Reduce latency in storage by making the tasks eager (#111500)

* Reduce latancy to load storage by making the task eager

This changes the semantics a bit under the hood because it
can raise sooner which means we do not store the task
as _load_task if it raises right away. That means
concurrent calls that result in failure are likely to try
again now which will be a tiny performance hit for this
case.

* fix

* will now finish in time

homeassistant/helpers/storage.py

@@ -133,12 +133,16 @@ class Store(Generic[_T]):
         Will ensure that when a call comes in while another one is in progress,
         the second call will wait and return the result of the first call.
         """
-        if self._load_task is None:
-            self._load_task = self.hass.async_create_task(
-                self._async_load(), f"Storage load {self.key}"
-            )
+        if self._load_task:
+            return await self._load_task
 
-        return await self._load_task
+        load_task = self.hass.async_create_task(
+            self._async_load(), f"Storage load {self.key}", eager_start=True
+        )
+        if not load_task.done():
+            # Only set the load task if it didn't complete immediately
+            self._load_task = load_task
+        return await load_task
 
     async def _async_load(self) -> _T | None:
         """Load the data and ensure the task is removed."""
@@ -318,7 +322,9 @@ class Store(Generic[_T]):
             # wrote. Reschedule the timer to the next write time.
             self._async_reschedule_delayed_write(self._next_write_time)
             return
-        self.hass.async_create_task(self._async_callback_delayed_write())
+        self.hass.async_create_task(
+            self._async_callback_delayed_write(), eager_start=True
+        )
 
     @callback
     def _async_ensure_final_write_listener(self) -> None:

tests/helpers/test_storage.py

@@ -115,7 +115,7 @@ async def test_loading_parallel(
     results = await asyncio.gather(store.async_load(), store.async_load())
 
     assert results[0] == MOCK_DATA
-    assert results[0] is results[1]
+    assert results[1] == MOCK_DATA
     assert caplog.text.count(f"Loading data for {store.key}")
 
 
@@ -795,6 +795,25 @@ async def test_os_error_is_fatal(tmpdir: py.path.local) -> None:
         ):
             await store.async_load()
 
+        # Verify second load is also failing
+        with pytest.raises(OSError), patch(
+            "homeassistant.helpers.storage.json_util.load_json", side_effect=OSError
+        ):
+            await store.async_load()
+
+        await hass.async_stop(force=True)
+
+
+async def test_json_load_failure(tmpdir: py.path.local) -> None:
+    """Test json load raising HomeAssistantError."""
+    async with async_test_home_assistant() as hass:
+        tmp_storage = await hass.async_add_executor_job(tmpdir.mkdir, "temp_storage")
+        hass.config.config_dir = tmp_storage
+
+        store = storage.Store(
+            hass, MOCK_VERSION_2, MOCK_KEY, minor_version=MOCK_MINOR_VERSION_1
+        )
+        await store.async_save({"hello": "world"})
         base_os_error = OSError()
         base_os_error.errno = 30
         home_assistant_error = HomeAssistantError()