Issue #24487: Rename async() -> ensure_future() in asyncio docs.

Patch by Martin Panter.

Doc/library/asyncio-dev.rst

@@ -99,7 +99,7 @@ To schedule a callback from a different thread, the
 :meth:`BaseEventLoop.call_soon_threadsafe` method should be used. Example to
 schedule a coroutine from a different thread::
 
-    loop.call_soon_threadsafe(asyncio.async, coro_func())
+    loop.call_soon_threadsafe(asyncio.ensure_future, coro_func())
 
 Most asyncio objects are not thread safe. You should only worry if you access
 objects outside the event loop. For example, to cancel a future, don't call
@@ -162,10 +162,10 @@ Detect coroutine objects never scheduled
 ----------------------------------------
 
 When a coroutine function is called and its result is not passed to
-:func:`async` or to the :meth:`BaseEventLoop.create_task` method, the execution
-of the coroutine object will never be scheduled which is probably a bug.
-:ref:`Enable the debug mode of asyncio <asyncio-debug-mode>` to :ref:`log a
-warning <asyncio-logger>` to detect it.
+:func:`ensure_future` or to the :meth:`BaseEventLoop.create_task` method,
+the execution of the coroutine object will never be scheduled which is
+probably a bug.  :ref:`Enable the debug mode of asyncio <asyncio-debug-mode>`
+to :ref:`log a warning <asyncio-logger>` to detect it.
 
 Example with the bug::
 
@@ -184,7 +184,7 @@ Output in debug mode::
       File "test.py", line 7, in <module>
         test()
 
-The fix is to call the :func:`async` function or the
+The fix is to call the :func:`ensure_future` function or the
 :meth:`BaseEventLoop.create_task` method with the coroutine object.
 
 .. seealso::

Doc/library/asyncio-eventloop.rst

@@ -36,7 +36,7 @@ Run an event loop
    Run until the :class:`Future` is done.
 
    If the argument is a :ref:`coroutine object <coroutine>`, it is wrapped by
-   :func:`async`.
+   :func:`ensure_future`.
 
    Return the Future's result, or raise its exception.
 

Doc/library/asyncio-protocol.rst

@@ -448,9 +448,9 @@ buffer size reaches the low-water mark.
 Coroutines and protocols
 ------------------------
 
-Coroutines can be scheduled in a protocol method using :func:`async`, but there
-is no guarantee made about the execution order.  Protocols are not aware of
-coroutines created in protocol methods and so will not wait for them.
+Coroutines can be scheduled in a protocol method using :func:`ensure_future`,
+but there is no guarantee made about the execution order.  Protocols are not
+aware of coroutines created in protocol methods and so will not wait for them.
 
 To have a reliable execution order, use :ref:`stream objects <asyncio-streams>` in a
 coroutine with ``yield from``. For example, the :meth:`StreamWriter.drain`

Doc/library/asyncio-task.rst

@@ -59,7 +59,7 @@ the coroutine object returned by the call doesn't do anything until you
 schedule its execution.  There are two basic ways to start it running:
 call ``await coroutine`` or ``yield from coroutine`` from another coroutine
 (assuming the other coroutine is already running!), or schedule its execution
-using the :func:`async` function or the :meth:`BaseEventLoop.create_task`
+using the :func:`ensure_future` function or the :meth:`BaseEventLoop.create_task`
 method.
 
 
@@ -85,7 +85,7 @@ Coroutines (and tasks) can only run when the event loop is running.
     even if they are plain Python functions returning a :class:`Future`.
     This is intentional to have a freedom of tweaking the implementation
     of these functions in the future. If such a function is needed to be
-    used in a callback-style code, wrap its result with :func:`async`.
+    used in a callback-style code, wrap its result with :func:`ensure_future`.
 
 
 .. _asyncio-hello-world-coroutine:
@@ -394,7 +394,7 @@ Task
    <coroutine>` did not complete. It is probably a bug and a warning is
    logged: see :ref:`Pending task destroyed <asyncio-pending-task-destroyed>`.
 
-   Don't directly create :class:`Task` instances: use the :func:`async`
+   Don't directly create :class:`Task` instances: use the :func:`ensure_future`
    function or the :meth:`BaseEventLoop.create_task` method.
 
    This class is :ref:`not thread safe <asyncio-multithreading>`.