Patch http.client to not do I/O in the event loop (#34194)

homeassistant/block_async_io.py

@@ -0,0 +1,14 @@
+"""Block I/O being done in asyncio."""
+from http.client import HTTPConnection
+
+from homeassistant.util.async_ import protect_loop
+
+
+def enable() -> None:
+    """Enable the detection of I/O in the event loop."""
+    # Prevent urllib3 and requests doing I/O in event loop
+    HTTPConnection.putrequest = protect_loop(HTTPConnection.putrequest)
+
+    # Currently disabled. pytz doing I/O when getting timezone.
+    # Prevent files being opened inside the event loop
+    # builtins.open = protect_loop(builtins.open)

homeassistant/core.py

@@ -36,7 +36,7 @@ from async_timeout import timeout
 import attr
 import voluptuous as vol
 
-from homeassistant import loader, util
+from homeassistant import block_async_io, loader, util
 from homeassistant.const import (
     ATTR_DOMAIN,
     ATTR_FRIENDLY_NAME,
@@ -77,6 +77,9 @@ if TYPE_CHECKING:
     from homeassistant.config_entries import ConfigEntries
     from homeassistant.components.http import HomeAssistantHTTP
 
+
+block_async_io.enable()
+
 # pylint: disable=invalid-name
 T = TypeVar("T")
 CALLABLE_T = TypeVar("CALLABLE_T", bound=Callable)

homeassistant/util/async_.py

@@ -1,9 +1,11 @@
 """Asyncio backports for Python 3.6 compatibility."""
-from asyncio import coroutines, ensure_future
+from asyncio import coroutines, ensure_future, get_running_loop
 from asyncio.events import AbstractEventLoop
 import concurrent.futures
+import functools
 import logging
 import threading
+from traceback import extract_stack
 from typing import Any, Callable, Coroutine
 
 _LOGGER = logging.getLogger(__name__)
@@ -55,3 +57,65 @@ def run_callback_threadsafe(
 
     loop.call_soon_threadsafe(run_callback)
     return future
+
+
+def check_loop() -> None:
+    """Warn if called inside the event loop."""
+    try:
+        get_running_loop()
+        in_loop = True
+    except RuntimeError:
+        in_loop = False
+
+    if not in_loop:
+        return
+
+    found_frame = None
+
+    for frame in reversed(extract_stack()):
+        for path in ("custom_components/", "homeassistant/components/"):
+            try:
+                index = frame.filename.index(path)
+                found_frame = frame
+                break
+            except ValueError:
+                continue
+
+        if found_frame is not None:
+            break
+
+    # Did not source from integration? Hard error.
+    if found_frame is None:
+        raise RuntimeError(
+            "Detected I/O inside the event loop. This is causing stability issues. Please report issue"
+        )
+
+    start = index + len(path)
+    end = found_frame.filename.index("/", start)
+
+    integration = found_frame.filename[start:end]
+
+    if path == "custom_components/":
+        extra = " to the custom component author"
+    else:
+        extra = ""
+
+    _LOGGER.warning(
+        "Detected I/O inside the event loop. This is causing stability issues. Please report issue%s for %s doing I/O at %s, line %s: %s",
+        extra,
+        integration,
+        found_frame.filename[index:],
+        found_frame.lineno,
+        found_frame.line.strip(),
+    )
+
+
+def protect_loop(func: Callable) -> Callable:
+    """Protect function from running in event loop."""
+
+    @functools.wraps(func)
+    def protected_loop_func(*args, **kwargs):  # type: ignore
+        check_loop()
+        return func(*args, **kwargs)
+
+    return protected_loop_func

tests/util/test_async.py

@@ -1,7 +1,7 @@
 """Tests for async util methods from Python source."""
 import asyncio
 from unittest import TestCase
-from unittest.mock import MagicMock, patch
+from unittest.mock import MagicMock, Mock, patch
 
 import pytest
 
@@ -165,3 +165,82 @@ class RunThreadsafeTests(TestCase):
         with self.assertRaises(ValueError) as exc_context:
             self.loop.run_until_complete(future)
         self.assertIn("Invalid!", exc_context.exception.args)
+
+
+async def test_check_loop_async():
+    """Test check_loop detects when called from event loop without integration context."""
+    with pytest.raises(RuntimeError):
+        hasync.check_loop()
+
+
+async def test_check_loop_async_integration(caplog):
+    """Test check_loop detects when called from event loop from integration context."""
+    with patch(
+        "homeassistant.util.async_.extract_stack",
+        return_value=[
+            Mock(
+                filename="/home/paulus/homeassistant/core.py",
+                lineno="23",
+                line="do_something()",
+            ),
+            Mock(
+                filename="/home/paulus/homeassistant/components/hue/light.py",
+                lineno="23",
+                line="self.light.is_on",
+            ),
+            Mock(
+                filename="/home/paulus/aiohue/lights.py",
+                lineno="2",
+                line="something()",
+            ),
+        ],
+    ):
+        hasync.check_loop()
+    assert (
+        "Detected I/O inside the event loop. This is causing stability issues. Please report issue for hue doing I/O at homeassistant/components/hue/light.py, line 23: self.light.is_on"
+        in caplog.text
+    )
+
+
+async def test_check_loop_async_custom(caplog):
+    """Test check_loop detects when called from event loop with custom component context."""
+    with patch(
+        "homeassistant.util.async_.extract_stack",
+        return_value=[
+            Mock(
+                filename="/home/paulus/homeassistant/core.py",
+                lineno="23",
+                line="do_something()",
+            ),
+            Mock(
+                filename="/home/paulus/config/custom_components/hue/light.py",
+                lineno="23",
+                line="self.light.is_on",
+            ),
+            Mock(
+                filename="/home/paulus/aiohue/lights.py",
+                lineno="2",
+                line="something()",
+            ),
+        ],
+    ):
+        hasync.check_loop()
+    assert (
+        "Detected I/O inside the event loop. This is causing stability issues. Please report issue to the custom component author for hue doing I/O at custom_components/hue/light.py, line 23: self.light.is_on"
+        in caplog.text
+    )
+
+
+def test_check_loop_sync(caplog):
+    """Test check_loop does nothing when called from thread."""
+    hasync.check_loop()
+    assert "Detected I/O inside the event loop" not in caplog.text
+
+
+def test_protect_loop_sync():
+    """Test protect_loop calls check_loop."""
+    calls = []
+    with patch("homeassistant.util.async_.check_loop") as mock_loop:
+        hasync.protect_loop(calls.append)(1)
+    assert len(mock_loop.mock_calls) == 1
+    assert calls == [1]