psud: adding led state change detection mechanism to prevent unnecessary updated to redis

sonic-psud/scripts/psud

@@ -296,6 +296,7 @@ class PsuStatus(object):
         self.check_psu_power_threshold = False
         self.power_exceeded_threshold = False
         self.logger = logger
+        self.led_status = NOT_AVAILABLE
 
     def set_presence(self, presence):
         """
@@ -358,6 +359,18 @@ class PsuStatus(object):
         self.power_exceeded_threshold = power_exceeded_threshold
         return True
 
+    def set_led_status(self, led_status):
+        """
+        Set and cache PSU LED status
+        :param led_status: PSU LED status
+        :return: True if status changed else False
+        """
+        if led_status == self.led_status:
+            return False
+
+        self.led_status = led_status
+        return True
+
     def is_ok(self):
         return self.presence and self.power_good and self.voltage_good and self.temperature_good
 
@@ -670,10 +683,13 @@ class DaemonPsud(daemon_base.DaemonBase):
             return
 
         for index, psu_status in self.psu_status_dict.items():
-            fvs = swsscommon.FieldValuePairs([
-                ('led_status', str(try_get(psu_status.psu.get_status_led, NOT_AVAILABLE)))
-            ])
-            self.psu_tbl.set(get_psu_key(index), fvs)
+            led_status = try_get(psu_status.psu.get_status_led, NOT_AVAILABLE)
+            led_status_changed = psu_status.set_led_status(led_status)
+            if led_status_changed:
+                fvs = swsscommon.FieldValuePairs([
+                    ('led_status', str(led_status))
+                ])
+                self.psu_tbl.set(get_psu_key(index), fvs)
             self._update_psu_fan_led_status(psu_status.psu, index)
 
     def _update_psu_fan_led_status(self, psu, psu_index):

sonic-psud/tests/test_DaemonPsud.py

@@ -389,6 +389,7 @@ def test_update_led_color(self):
         assert daemon_psud.psu_tbl.set.call_count == 0
         assert daemon_psud._update_psu_fan_led_status.call_count == 0
 
+        # First run: LED status is OFF, should write to DB (initial state)
         psud.platform_chassis = MockChassis()
         daemon_psud.psu_status_dict[1] = psu_status
         expected_fvp = psud.swsscommon.FieldValuePairs([('led_status', MockPsu.STATUS_LED_COLOR_OFF)])
@@ -401,6 +402,15 @@ def test_update_led_color(self):
         daemon_psud.psu_tbl.reset_mock()
         daemon_psud._update_psu_fan_led_status.reset_mock()
 
+        # Second run: LED status is still OFF, should NOT write to DB (no change)
+        daemon_psud._update_led_color()
+        assert daemon_psud.psu_tbl.set.call_count == 0
+        assert daemon_psud._update_psu_fan_led_status.call_count == 1  # Fan LED status still checked
+
+        daemon_psud.psu_tbl.reset_mock()
+        daemon_psud._update_psu_fan_led_status.reset_mock()
+
+        # LED changes from OFF to GREEN, should write to DB
         mock_psu.set_status_led(MockPsu.STATUS_LED_COLOR_GREEN)
         expected_fvp = psud.swsscommon.FieldValuePairs([('led_status', MockPsu.STATUS_LED_COLOR_GREEN)])
         daemon_psud._update_led_color()
@@ -412,6 +422,15 @@ def test_update_led_color(self):
         daemon_psud.psu_tbl.reset_mock()
         daemon_psud._update_psu_fan_led_status.reset_mock()
 
+        # LED status is still GREEN, should NOT write to DB (no change)
+        daemon_psud._update_led_color()
+        assert daemon_psud.psu_tbl.set.call_count == 0
+        assert daemon_psud._update_psu_fan_led_status.call_count == 1
+
+        daemon_psud.psu_tbl.reset_mock()
+        daemon_psud._update_psu_fan_led_status.reset_mock()
+
+        # LED changes from GREEN to RED, should write to DB
         mock_psu.set_status_led(MockPsu.STATUS_LED_COLOR_RED)
         expected_fvp = psud.swsscommon.FieldValuePairs([('led_status', MockPsu.STATUS_LED_COLOR_RED)])
         daemon_psud._update_led_color()
@@ -423,7 +442,26 @@ def test_update_led_color(self):
         daemon_psud.psu_tbl.reset_mock()
         daemon_psud._update_psu_fan_led_status.reset_mock()
 
-        # Test exception handling
+        # LED status is still RED, should NOT write to DB (no change)
+        daemon_psud._update_led_color()
+        assert daemon_psud.psu_tbl.set.call_count == 0
+        assert daemon_psud._update_psu_fan_led_status.call_count == 1
+
+        daemon_psud.psu_tbl.reset_mock()
+        daemon_psud._update_psu_fan_led_status.reset_mock()
+
+        # LED changes back from RED to GREEN, should write to DB
+        mock_psu.set_status_led(MockPsu.STATUS_LED_COLOR_GREEN)
+        expected_fvp = psud.swsscommon.FieldValuePairs([('led_status', MockPsu.STATUS_LED_COLOR_GREEN)])
+        daemon_psud._update_led_color()
+        assert daemon_psud.psu_tbl.set.call_count == 1
+        daemon_psud.psu_tbl.set.assert_called_with(psud.PSU_INFO_KEY_TEMPLATE.format(1), expected_fvp)
+        assert daemon_psud._update_psu_fan_led_status.call_count == 1
+
+        daemon_psud.psu_tbl.reset_mock()
+        daemon_psud._update_psu_fan_led_status.reset_mock()
+
+        # Test exception handling - LED status becomes N/A, should write to DB
         mock_psu.get_status_led = mock.Mock(side_effect=NotImplementedError)
         expected_fvp = psud.swsscommon.FieldValuePairs([('led_status', psud.NOT_AVAILABLE)])
         daemon_psud._update_led_color()
@@ -432,6 +470,14 @@ def test_update_led_color(self):
         assert daemon_psud._update_psu_fan_led_status.call_count == 1
         daemon_psud._update_psu_fan_led_status.assert_called_with(mock_psu, 1)
 
+        daemon_psud.psu_tbl.reset_mock()
+        daemon_psud._update_psu_fan_led_status.reset_mock()
+
+        # LED status is still N/A, should NOT write to DB (no change)
+        daemon_psud._update_led_color()
+        assert daemon_psud.psu_tbl.set.call_count == 0
+        assert daemon_psud._update_psu_fan_led_status.call_count == 1
+
     def test_update_psu_fan_led_status(self):
         mock_fan = MockFan("PSU 1 Test Fan 1", MockFan.FAN_DIRECTION_INTAKE)
         mock_psu = MockPsu("PSU 1", 0, True, True)