Fix Ctrl+C and tests on Windows. (#1808)

* Fix Ctrl+C on Windows.

* Disable testing of a function N/A on Windows.

* Add test for coverage, avoid crash on missing _stopping.

* Initialise StreamingHTTPResponse.protocol = None

* Improved comments.

* Reduce amount of data in test_request_stream to avoid failures on Windows.

* The Windows test doesn't work on Windows :(

* Use port numbers more likely to be free than 8000.

* Disable the other signal tests on Windows as well.

* Windows doesn't properly support SO_REUSEADDR, so that's disabled in Python, and thus rebinding fails. For successful testing, reuse port instead.

* app.run argument handling: added server kwargs (alike create_server), added warning on extra kwargs, made auto_reload explicit argument. Another go at Windows tests

* Revert "app.run argument handling: added server kwargs (alike create_server), added warning on extra kwargs, made auto_reload explicit argument. Another go at Windows tests"

This reverts commit dc5d682448.

* Use random test server port on most tests. Should avoid port/addr reuse issues.

* Another test to random port instead of 8000.

* Fix deprecation warnings about missing name on Sanic() in tests.

* Linter and typing

* Increase test coverage

* Rewrite test for ctrlc_windows_workaround

* py36 compat

* py36 compat

* py36 compat

* Don't rely on loop internals but add a stopping flag to app.

* App may be restarted.

* py36 compat

* Linter

* Add a constant for OS checking.

Co-authored-by: L. Kärkkäinen <tronic@users.noreply.github.com>

sanic/compat.py

@@ -1,3 +1,6 @@
+import asyncio
+import signal
+
 from sys import argv
 
 from multidict import CIMultiDict  # type: ignore
@@ -23,3 +26,27 @@ else:
 
     async def open_async(file, mode="r", **kwargs):
         return aio_open(file, mode, **kwargs)
+
+
+def ctrlc_workaround_for_windows(app):
+    async def stay_active(app):
+        """Asyncio wakeups to allow receiving SIGINT in Python"""
+        while not die:
+            # If someone else stopped the app, just exit
+            if app.is_stopping:
+                return
+            # Windows Python blocks signal handlers while the event loop is
+            # waiting for I/O. Frequent wakeups keep interrupts flowing.
+            await asyncio.sleep(0.1)
+        # Can't be called from signal handler, so call it from here
+        app.stop()
+
+    def ctrlc_handler(sig, frame):
+        nonlocal die
+        if die:
+            raise KeyboardInterrupt("Non-graceful Ctrl+C")
+        die = True
+
+    die = False
+    signal.signal(signal.SIGINT, ctrlc_handler)
+    app.add_task(stay_active)