[SNMP Counters]: Update interface list periodically (sonic-net#24)

* Extract init_counters_db from init_sync_d_interface_tables

* Init DB, switch to counters DB when we need this

* Introduce reinit_data method inside of MIBUpdater. This method would be called every 12 updates periods

* Fix trivial error

* Fix issue with omitted db_conn parameter for sync_d synchronization

src/ax_interface/mib.py

@@ -11,6 +11,10 @@
 """
 DEFAULT_UPDATE_FREQUENCY = 5
 
+"""
+Interval between reinit runs (in seconds).
+"""
+DEFAULT_REINIT_RATE = 60
 
 class MIBUpdater:
     """
@@ -20,16 +24,30 @@ class MIBUpdater:
     def __init__(self):
         self.run_event = asyncio.Event()
         self.frequency = DEFAULT_UPDATE_FREQUENCY
+        self.update_counter = 0
+        self.reinit_rate = DEFAULT_REINIT_RATE // DEFAULT_UPDATE_FREQUENCY
 
     async def start(self):
         # Run the update while we are allowed
         while self.run_event.is_set():
+            # reinit internal structures
+            if self.update_counter > self.reinit_rate:
+                self.reinit_data()
+                self.update_counter = 0
+            else:
+                self.update_counter += 1
             # run the background update task
             self.update_data()
             # wait based on our update frequency before executing again.
             # randomize to avoid concurrent update storms.
             await asyncio.sleep(self.frequency + random.randint(-2, 2))
 
+    def reinit_data(self):
+        """
+        Reinit task. Children may override this method.
+        """
+        return
+
     def update_data(self):
         """
         Background task. Children must override this method.

src/sonic_ax_impl/mibs/__init__.py

@@ -78,14 +78,25 @@ def config(**kwargs):
     global redis_kwargs
     redis_kwargs = {k:v for (k,v) in kwargs.items() if k in ['unix_socket_path', 'host', 'port']}
 
-def init_sync_d_interface_tables():
+def init_db():
     """
-    DRY helper method. Connects to and initializes interface maps for SyncD-connected MIB(s).
-    :return: tuple(db_conn, if_name_map, if_id_map, oid_map, if_alias_map)
+    Connects to DB
+    :return: db_conn
     """
     # SyncD database connector. THIS MUST BE INITIALIZED ON A PER-THREAD BASIS.
     # Redis PubSub objects (such as those within swsssdk) are NOT thread-safe.
     db_conn = SonicV2Connector(**redis_kwargs)
+
+    return db_conn
+
+
+def init_sync_d_interface_tables(db_conn):
+    """
+    Initializes interface maps for SyncD-connected MIB(s).
+    :return: tuple(if_name_map, if_id_map, oid_map, if_alias_map)
+    """
+
+    # Make sure we're connected to COUNTERS_DB
     db_conn.connect(COUNTERS_DB)
 
     # { if_name (SONiC) -> sai_id }
@@ -133,7 +144,7 @@ def init_sync_d_interface_tables():
         logger.warning("No alias map found--port names will use SONiC names.")
         if_alias_map = dict(zip(if_name_map.keys(), if_name_map.keys()))
 
-    return db_conn, if_name_map, if_alias_map, if_id_map, oid_sai_map, oid_name_map
+    return if_name_map, if_alias_map, if_id_map, oid_sai_map, oid_name_map
 
 
 def init_sync_d_lag_tables(db_conn):

src/sonic_ax_impl/mibs/ieee802_1ab.py

@@ -30,27 +30,33 @@ class LLDPUpdater(MIBUpdater):
     def __init__(self):
         super().__init__()
 
-        self.db_conn, \
-        self.if_name_map, \
-        self.if_alias_map, \
-        self.if_id_map, \
-        self.oid_sai_map, \
-        self.oid_name_map = mibs.init_sync_d_interface_tables()
-
-        # establish connection to application database.
-        self.db_conn.connect(mibs.APPL_DB)
+        self.db_conn = mibs.init_db()
+        self.reinit_data()
 
         # cache of interface counters
         # { sai_id -> { 'counter': 'value' } }
         self.lldp_counters = {}
-        self.sai_ids = []
         # call our update method once to "seed" data before the "Agent" starts accepting requests.
         self.update_data()
 
+    def reinit_data(self):
+        """
+        Subclass update interface information
+        """
+        self.if_name_map, \
+        self.if_alias_map, \
+        self.if_id_map, \
+        self.oid_sai_map, \
+        self.oid_name_map = mibs.init_sync_d_interface_tables(self.db_conn)
+
     def update_data(self):
         """
-        Subclass update data routine. Updates available sai_ids and LLDP counters.
+        Subclass update data routine. Updates available LLDP counters.
         """
+
+        # establish connection to application database.
+        self.db_conn.connect(mibs.APPL_DB)
+
         self.lldp_counters = {}
         for if_name in self.if_name_map:
             lldp_kvs = self.db_conn.get_all(mibs.APPL_DB, mibs.lldp_entry_table(if_name))

src/sonic_ax_impl/mibs/ietf/rfc1213.py

@@ -93,12 +93,8 @@ class IpMib(metaclass=MIBMeta, prefix='.1.3.6.1.2.1.4'):
 class InterfacesUpdater(MIBUpdater):
     def __init__(self):
         super().__init__()
-        self.db_conn, \
-        self.if_name_map, \
-        self.if_alias_map, \
-        self.if_id_map, \
-        self.oid_sai_map, \
-        self.oid_name_map = mibs.init_sync_d_interface_tables()
+        self.db_conn = mibs.init_db()
+        self.reinit_data()
 
         self.lag_name_if_name_map = {}
         self.if_name_lag_name_map = {}
@@ -110,6 +106,16 @@ def __init__(self):
         # call our update method once to "seed" data before the "Agent" starts accepting requests.
         self.update_data()
 
+    def reinit_data(self):
+        """
+        Subclass update interface information
+        """
+        self.if_name_map, \
+        self.if_alias_map, \
+        self.if_id_map, \
+        self.oid_sai_map, \
+        self.oid_name_map = mibs.init_sync_d_interface_tables(self.db_conn)
+
     def update_data(self):
         """
         Update redis (caches config)

src/sonic_ax_impl/mibs/ietf/rfc2863.py

@@ -48,12 +48,8 @@ class InterfaceMIBUpdater(MIBUpdater):
     def __init__(self):
         super().__init__()
 
-        self.db_conn, \
-        self.if_name_map, \
-        self.if_alias_map, \
-        self.if_id_map, \
-        self.oid_sai_map, \
-        self.oid_name_map = mibs.init_sync_d_interface_tables()
+        self.db_conn = mibs.init_db()
+        self.reinit_data()
 
         self.lag_name_if_name_map = {}
         self.if_name_lag_name_map = {}
@@ -63,6 +59,16 @@ def __init__(self):
         self.if_range = []
         self.update_data()
 
+    def reinit_data(self):
+        """
+        Subclass update interface information
+        """
+        self.if_name_map, \
+        self.if_alias_map, \
+        self.if_id_map, \
+        self.oid_sai_map, \
+        self.oid_name_map = mibs.init_sync_d_interface_tables(self.db_conn)
+
     def update_data(self):
         """
         Update redis (caches config)

src/sonic_ax_impl/mibs/ietf/rfc4292.py

@@ -12,7 +12,7 @@ class RouteUpdater(MIBUpdater):
     def __init__(self):
         super().__init__()
         self.tos = 0 # ipCidrRouteTos
-        self.db_conn, _, _, _, _, _ = mibs.init_sync_d_interface_tables()
+        self.db_conn = mibs.init_db()
         self.update_data()
 
     def update_data(self):

src/sonic_ax_impl/mibs/ietf/rfc4363.py

@@ -12,14 +12,20 @@ def fdb_vlanmac(fdb):
 class FdbUpdater(MIBUpdater):
     def __init__(self):
         super().__init__()
-        self.db_conn, \
+        self.db_conn = mibs.init_db()
+        self.reinit_data()
+        # call our update method once to "seed" data before the "Agent" starts accepting requests.
+        self.update_data()
+
+    def reinit_data(self):
+        """
+        Subclass update interface information
+        """
         self.if_name_map, \
         self.if_alias_map, \
         self.if_id_map, \
         self.oid_sai_map, \
-        self.oid_name_map = mibs.init_sync_d_interface_tables()
-        # call our update method once to "seed" data before the "Agent" starts accepting requests.
-        self.update_data()
+        self.oid_name_map = mibs.init_sync_d_interface_tables(self.db_conn)
 
     def update_data(self):
         """
@@ -50,7 +56,6 @@ def update_data(self):
             self.vlanmac_ifindex_list.append(vlanmac)
         self.vlanmac_ifindex_list.sort()
 
-
     def fdb_ifindex(self, sub_id):
         return self.vlanmac_ifindex_map.get(sub_id, None)