Implement get on CaseInsensitiveDict

get was previously provided by the parent class which
had to raise KeyError for missing values. Since try/except
is only cheap for the non-exception case the performance
was not good when the key was missing

similar to python/cpython#106665
but in the HA case we call this even more frequently

async_upnp_client/ssdp_listener.py

@@ -41,9 +41,9 @@
 def valid_search_headers(headers: CaseInsensitiveDict) -> bool:
     """Validate if this search is usable."""
     # pylint: disable=invalid-name
-    udn = headers.get("_udn")  # type: Optional[str]
-    st = headers.get("st")  # type: Optional[str]
-    location = headers.get("location", "")  # type: str
+    udn = headers.get_lower("_udn")  # type: Optional[str]
+    st = headers.get_lower("st")  # type: Optional[str]
+    location = headers.get_lower("location", "")  # type: str
     return bool(
         udn
         and st
@@ -60,10 +60,10 @@ def valid_search_headers(headers: CaseInsensitiveDict) -> bool:
 def valid_advertisement_headers(headers: CaseInsensitiveDict) -> bool:
     """Validate if this advertisement is usable for connecting to a device."""
     # pylint: disable=invalid-name
-    udn = headers.get("_udn")  # type: Optional[str]
-    nt = headers.get("nt")  # type: Optional[str]
-    nts = headers.get("nts")  # type: Optional[str]
-    location = headers.get("location", "")  # type: str
+    udn = headers.get_lower("_udn")  # type: Optional[str]
+    nt = headers.get_lower("nt")  # type: Optional[str]
+    nts = headers.get_lower("nts")  # type: Optional[str]
+    location = headers.get_lower("location", "")  # type: str
     return bool(
         udn
         and nt
@@ -81,15 +81,15 @@ def valid_advertisement_headers(headers: CaseInsensitiveDict) -> bool:
 def valid_byebye_headers(headers: CaseInsensitiveDict) -> bool:
     """Validate if this advertisement has required headers for byebye."""
     # pylint: disable=invalid-name
-    udn = headers.get("_udn")  # type: Optional[str]
-    nt = headers.get("nt")  # type: Optional[str]
-    nts = headers.get("nts")  # type: Optional[str]
+    udn = headers.get_lower("_udn")  # type: Optional[str]
+    nt = headers.get_lower("nt")  # type: Optional[str]
+    nts = headers.get_lower("nts")  # type: Optional[str]
     return bool(udn and nt and nts)
 
 
 def extract_valid_to(headers: CaseInsensitiveDict) -> datetime:
     """Extract/create valid to."""
-    cache_control = headers.get("cache-control", "")
+    cache_control = headers.get_lower("cache-control", "")
     match = CACHE_CONTROL_RE.search(cache_control)
     if match:
         max_age = int(match[1])
@@ -247,7 +247,7 @@ def ip_version_from_location(location: str) -> Optional[int]:
 
 def location_changed(ssdp_device: SsdpDevice, headers: CaseInsensitiveDict) -> bool:
     """Test if location changed for device."""
-    new_location = headers.get("location", "")
+    new_location = headers.get_lower("location", "")
     if not new_location:
         return False
 

async_upnp_client/utils.py

@@ -41,12 +41,12 @@ def as_lower_dict(self) -> Dict[str, Any]:
         """Return the underlying dict in lowercase."""
         return {k.lower(): v for k, v in self._data.items()}
 
-    def get_lower(self, lower_key: str) -> Any:
+    def get_lower(self, lower_key: str, default: Any = None) -> Any:
         """Get a lower case key."""
         data_key = self._case_map.get(lower_key, _SENTINEL)
         if data_key is not _SENTINEL:
-            return self._data[data_key]
-        return None
+            return self._data.get(data_key, default)
+        return default
 
     def replace(self, new_data: abcMapping) -> None:
         """Replace the underlying dict."""
@@ -56,6 +56,19 @@ def replace(self, new_data: abcMapping) -> None:
             self._data = {**new_data}
         self._case_map = {k.lower(): k for k in self._data}
 
+    def get(self, key: str, default: Any = None) -> Any:
+        """Get item with default.
+
+        This implementation is case insensitive and avoids
+        calling __getitem__ which would raise KeyError and
+        cause unnecessary exception handling.
+        """
+        case_map = self._case_map
+        data_key = case_map.get(key, case_map.get(key.lower(), _SENTINEL))
+        if data_key is not _SENTINEL:
+            return self._data.get(data_key, default)
+        return default
+
     def __setitem__(self, key: str, value: Any) -> None:
         """Set item."""
         lower_key = key.lower()