Fix typing, apply simplifications and flatten code

python/nav/dhcp/generic_metrics.py

@@ -15,12 +15,7 @@
 #
 
 
-
-
-#TODO: rename from DhcpMetricSource to DhcpCollector
-
-
-
+# TODO: rename from DhcpMetricSource to DhcpCollector
 
 
 """
@@ -48,23 +43,23 @@
 from nav.metrics.templates import metric_path_for_subnet_dhcp
 
 
-
 class DhcpMetricKey(Enum):
     """
     Specifies what kind of value a DHCP metric represents.
 
     TOTAL:     value is the maximum possible amount of active leases in the
                subnet
-    
+
     ASSIGNED:  value is the current amount of active leases in the subnet
-    
+
     DECLINED:  value is the amount of DHCP-maintained addresses in use by an
                entity unknown to the server and thus not available for
                assignment. (Should ideally always be zero)
 
     For more detailed info on DECLINED, see e.g.
     https://kea.readthedocs.io/en/kea-2.2.0/arm/dhcp6-srv.html#duplicate-addresses-dhcpdecline-support
     """
+
     TOTAL = "total"
     ASSIGNED = "assigned"
     DECLINED = "declined"
@@ -75,7 +70,7 @@ def __str__(self):
 
 @dataclass(frozen=True)
 class DhcpMetric:
-    timestamp: datetime
+    timestamp: float
     subnet_prefix: IP
     key: DhcpMetricKey
     value: int
@@ -88,16 +83,14 @@ class DhcpMetricSource:
     graphite server. Subclasses need to implement `fetch_metrics`.
     """
 
-    def fetch_metrics(self) -> Iterator[DhcpMetric]:
+    def fetch_metrics(self) -> list[DhcpMetric]:
         """
         Fetch DhcpMetrics having keys `TOTAL` and `ASSIGNED` for each subnet of the
         DHCP server at current point of time.
         """
         raise NotImplementedError
 
-    def fetch_metrics_to_graphite(
-        self, host=None, port=None
-    ):
+    def fetch_metrics_to_graphite(self, host=None, port=None):
         """
         Fetch metrics describing total amount of addresses
         (DhcpMetricKey.TOTAL) and amount of addresses that have been