feat: Add configurable stats_store_interval for stats file saves

Add stats_store_interval config option to control how frequently
the statsstore.json file is written to disk. Default remains 10
seconds for backward compatibility.

This allows reducing disk I/O in production deployments and
can help avoid potential file corruption issues when external
processes read the stats file.

aprsd/conf/common.py

@@ -133,6 +133,12 @@ aprsd_opts = [
         help='Enable the Callsign seen list tracking feature.  This allows aprsd to keep track of '
         'callsigns that have been seen and when they were last seen.',
     ),
+    cfg.IntOpt(
+        'stats_store_interval',
+        default=10,
+        help='Interval in seconds between stats file saves to disk. '
+        'Lower values provide more frequent updates but increase disk I/O.',
+    ),
     cfg.BoolOpt(
         'enable_packet_logging',
         default=True,

aprsd/threads/stats.py

@@ -32,10 +32,11 @@ class APRSDStatsStoreThread(APRSDThread):
     """Save APRSD Stats to disk periodically."""
 
     daemon = False
-    period = 10
 
     def __init__(self):
         super().__init__('StatsStore')
+        # Use config value for period, default to 10 seconds
+        self.period = CONF.stats_store_interval
 
     def loop(self):
         stats = collector.Collector().collect()

tests/threads/test_stats.py

@@ -72,11 +72,20 @@ class TestAPRSDStatsStoreThread(unittest.TestCase):
 
     def test_init(self):
         """Test APRSDStatsStoreThread initialization."""
-        thread = APRSDStatsStoreThread()
-        self.assertEqual(thread.name, 'StatsStore')
-        self.assertEqual(thread.period, 10)
-        self.assertFalse(thread.daemon)
-        self.assertTrue(hasattr(thread, 'loop_count'))
+        with mock.patch('aprsd.threads.stats.CONF') as mock_conf:
+            mock_conf.stats_store_interval = 10
+            thread = APRSDStatsStoreThread()
+            self.assertEqual(thread.name, 'StatsStore')
+            self.assertEqual(thread.period, 10)
+            self.assertFalse(thread.daemon)
+            self.assertTrue(hasattr(thread, 'loop_count'))
+
+    def test_init_with_custom_interval(self):
+        """Test APRSDStatsStoreThread uses stats_store_interval from config."""
+        with mock.patch('aprsd.threads.stats.CONF') as mock_conf:
+            mock_conf.stats_store_interval = 60
+            thread = APRSDStatsStoreThread()
+            self.assertEqual(thread.period, 60)
 
     def test_loop_with_save(self):
         """Test loop method saves stats every call."""