[SflowMgr] SamplingRate Update by Speed Change Added (sonic-net#1721)

Currently, the SflowMgr::sflowUpdatePortInfo method updates the sampling-rate only when adding a new-port. Updated the method to be active for speed change notifications all the time.

Co-authored-by: Vivek Reddy Karri <vkarri@nvidia.com>

cfgmgr/sflowmgr.cpp

@@ -89,17 +89,26 @@ void SflowMgr::sflowUpdatePortInfo(Consumer &consumer)
                 port_info.admin = "";
                 m_sflowPortConfMap[key] = port_info;
             }
+
+            bool speed_change = false;
+            string new_speed = SFLOW_ERROR_SPEED_STR;
             for (auto i : values)
             {
                 if (fvField(i) == "speed")
                 {
-                    m_sflowPortConfMap[key].speed = fvValue(i);
+                    new_speed = fvValue(i);
                 }
             }
+            if (m_sflowPortConfMap[key].speed != new_speed)
+            {
+                m_sflowPortConfMap[key].speed = new_speed;
+                speed_change = true;
+            }
 
-            if (new_port)
+            if (m_gEnable && m_intfAllConf)
             {
-                if (m_gEnable && m_intfAllConf)
+                // If the Local Conf is already present, dont't override it even though the speed is changed
+                if (new_port || (speed_change && !m_sflowPortConfMap[key].local_conf))
                 {
                     vector<FieldValueTuple> fvs;
                     sflowGetGlobalInfo(fvs, m_sflowPortConfMap[key].speed);
@@ -171,7 +180,7 @@ void SflowMgr::sflowGetGlobalInfo(vector<FieldValueTuple> &fvs, string speed)
     FieldValueTuple fv1("admin_state", "up");
     fvs.push_back(fv1);
 
-    if (speed != SFLOW_ERROR_SPEED_STR)
+    if (speed != SFLOW_ERROR_SPEED_STR && sflowSpeedRateInitMap.find(speed) != sflowSpeedRateInitMap.end())
     {
         rate = sflowSpeedRateInitMap[speed];
     }

tests/test_sflow.py

@@ -1,3 +1,5 @@
+import time
+
 class TestSflow:
     speed_rate_table = {
         "400000": "400000",
@@ -131,6 +133,48 @@ def test_ConfigDel(self, dvs, testlog):
 
         expected_fields = {"SAI_SAMPLEPACKET_ATTR_SAMPLE_RATE": rate}
         self.adb.wait_for_field_match("ASIC_STATE:SAI_OBJECT_TYPE_SAMPLEPACKET", sample_session, expected_fields)
+
+    def test_SamplingRatePortCfgUpdate(self, dvs, testlog):
+        '''
+        This test checks if the SflowMgr updates the sampling rate 
+        1) When the Speed is Updated on the port and no local configuration has been given on the port
+        Eg:
+        config sflow enable
+        config interface speed Ethernet0  25000  (Let's suppose Original Speed for Ethernet0 is 100G)
+        show sflow interface | grep Ethernet0    (Should see a sampling rate of 25000 not 100000)
+        '''
+        self.setup_sflow(dvs)
+        appldb = dvs.get_app_db()
+        #dvs.runcmd("portconfig -p {} -s {}".format("Ethernet0", "25000"))
+        self.cdb.update_entry("PORT", "Ethernet0", {'speed' : "25000"})
+        expected_fields = {"sample_rate": self.speed_rate_table["25000"]}
+        appldb.wait_for_field_match("SFLOW_SESSION_TABLE", "Ethernet0", expected_fields)
+
+
+    def test_SamplingRateManualUpdate(self, dvs, testlog):
+        '''  
+        This test checks if the SflowMgr updates the sampling rate 
+        1) When the Cfg Sflow Table is updated with sampling rate by the user, this rate should not be impacted by Port Speed Changes
+        Eg:
+        config sflow enable
+        config sflow interface sample-rate Ethernet4 256
+        config interface Ethernet0 speed 25000  (Original Speed for Ethernet0 is 100G)
+        show sflow interface | grep Ethernet0   (Should see  a sampling rate of 256 not 100000 or 25000
+        '''
+        self.setup_sflow(dvs)
+        appldb = dvs.get_app_db()
+
+        session_params = {"admin_state": "up", "sample_rate": "256"}
+        self.cdb.create_entry("SFLOW_SESSION", "Ethernet4", session_params)
+        self.cdb.wait_for_field_match("SFLOW_SESSION", "Ethernet4", session_params)
+        appldb.wait_for_field_match("SFLOW_SESSION_TABLE", "Ethernet4", {"sample_rate": "256"})
+
+        self.cdb.update_entry("PORT", "Ethernet4", {'speed' : "25000"})
+        # The Check here is about the original value not getting changed. 
+        # If some bug was to appear, let's give it some time to get noticed
+        time.sleep(1) 
+        appldb.wait_for_field_match("SFLOW_SESSION_TABLE", "Ethernet4", {"sample_rate": "256"})
+
 
     def test_Teardown(self, dvs, testlog):
         self.setup_sflow(dvs)