fix: improve performance of ServiceInfo.async_request (#1205)

src/zeroconf/_services/info.py

@@ -39,11 +39,7 @@
 from .._logger import log
 from .._protocol.outgoing import DNSOutgoing
 from .._updates import RecordUpdate, RecordUpdateListener
-from .._utils.asyncio import (
-    get_running_loop,
-    run_coro_with_timeout,
-    wait_event_or_timeout,
-)
+from .._utils.asyncio import get_running_loop, run_coro_with_timeout
 from .._utils.name import service_type_name
 from .._utils.net import IPVersion, _encode_address
 from .._utils.time import current_time_millis, millis_to_seconds
@@ -131,6 +127,7 @@ class ServiceInfo(RecordUpdateListener):
         "host_ttl",
         "other_ttl",
         "interface_index",
+        "_new_records_futures",
     )
 
     def __init__(
@@ -177,7 +174,7 @@ def __init__(
         self.host_ttl = host_ttl
         self.other_ttl = other_ttl
         self.interface_index = interface_index
-        self._notify_event: Optional[asyncio.Event] = None
+        self._new_records_futures: List[asyncio.Future] = []
 
     @property
     def name(self) -> str:
@@ -235,9 +232,14 @@ def properties(self) -> Dict:
 
     async def async_wait(self, timeout: float) -> None:
         """Calling task waits for a given number of milliseconds or until notified."""
-        if self._notify_event is None:
-            self._notify_event = asyncio.Event()
-        await wait_event_or_timeout(self._notify_event, timeout=millis_to_seconds(timeout))
+        loop = asyncio.get_running_loop()
+        future = loop.create_future()
+        self._new_records_futures.append(future)
+        handle = loop.call_later(millis_to_seconds(timeout), future.set_result, None)
+        try:
+            await future
+        finally:
+            handle.cancel()
 
     def addresses_by_version(self, version: IPVersion) -> List[bytes]:
         """List addresses matching IP version.
@@ -409,9 +411,11 @@ def async_update_records(self, zc: 'Zeroconf', now: float, records: List[RecordU
 
         This method will be run in the event loop.
         """
-        if self._process_records_threadsafe(zc, now, records) and self._notify_event:
-            self._notify_event.set()
-            self._notify_event.clear()
+        if self._process_records_threadsafe(zc, now, records) and self._new_records_futures:
+            for future in self._new_records_futures:
+                if not future.done():
+                    future.set_result(None)
+            self._new_records_futures.clear()
 
     def _process_records_threadsafe(self, zc: 'Zeroconf', now: float, records: List[RecordUpdate]) -> bool:
         """Thread safe record updating.
@@ -591,12 +595,13 @@ def set_server_if_missing(self) -> None:
             self.server = self.name
             self.server_key = self.server.lower()
 
-    def load_from_cache(self, zc: 'Zeroconf') -> bool:
+    def load_from_cache(self, zc: 'Zeroconf', now: Optional[float] = None) -> bool:
         """Populate the service info from the cache.
 
         This method is designed to be threadsafe.
         """
-        now = current_time_millis()
+        if not now:
+            now = current_time_millis()
         original_server_key = self.server_key
         cached_srv_record = zc.cache.get_by_details(self.name, _TYPE_SRV, _CLASS_IN)
         if cached_srv_record:
@@ -664,11 +669,13 @@ async def async_request(
         """
         if not zc.started:
             await zc.async_wait_for_start()
-        if self.load_from_cache(zc):
+
+        now = current_time_millis()
+
+        if self.load_from_cache(zc, now):
             return True
 
         first_request = True
-        now = current_time_millis()
         delay = _LISTENER_TIME
         next_ = now
         last = now + timeout
@@ -683,7 +690,7 @@ async def async_request(
                     )
                     first_request = False
                     if not out.questions:
-                        return self.load_from_cache(zc)
+                        return self.load_from_cache(zc, now)
                     zc.async_send(out, addr, port)
                     next_ = now + delay
                     delay *= 2