asyncio: sync with Tulip

- Tulip issue 185: Add a create_task() method to event loops. The create_task()
  method can be overriden in custom event loop to implement their own task
  class. For example, greenio and Pulsar projects use their own task class. The
  create_task() method is now preferred over creating directly task using the
  Task class.
- tests: fix a warning
- fix typo in the name of a test function
- Update AbstractEventLoop: add new event loop methods; update also the unit test

5 files changed, 20 insertions, 3 deletions

diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index 2230dc2..52c5517 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -151,6 +151,12 @@ class BaseEventLoop(events.AbstractEventLoop):
                 % (self.__class__.__name__, self.is_running(),
                    self.is_closed(), self.get_debug()))
 
+    def create_task(self, coro):
+        """Schedule a coroutine object.
+
+        Return a task object."""
+        return tasks.Task(coro, loop=self)
+
     def _make_socket_transport(self, sock, protocol, waiter=None, *,
                                extra=None, server=None):
         """Create socket transport."""
diff --git a/Lib/asyncio/events.py b/Lib/asyncio/events.py
index b389cfb..1f5e582 100644
--- a/Lib/asyncio/events.py
+++ b/Lib/asyncio/events.py
@@ -200,6 +200,10 @@ class AbstractEventLoop:
         """Return whether the event loop is currently running."""
         raise NotImplementedError
 
+    def is_closed(self):
+        """Returns True if the event loop was closed."""
+        raise NotImplementedError
+
     def close(self):
         """Close the loop.
 
@@ -225,6 +229,11 @@ class AbstractEventLoop:
     def time(self):
         raise NotImplementedError
 
+    # Method scheduling a coroutine object: create a task.
+
+    def create_task(self, coro):
+        raise NotImplementedError
+
     # Methods for interacting with threads.
 
     def call_soon_threadsafe(self, callback, *args):
diff --git a/Lib/asyncio/streams.py b/Lib/asyncio/streams.py
index a10b969..9bde218 100644
--- a/Lib/asyncio/streams.py
+++ b/Lib/asyncio/streams.py
@@ -213,7 +213,7 @@ class StreamReaderProtocol(FlowControlMixin, protocols.Protocol):
             res = self._client_connected_cb(self._stream_reader,
                                             self._stream_writer)
             if coroutines.iscoroutine(res):
-                tasks.Task(res, loop=self._loop)
+                self._loop.create_task(res)
 
     def connection_lost(self, exc):
         if exc is None:
diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
index 8c7217b..befc296 100644
--- a/Lib/asyncio/tasks.py
+++ b/Lib/asyncio/tasks.py
@@ -505,7 +505,9 @@ def async(coro_or_future, *, loop=None):
             raise ValueError('loop argument must agree with Future')
         return coro_or_future
     elif coroutines.iscoroutine(coro_or_future):
-        task = Task(coro_or_future, loop=loop)
+        if loop is None:
+            loop = events.get_event_loop()
+        task = loop.create_task(coro_or_future)
         if task._source_traceback:
             del task._source_traceback[-1]
         return task
diff --git a/Lib/asyncio/test_utils.py b/Lib/asyncio/test_utils.py
index ef3be23..6abcaf1 100644
--- a/Lib/asyncio/test_utils.py
+++ b/Lib/asyncio/test_utils.py
@@ -48,7 +48,7 @@ def run_briefly(loop):
     def once():
         pass
     gen = once()
-    t = tasks.Task(gen, loop=loop)
+    t = loop.create_task(gen)
     # Don't log a warning if the task is not done after run_until_complete().
     # It occurs if the loop is stopped or if a task raises a BaseException.
     t._log_destroy_pending = False