[counter] Clear counter table when init (sonic-net#45)

Author: yaqiangz

src/relay.cpp

@@ -322,7 +322,6 @@ void initialize_counter(std::shared_ptr<swss::DBConnector> state_db, std::string
     std::string table_name = counter_table + ifname;
 
     auto init_value = gen_counter_json_str(DHCPv6_MESSAGE_TYPE_UNKNOWN, 0);
-    state_db->del(table_name);
     state_db->hset(table_name, "RX", init_value);
     state_db->hset(table_name, "TX", init_value);
 }
@@ -1484,6 +1483,23 @@ void prepare_socket_callback(event_base *base, int socket, void (*cb)(evutil_soc
     event_add(event, NULL);
 }
 
+/**
+ * @code clear_counter(std::shared_ptr<swss::DBConnector> state_db);
+ * 
+ * @brief Clear all counter
+ * 
+ * @param state_db      state_db connector pointer
+ * 
+ */
+void clear_counter(std::shared_ptr<swss::DBConnector> state_db) {
+    std::string match_pattern = counter_table + std::string("*");
+    auto keys = state_db->keys(match_pattern);
+
+    for (auto &itr : keys) {
+        state_db->del(itr);
+    }
+}
+
 /**
  * @code                loop_relay(std::unordered_map<relay_config> &vlans);
  * 
@@ -1513,6 +1529,8 @@ void loop_relay(std::unordered_map<std::string, relay_config> &vlans) {
     prepare_socket_callback(base, out_filter, outbound_callback, reinterpret_cast<void *>(state_db.get()));
     sockets.push_back(out_filter);
 
+    clear_counter(state_db);
+
     int lo_sock = -1;
     if (dual_tor_sock) {
         std::string lo_string(loopback);

src/relay.h

@@ -559,3 +559,13 @@ void packet_counting_handler(uint8_t *buffer, ssize_t length, std::string &ifnam
  * 
  */
 void prepare_socket_callback(event_base *base, int socket, void (*cb)(evutil_socket_t, short, void *), void *arg);
+
+/**
+ * @code clear_counter(std::shared_ptr<swss::DBConnector> state_db);
+ * 
+ * @brief Clear all counter
+ * 
+ * @param state_db      state_db connector pointer
+ * 
+ */
+void clear_counter(std::shared_ptr<swss::DBConnector> state_db);

test/mock_relay.cpp

@@ -325,6 +325,17 @@ TEST(counter, initialize_counter)
   EXPECT_TRUE(state_db->hexists("DHCPv6_COUNTER_TABLE|Vlan1000", "TX"));
 }
 
+TEST(counter, clear_counter)
+{
+  std::shared_ptr<swss::DBConnector> state_db = std::make_shared<swss::DBConnector> ("STATE_DB", 0);
+  std::string ifname = "Vlan1000";
+  initialize_counter(state_db, ifname);
+  EXPECT_TRUE(state_db->hexists("DHCPv6_COUNTER_TABLE|Vlan1000", "RX"));
+  EXPECT_TRUE(state_db->hexists("DHCPv6_COUNTER_TABLE|Vlan1000", "TX"));
+  clear_counter(state_db);
+  EXPECT_FALSE(state_db->exists("DHCPv6_COUNTER_TABLE|Vlan1000"));
+}
+
 TEST(counter, increase_counter)
 {
   std::shared_ptr<swss::DBConnector> state_db = std::make_shared<swss::DBConnector> ("STATE_DB", 0);