                .append("],{icon:hicon")
-                .append(color)
+                .append(index)
-                .append("',fillColor:'")
+                .append("})")
-                .append(color)
-                .append("',fillOpacity:.9,weight:2})")
                 .append(".addTo(map).bindPopup('")
                 .append(MapFormat.js(historyPopup(record, point, options)))
                 .append("');");
@@ -245,30 +280,18 @@ public final class MapHtmlBuilder {
 
         boolean locked = record.locationLocked == 1;
 
-        int markerSize = locked ? 10 : 22;
+        int markerSize = locked
+            ? LOCKED_MARKER_SIZE
+            : DEVICE_MARKER_SIZE;
+
         int iconSize = markerSize + 6;
         int anchor = iconSize / 2;
 
         String markerColor = locked ? "#00A86B" : color;
 
-        script.append("var icon").append(index)
+        script.append("var icon").append(index).append('=')
-            .append("=L.divIcon({className:'',html:\"")
+            .append(divIcon(markerColor, markerSize, iconSize, anchor))
-            .append("<div style='width:")
+            .append(';');
-            .append(markerSize)
-            .append("px;height:")
-            .append(markerSize)
-            .append("px;border-radius:50%;background:")
-            .append(markerColor)
-            .append(";border:2px solid white;box-shadow:0 1px 4px #333'>")
-            .append("</div>\",iconSize:[")
-            .append(iconSize)
-            .append(',')
-            .append(iconSize)
-            .append("],iconAnchor:[")
-            .append(anchor)
-            .append(',')
-            .append(anchor)
-            .append("]});");
 
         script.append("var marker").append(index)
             .append("=L.marker([")
@@ -492,6 +515,20 @@ public final class MapHtmlBuilder {
                     : "Previous recorded point")
             .append("</b>");
 
+        /*
+         * Why the point exists at all. Rows logged before the event column
+         * was added carry no event, and a plain position refresh carries
+         * none either, so say nothing rather than guess.
+         */
+        if (LocationPoint.EVENT_CONNECTED.equals(point.event)) {
+
+            html.append("<br>🔗 Connected to the phone here");
+
+        } else if (LocationPoint.EVENT_DISCONNECTED.equals(point.event)) {
+
+            html.append("<br>💔 Link to the phone dropped here");
+        }
+
         long time = HistoryNormalizer.pointTime(point);
 
         if (time > 0) {

app/src/main/java/com/wytehat/btlogger/TrackerDatabase.java

@@ -11,7 +11,7 @@ import java.util.Locale;
 
 public class TrackerDatabase extends SQLiteOpenHelper {
     private static final String DB_NAME = "bluetooth_tracker.db";
-    private static final int DB_VERSION = 15;
+    private static final int DB_VERSION = 16;
 
     public TrackerDatabase(Context context) {
         super(context, DB_NAME, null, DB_VERSION);
@@ -32,6 +32,7 @@ public class TrackerDatabase extends SQLiteOpenHelper {
 				point.longitude = cursor.getDouble(cursor.getColumnIndex("longitude"));
 				point.accuracy = cursor.getFloat(cursor.getColumnIndex("accuracy"));
 				point.timestamp = cursor.getLong(cursor.getColumnIndex("logged_at"));
+				point.event = cursor.getString(cursor.getColumnIndex("event"));
 				result.add(point);
 			}
 		} finally { cursor.close(); }
@@ -100,6 +101,8 @@ public class TrackerDatabase extends SQLiteOpenHelper {
             addColumn(db, "ALTER TABLE devices ADD COLUMN track_broadcast INTEGER DEFAULT 0");
         if (oldVersion < 14) createSupportingTables(db);
         if (oldVersion < 15) seedVendors(db);
+        if (oldVersion < 16)
+            addColumn(db, "ALTER TABLE location_history ADD COLUMN event TEXT");
     }
 
     private void addColumn(SQLiteDatabase db, String sql) {
@@ -108,7 +111,7 @@ public class TrackerDatabase extends SQLiteOpenHelper {
 
     private void createSupportingTables(SQLiteDatabase db) {
         db.execSQL("CREATE TABLE IF NOT EXISTS location_history (id INTEGER PRIMARY KEY AUTOINCREMENT," +
-            "address TEXT,latitude REAL,longitude REAL,accuracy REAL,logged_at INTEGER)");
+            "address TEXT,latitude REAL,longitude REAL,accuracy REAL,logged_at INTEGER,event TEXT)");
         db.execSQL("CREATE INDEX IF NOT EXISTS history_address_time ON location_history(address,logged_at)");
         db.execSQL("CREATE TABLE IF NOT EXISTS range_samples (id INTEGER PRIMARY KEY AUTOINCREMENT," +
             "address TEXT,session_id TEXT,sampled_at INTEGER,latitude REAL,longitude REAL," +
@@ -166,7 +169,8 @@ public class TrackerDatabase extends SQLiteOpenHelper {
         if (old != null) preserveProfile(values, old, fix);
         getWritableDatabase().insertWithOnConflict("devices", null, values,
             SQLiteDatabase.CONFLICT_REPLACE);
-        if (fix != null) insertHistory(address, fix, time);
+        if (fix != null)
+            insertHistory(address, fix, time, LocationPoint.EVENT_CONNECTED);
     }
 
     public synchronized void disconnected(String address, String broadcast, long time,
@@ -177,7 +181,8 @@ public class TrackerDatabase extends SQLiteOpenHelper {
         values.put("reason", reason);
         values.put("is_tracked", 1);
         getWritableDatabase().update("devices", values, "address=?", new String[] { address });
-        if (fix != null) insertHistory(address, fix, time);
+        if (fix != null)
+            insertHistory(address, fix, time, LocationPoint.EVENT_DISCONNECTED);
     }
 
     public synchronized void telemetry(String address, String broadcast, Integer battery,
@@ -242,16 +247,21 @@ public class TrackerDatabase extends SQLiteOpenHelper {
         values.put("has_location", 1);
         values.put("updated_at", time);
         getWritableDatabase().update("devices", values, "address=?", new String[] { address });
-        insertHistory(address, fix, time);
+        insertHistory(address, fix, time, null);
     }
 
-    private void insertHistory(String address, Fix fix, long time) {
+    /**
+     * @param event LocationPoint.EVENT_CONNECTED or EVENT_DISCONNECTED for a
+     *              link state change, null for a plain position refresh.
+     */
+    private void insertHistory(String address, Fix fix, long time, String event) {
         ContentValues values = new ContentValues();
         values.put("address", address);
         values.put("latitude", fix.latitude);
         values.put("longitude", fix.longitude);
         values.put("accuracy", fix.accuracy);
         values.put("logged_at", time);
+        values.put("event", event);
         getWritableDatabase().insert("location_history", null, values);
     }
 
@@ -437,6 +447,7 @@ public class TrackerDatabase extends SQLiteOpenHelper {
                 point.longitude = cursor.getDouble(cursor.getColumnIndex("longitude"));
                 point.accuracy = cursor.getFloat(cursor.getColumnIndex("accuracy"));
                 point.timestamp = cursor.getLong(cursor.getColumnIndex("logged_at"));
+				point.event = cursor.getString(cursor.getColumnIndex("event"));
                 result.add(point);
             }
         } finally { cursor.close(); }