Add runner.serve_forever()

CHANGES/2746.feature

@@ -0,0 +1 @@
+Add method `BaseRunner.serve_forever()` that waits forever until being cancelled.

CONTRIBUTORS.txt

@@ -215,6 +215,7 @@ Ludovic Gasc
 Luis Pedrosa
 Lukasz Marcin Dobrzanski
 Makc Belousow
+Maksim Vasilev
 Manuel Miranda
 Marat Sharafutdinov
 Marc Mueller

aiohttp/web_runner.py

@@ -260,13 +260,21 @@
 
 
 class BaseRunner(ABC):
-    __slots__ = ("starting_tasks", "_handle_signals", "_kwargs", "_server", "_sites")
+    __slots__ = (
+        "starting_tasks",
+        "_handle_signals",
+        "_kwargs",
+        "_server",
+        "_sites",
+        "_serve_forever_fut",
+    )
 
     def __init__(self, *, handle_signals: bool = False, **kwargs: Any) -> None:
         self._handle_signals = handle_signals
         self._kwargs = kwargs
         self._server: Optional[Server] = None
         self._sites: List[BaseSite] = []
+        self._serve_forever_fut: Optional[asyncio.Future[None]] = None
 
     @property
     def server(self) -> Optional[Server]:
@@ -306,6 +314,20 @@
         # so we just record all running tasks here and exclude them later.
         self.starting_tasks = asyncio.all_tasks()
 
+    async def serve_forever(self) -> None:
+        if self._serve_forever_fut is not None:
+            raise RuntimeError("Concurrent calls to serve_forever() are not allowed")
+        if self._server is None:
+            raise RuntimeError("Call setup() first")
+
+        loop = asyncio.get_event_loop()
+        self._serve_forever_fut = loop.create_future()
+
+        try:
+            await self._serve_forever_fut
+        finally:
+            self._serve_forever_fut = None
+
     @abstractmethod
     async def shutdown(self) -> None:
         pass  # pragma: no cover

docs/web_advanced.rst

@@ -909,9 +909,7 @@ The simple startup code for serving HTTP site on ``'localhost'``, port
     await runner.setup()
     site = web.TCPSite(runner, 'localhost', 8080)
     await site.start()
-
-    while True:
-        await asyncio.sleep(3600)  # sleep forever
+    await runner.serve_forever()
 
 To stop serving call :meth:`AppRunner.cleanup`::
 

docs/web_reference.rst

@@ -2511,7 +2511,7 @@ application on specific TCP or Unix socket, e.g.::
     site = web.TCPSite(runner, 'localhost', 8080)
     await site.start()
     # wait for finish signal
-    await runner.cleanup()
+    await runner.serve_forever()
 
 
 .. versionadded:: 3.0
@@ -2554,6 +2554,12 @@ application on specific TCP or Unix socket, e.g.::
 
       Stop handling all registered sites and cleanup used resources.
 
+   .. method:: serve_forever()
+      :async:
+
+      Wait forever. Make sure to call :meth:`setup` prior calling this method.
+      Only one :meth:`serve_forever` task is allowed per one runner object.
+
 
 .. class:: AppRunner(app, *, handle_signals=False, **kwargs)
 

tests/test_web_runner.py

@@ -2,7 +2,7 @@
 import asyncio
 import platform
 import signal
-from typing import Any
+from typing import Any, Optional
 from unittest.mock import patch
 
 import pytest
@@ -22,8 +22,8 @@
     asyncio.set_event_loop(loop)
     runners = []
 
-    def go(**kwargs):
-        runner = web.AppRunner(app, **kwargs)
+    def go(app_param: Optional[web.AppRunner] = None, **kwargs):
+        runner = web.AppRunner(app_param or app, **kwargs)
         runners.append(runner)
         return runner
 
@@ -265,3 +265,29 @@
 
     web.run_app(app)
     assert spy.called, "run_app() should work after asyncio.run()."
+
+
+async def test_app_runner_serve_forever_uninitialized(make_runner) -> None:
+    runner = make_runner()
+    with pytest.raises(RuntimeError):
+        await runner.serve_forever()
+
+
+async def test_app_runner_serve_forever_concurrent_call(make_runner, loop) -> None:
+    runner = make_runner()
+    task = loop.create_task(runner.serve_forever())
+    await asyncio.sleep(0.01)
+    with pytest.raises(RuntimeError):
+        await runner.serve_forever()
+    task.cancel()
+
+
+async def test_app_runner_serve_forever_multiple_times(make_runner, loop) -> None:
+    runner = make_runner()
+    for _ in range(3):
+        await runner.setup()
+        task = loop.create_task(runner.serve_forever())
+        await asyncio.sleep(0.01)
+        task.cancel()
+        with pytest.raises(asyncio.CancelledError):
+            await task