Issue #28544: Implement asyncio.Task in C.
This implementation provides additional 10-20% speed boost for
asyncio programs.
The patch also fixes _asynciomodule.c to use Arguments Clinic, and
makes '_schedule_callbacks' an overridable method (as it was in 3.5).
diff --git a/Lib/asyncio/base_futures.py b/Lib/asyncio/base_futures.py
new file mode 100644
index 0000000..64f7845
--- /dev/null
+++ b/Lib/asyncio/base_futures.py
@@ -0,0 +1,70 @@
+__all__ = []
+
+import concurrent.futures._base
+import reprlib
+
+from . import events
+
+Error = concurrent.futures._base.Error
+CancelledError = concurrent.futures.CancelledError
+TimeoutError = concurrent.futures.TimeoutError
+
+
+class InvalidStateError(Error):
+ """The operation is not allowed in this state."""
+
+
+# States for Future.
+_PENDING = 'PENDING'
+_CANCELLED = 'CANCELLED'
+_FINISHED = 'FINISHED'
+
+
+def isfuture(obj):
+ """Check for a Future.
+
+ This returns True when obj is a Future instance or is advertising
+ itself as duck-type compatible by setting _asyncio_future_blocking.
+ See comment in Future for more details.
+ """
+ return getattr(obj, '_asyncio_future_blocking', None) is not None
+
+
+def _format_callbacks(cb):
+ """helper function for Future.__repr__"""
+ size = len(cb)
+ if not size:
+ cb = ''
+
+ def format_cb(callback):
+ return events._format_callback_source(callback, ())
+
+ if size == 1:
+ cb = format_cb(cb[0])
+ elif size == 2:
+ cb = '{}, {}'.format(format_cb(cb[0]), format_cb(cb[1]))
+ elif size > 2:
+ cb = '{}, <{} more>, {}'.format(format_cb(cb[0]),
+ size - 2,
+ format_cb(cb[-1]))
+ return 'cb=[%s]' % cb
+
+
+def _future_repr_info(future):
+ # (Future) -> str
+ """helper function for Future.__repr__"""
+ info = [future._state.lower()]
+ if future._state == _FINISHED:
+ if future._exception is not None:
+ info.append('exception={!r}'.format(future._exception))
+ else:
+ # use reprlib to limit the length of the output, especially
+ # for very long strings
+ result = reprlib.repr(future._result)
+ info.append('result={}'.format(result))
+ if future._callbacks:
+ info.append(_format_callbacks(future._callbacks))
+ if future._source_traceback:
+ frame = future._source_traceback[-1]
+ info.append('created at %s:%s' % (frame[0], frame[1]))
+ return info