Attempt to fix CPU utilisation bug by preventing the heartbeat callback leak in the SSE stream handlers and replacing Timer-based with Event-based threads. Also compiled regexes in advance for DXCC callsign lookups for efficiency, and fixed my misunderstanding of what Queue.empty() does

core/lookup_helper.py

@@ -101,6 +101,10 @@ class LookupHelper:
         else:
             logging.error("Could not download DXCC data, flags and similar data may be missing!")
 
+        # Precompile regex matches for DXCCs to improve efficiency when iterating through them
+        for dxcc in self.DXCC_DATA.values():
+            dxcc["_prefixRegexCompiled"] = re.compile(dxcc["prefixRegex"])
+
     # Download the cty.plist file from country-files.com on first startup. The pyhamtools lib can actually download and use
     # this itself, but it's occasionally offline which causes it to throw an error. By downloading it separately, we can
     # catch errors and handle them, falling back to a previous copy of the file in the cache, and we can use the
@@ -559,7 +563,7 @@ class LookupHelper:
     # Utility method to get generic DXCC data from our lookup table, if we can find it
     def get_dxcc_data_for_callsign(self, call):
         for entry in self.DXCC_DATA.values():
-            if re.match(entry["prefixRegex"], call):
+            if entry["_prefixRegexCompiled"].match(call):
                 return entry
         return None