In debug mode, detect calls to call_soon() from greenthreads which are not

threadsafe (would not wake up the event loop).

3 files changed, 51 insertions, 1 deletions

diff --git a/README b/README
index cbb2ca0..d316cee 100644
--- a/README
+++ b/README
@@ -4,6 +4,22 @@ asyncio event loop scheduling callbacks in eventlet.
 * aiogreen at PyPI: https://pypi.python.org/pypi/aiogreen
 
 
+Usage
+=====
+
+aiogreen implements the asyncio API, see asyncio documentation:
+https://docs.python.org/dev/library/asyncio.html
+
+To support Python 2, you can use Trollius which uses ``yield`` instead
+of ``yield from`` for coroutines:
+http://trollius.readthedocs.org/
+
+Using the event loop from greenthreads is not safe: calls to the event loop
+must be passed to ``call_soon_threadsafe()``. Example to stop the event loop:
+
+    eventlet.spawn(loop.call_soon_threadsafe, loop.stop)
+
+
 Installation
 ============
 
@@ -87,6 +103,8 @@ Changes:
   in eventlet.
 * add_reader() and add_writer() now cancels the previous handle and sets
   a new handle
+* In debug mode, detect calls to call_soon() from greenthreads which are not
+  threadsafe (would not wake up the event loop).
 
 2014-11-19: version 0.1
 -----------------------
diff --git a/aiogreen.py b/aiogreen.py
index a57a47a..3a46956 100644
--- a/aiogreen.py
+++ b/aiogreen.py
@@ -199,6 +199,14 @@ class EventLoop(asyncio.SelectorEventLoop):
     def time(self):
         return self._hub.clock()
 
+    def _assert_is_current_event_loop(self):
+        super(EventLoop, self)._assert_is_current_event_loop()
+        if self._selector._event:
+            # call_soon() must not be called while selector.select() is
+            # running, it does not wake up the event loop
+            raise RuntimeError(
+                "Non-thread-safe operation invoked from a greenthread")
+
 
 class EventLoopPolicy(asyncio.DefaultEventLoopPolicy):
     _loop_factory = EventLoop
diff --git a/tests/test_eventlet.py b/tests/test_eventlet.py
index d50c8ee..9e6b699 100644
--- a/tests/test_eventlet.py
+++ b/tests/test_eventlet.py
@@ -2,6 +2,30 @@ import eventlet
 import tests
 
 class EventletTests(tests.TestCase):
+    def test_stop(self):
+        def func():
+            eventlet.spawn(self.loop.call_soon_threadsafe, self.loop.stop)
+
+        def schedule_greenthread():
+            eventlet.spawn(func)
+
+        self.loop.call_soon(schedule_greenthread)
+        self.loop.run_forever()
+
+    def test_soon(self):
+        result = []
+
+        def func():
+            result.append("spawn")
+            self.loop.call_soon_threadsafe(self.loop.stop)
+
+        def schedule_greenthread():
+            eventlet.spawn(func)
+
+        self.loop.call_soon(schedule_greenthread)
+        self.loop.run_forever()
+        self.assertEqual(result, ["spawn"])
+
     def test_soon_spawn(self):
         result = []
 
@@ -14,7 +38,7 @@ class EventletTests(tests.TestCase):
 
         def schedule_greenthread():
             eventlet.spawn(func1)
-            eventlet.spawn_after(0.001, func2)
+            eventlet.spawn_after(0.010, func2)
 
         self.loop.call_soon(schedule_greenthread)
         self.loop.run_forever()