Speed up live history setup if there is no pending data to commit (#86942)

homeassistant/components/recorder/core.py

@@ -1044,6 +1044,8 @@ class Recorder(threading.Thread):
 
     async def async_block_till_done(self) -> None:
         """Async version of block_till_done."""
+        if self._queue.empty() and not self._event_session_has_pending_writes():
+            return
         event = asyncio.Event()
         self.queue_task(SynchronizeTask(event))
         await event.wait()

tests/components/logbook/test_websocket_api.py

@@ -2303,6 +2303,11 @@ async def test_recorder_is_far_behind(recorder_mock, hass, hass_ws_client, caplo
     hass.bus.async_fire("mock_event", {"device_id": device.id, "message": "1"})
     await hass.async_block_till_done()
 
+    msg = await asyncio.wait_for(websocket_client.receive_json(), 2)
+    assert msg["id"] == 7
+    assert msg["type"] == "event"
+    assert msg["event"]["events"] == []
+
     msg = await asyncio.wait_for(websocket_client.receive_json(), 2)
     assert msg["id"] == 7
     assert msg["type"] == "event"