Experiment: Wrap all capnp code in a context-manager to avoid segfaults (#317)

* Experiment: Wrap all capnp code in a context-manager

* Fix segfault in on_disconnect

examples/async_calculator_client.py

@@ -306,4 +306,4 @@ async def cmd_main(host):
 
 
 if __name__ == "__main__":
-    asyncio.run(cmd_main(parse_args().host))
+    asyncio.run(capnp.run(cmd_main(parse_args().host)))

examples/async_calculator_server.py

@@ -131,4 +131,4 @@ async def main():
 
 
 if __name__ == "__main__":
-    asyncio.run(main())
+    asyncio.run(capnp.run(main()))

examples/async_client.py

@@ -24,11 +24,6 @@ class StatusSubscriber(thread_capnp.Example.StatusSubscriber.Server):
         print("status: {}".format(time.time()))
 
 
-async def background(cap):
-    subscriber = StatusSubscriber()
-    await cap.subscribeStatus(subscriber)
-
-
 async def main(host):
     host, port = host.split(":")
     connection = await capnp.AsyncIoStream.create_connection(host=host, port=port)
@@ -36,7 +31,7 @@ async def main(host):
     cap = client.bootstrap().cast_as(thread_capnp.Example)
 
     # Start background task for subscriber
-    asyncio.create_task(background(cap))
+    task = asyncio.ensure_future(cap.subscribeStatus(StatusSubscriber()))
 
     # Run blocking tasks
     print("main: {}".format(time.time()))
@@ -47,12 +42,14 @@ async def main(host):
     await cap.longRunning()
     print("main: {}".format(time.time()))
 
+    task.cancel()
+
 
 if __name__ == "__main__":
     args = parse_args()
-    asyncio.run(main(args.host))
+    asyncio.run(capnp.run(main(args.host)))
 
     # Test that we can run multiple asyncio loops in sequence. This is particularly tricky, because
     # main contains a background task that we never cancel. The entire loop gets cleaned up anyways,
     # and we can start a new loop.
-    asyncio.run(main(args.host))
+    asyncio.run(capnp.run(main(args.host)))

examples/async_reconnecting_ssl_client.py

@@ -41,11 +41,6 @@ async def watch_connection(cap):
             return False
 
 
-async def background(cap):
-    subscriber = StatusSubscriber()
-    await cap.subscribeStatus(subscriber)
-
-
 async def main(host):
     addr, port = host.split(":")
 
@@ -71,7 +66,9 @@ async def main(host):
 
     # Start watcher to restart socket connection if it is lost and subscriber background task
     background_tasks = asyncio.gather(
-        background(cap), watch_connection(cap), return_exceptions=True
+        cap.subscribeStatus(StatusSubscriber()),
+        watch_connection(cap),
+        return_exceptions=True,
     )
 
     # Run blocking tasks
@@ -96,7 +93,7 @@ if __name__ == "__main__":
     while retry:
         loop = asyncio.new_event_loop()
         try:
-            retry = not loop.run_until_complete(main(parse_args().host))
+            retry = not loop.run_until_complete(capnp.run(main(parse_args().host)))
         except RuntimeError:
             # If an IO is hung, the event loop will be stopped
             # and will throw RuntimeError exception

examples/async_server.py

@@ -46,4 +46,4 @@ async def main():
 
 
 if __name__ == "__main__":
-    asyncio.run(main())
+    asyncio.run(capnp.run(main()))

examples/async_socket_message_client.py

@@ -50,4 +50,4 @@ async def main(host):
 
 if __name__ == "__main__":
     args = parse_args()
-    asyncio.run(main(args.host))
+    asyncio.run(capnp.run(main(args.host)))

examples/async_socket_message_server.py

@@ -59,4 +59,4 @@ async def main():
 
 
 if __name__ == "__main__":
-    asyncio.run(main())
+    asyncio.run(capnp.run(main()))

examples/async_ssl_calculator_client.py

@@ -330,4 +330,4 @@ if __name__ == "__main__":
     # https://bugs.python.org/issue36709
     # asyncio.run(main(parse_args().host), loop=loop, debug=True)
     loop = asyncio.get_event_loop()
-    loop.run_until_complete(main(parse_args().host))
+    loop.run_until_complete(capnp.run(main(parse_args().host)))

examples/async_ssl_calculator_server.py

@@ -155,4 +155,4 @@ async def main():
 
 
 if __name__ == "__main__":
-    asyncio.run(main())
+    asyncio.run(capnp.run(main()))

examples/async_ssl_client.py

@@ -15,8 +15,7 @@ this_dir = os.path.dirname(os.path.abspath(__file__))
 
 def parse_args():
     parser = argparse.ArgumentParser(
-        usage="Connects to the Example thread server \
-at the given address and does some RPCs"
+        usage="Connects to the Example thread server at the given address and does some RPCs"
     )
     parser.add_argument("host", help="HOST:PORT")
 
@@ -26,15 +25,10 @@ at the given address and does some RPCs"
 class StatusSubscriber(thread_capnp.Example.StatusSubscriber.Server):
     """An implementation of the StatusSubscriber interface"""
 
-    def status(self, value, **kwargs):
+    async def status(self, value, **kwargs):
         print("status: {}".format(time.time()))
 
 
-async def background(cap):
-    subscriber = StatusSubscriber()
-    await cap.subscribeStatus(subscriber)
-
-
 async def main(host):
     addr, port = host.split(":")
 
@@ -59,7 +53,7 @@ async def main(host):
     cap = client.bootstrap().cast_as(thread_capnp.Example)
 
     # Start background task for subscriber
-    asyncio.create_task(background(cap))
+    task = asyncio.ensure_future(cap.subscribeStatus(StatusSubscriber()))
 
     # Run blocking tasks
     print("main: {}".format(time.time()))
@@ -70,10 +64,12 @@ async def main(host):
     await cap.longRunning()
     print("main: {}".format(time.time()))
 
+    task.cancel()
+
 
 if __name__ == "__main__":
     # Using asyncio.run hits an asyncio ssl bug
     # https://bugs.python.org/issue36709
     # asyncio.run(main(parse_args().host), loop=loop, debug=True)
     loop = asyncio.get_event_loop()
-    loop.run_until_complete(main(parse_args().host))
+    loop.run_until_complete(capnp.run(main(parse_args().host)))

examples/async_ssl_server.py

@@ -71,4 +71,4 @@ async def main():
 
 
 if __name__ == "__main__":
-    asyncio.run(main())
+    asyncio.run(capnp.run(main()))