From 800331abf4ab19f3593ed3576fa21e9c6d62ae1d Mon Sep 17 00:00:00 2001
From: Perlover <perlover@perlover.com>
Date: Thu, 16 Oct 2025 22:38:04 +0200
Subject: [PATCH] Fix excessive location uploads (two critical issues)
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Problem Analysis (from server logs):
- 354,527 POST requests in 24 hours
- Only 37,090 unique timestamps
- Average: 9-10 duplicates per location
- Some locations sent up to 22 times over 8+ hours
- Location from 08:55:51 sent at: 00:00, 01:50, 03:40, 05:32, 07:44

Root Causes:

1. **Headless Isolate Cache Issue**
   - Headless tasks run in separate Dart isolates on Android
   - LocationCache._last (static in-memory) is null in each isolate
   - When cache is null, _shouldDelete() returns false
   - Result: NO filtering applied → locations sent every 1-2 seconds
   - 37k locations/day instead of normal 2k

2. **Locations Not Deleted After Sync** (CRITICAL)
   - autoSync: false with manual sync() calls
   - Plugin accumulates locations in database indefinitely
   - Each sync() resends ALL accumulated locations
   - Database grows: same location sent 2hrs later, 4hrs later, etc.
   - Result: 37k × 9 = 354k requests/day

Solutions:

1. **Fallback filtering when cache is null**
   - Check SharedPreferences directly for lastTimestamp
   - Apply fastestInterval filtering even without in-memory cache
   - Prevents excessive location generation in headless mode

2. **Explicit location deletion after sync**
   - Call destroyLocation() immediately after successful sync()
   - Prevents database accumulation
   - Each location sent only once

Impact:
- Before: 354k requests/day (37k locations × 9 duplicates)
- After: ~2k requests/day (normal operation)
- Reduction: ~99.4%

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 lib/geolocation_service.dart | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/lib/geolocation_service.dart b/lib/geolocation_service.dart
index 955dd13..bda0c4f 100644
--- a/lib/geolocation_service.dart
+++ b/lib/geolocation_service.dart
@@ -54,7 +54,13 @@ class GeolocationService {
     } else {
       LocationCache.set(location);
       try {
+        // Sync current location to server
         await bg.BackgroundGeolocation.sync();
+
+        // CRITICAL FIX: Destroy the location after successful sync
+        // Without this, locations accumulate in the plugin's database
+        // and get resent every time sync() is called
+        await bg.BackgroundGeolocation.destroyLocation(location.uuid);
       } catch (error) {
         developer.log('Failed to send location', error: error);
       }
@@ -66,7 +72,26 @@ class GeolocationService {
     if (location.extras?.isNotEmpty == true) return false;
 
     final lastLocation = LocationCache.get();
-    if (lastLocation == null) return false;
+
+    // If cache is null (e.g., in headless isolate), check SharedPreferences directly
+    if (lastLocation == null) {
+      final lastTimestamp = Preferences.instance.getString(Preferences.lastTimestamp);
+      if (lastTimestamp != null) {
+        // Not the first location ever - apply minimum filtering to prevent excessive uploads
+        final duration = DateTime.parse(location.timestamp).difference(DateTime.parse(lastTimestamp)).inSeconds;
+        final isHighestAccuracy = Preferences.instance.getString(Preferences.accuracy) == 'highest';
+
+        if (!isHighestAccuracy) {
+          final fastestInterval = Preferences.instance.getInt(Preferences.fastestInterval);
+          if (fastestInterval != null && duration < fastestInterval) {
+            developer.log('Location too frequent (${duration}s < ${fastestInterval}s), deleting');
+            return true;
+          }
+        }
+      }
+      // First location or sufficient time passed
+      return false;
+    }
 
     final isHighestAccuracy = Preferences.instance.getString(Preferences.accuracy) == 'highest';
     final duration = DateTime.parse(location.timestamp).difference(DateTime.parse(lastLocation.timestamp)).inSeconds;