bpo-32193: Convert asyncio to async/await usage (#4753)

* Convert asyncio/tasks.py to async/await

* Convert asyncio/queues.py to async/await

* Convert asyncio/test_utils.py to async/await

* Convert asyncio/base_subprocess.py to async/await

* Convert asyncio/subprocess.py to async/await

* Convert asyncio/streams.py to async/await

* Fix comments

* Convert asyncio/locks.py to async/await

* Convert asyncio.sleep to async def

* Add a comment

* Add missing news

* Convert stubs from AbstrctEventLoop to async functions

* Convert subprocess_shell/subprocess_exec

* Convert connect_read_pipe/connect_write_pip to async/await syntax

* Convert create_datagram_endpoint

* Convert create_unix_server/create_unix_connection

* Get rid of old style coroutines in unix_events.py

* Convert selector_events.py to async/await

* Convert wait_closed and create_connection

* Drop redundant line

* Convert base_events.py

* Code cleanup

* Drop redundant comments

* Fix indentation

* Add explicit tests for compatibility between old and new coroutines

* Convert windows event loop to use async/await

* Fix double awaiting of async function

* Convert asyncio/locks.py

* Improve docstring

* Convert tests to async/await

* Convert more tests

* Convert more tests

* Convert more tests

* Convert tests

* Improve test

1 files changed, 59 insertions, 69 deletions

diff --git a/Lib/asyncio/base_events.py b/Lib/asyncio/base_events.py
index ffdb50f..ab92a0b 100644
--- a/Lib/asyncio/base_events.py
+++ b/Lib/asyncio/base_events.py
@@ -33,7 +33,6 @@ from . import coroutines
 from . import events
 from . import futures
 from . import tasks
-from .coroutines import coroutine
 from .log import logger
 
 
@@ -220,13 +219,12 @@ class Server(events.AbstractServer):
             if not waiter.done():
                 waiter.set_result(waiter)
 
-    @coroutine
-    def wait_closed(self):
+    async def wait_closed(self):
         if self.sockets is None or self._waiters is None:
             return
         waiter = self._loop.create_future()
         self._waiters.append(waiter)
-        yield from waiter
+        await waiter
 
 
 class BaseEventLoop(events.AbstractEventLoop):
@@ -330,10 +328,9 @@ class BaseEventLoop(events.AbstractEventLoop):
         """Create write pipe transport."""
         raise NotImplementedError
 
-    @coroutine
-    def _make_subprocess_transport(self, protocol, args, shell,
-                                   stdin, stdout, stderr, bufsize,
-                                   extra=None, **kwargs):
+    async def _make_subprocess_transport(self, protocol, args, shell,
+                                         stdin, stdout, stderr, bufsize,
+                                         extra=None, **kwargs):
         """Create subprocess transport."""
         raise NotImplementedError
 
@@ -371,8 +368,7 @@ class BaseEventLoop(events.AbstractEventLoop):
 
         self._asyncgens.add(agen)
 
-    @coroutine
-    def shutdown_asyncgens(self):
+    async def shutdown_asyncgens(self):
         """Shutdown all active asynchronous generators."""
         self._asyncgens_shutdown_called = True
 
@@ -384,12 +380,11 @@ class BaseEventLoop(events.AbstractEventLoop):
         closing_agens = list(self._asyncgens)
         self._asyncgens.clear()
 
-        shutdown_coro = tasks.gather(
+        results = await tasks.gather(
             *[ag.aclose() for ag in closing_agens],
             return_exceptions=True,
             loop=self)
 
-        results = yield from shutdown_coro
         for result, agen in zip(results, closing_agens):
             if isinstance(result, Exception):
                 self.call_exception_handler({
@@ -671,10 +666,10 @@ class BaseEventLoop(events.AbstractEventLoop):
     def getnameinfo(self, sockaddr, flags=0):
         return self.run_in_executor(None, socket.getnameinfo, sockaddr, flags)
 
-    @coroutine
-    def create_connection(self, protocol_factory, host=None, port=None, *,
-                          ssl=None, family=0, proto=0, flags=0, sock=None,
-                          local_addr=None, server_hostname=None):
+    async def create_connection(self, protocol_factory, host=None, port=None,
+                                *, ssl=None, family=0,
+                                proto=0, flags=0, sock=None,
+                                local_addr=None, server_hostname=None):
         """Connect to a TCP server.
 
         Create a streaming transport connection to a given Internet host and
@@ -722,7 +717,7 @@ class BaseEventLoop(events.AbstractEventLoop):
             else:
                 f2 = None
 
-            yield from tasks.wait(fs, loop=self)
+            await tasks.wait(fs, loop=self)
 
             infos = f1.result()
             if not infos:
@@ -755,7 +750,7 @@ class BaseEventLoop(events.AbstractEventLoop):
                             continue
                     if self._debug:
                         logger.debug("connect %r to %r", sock, address)
-                    yield from self.sock_connect(sock, address)
+                    await self.sock_connect(sock, address)
                 except OSError as exc:
                     if sock is not None:
                         sock.close()
@@ -793,7 +788,7 @@ class BaseEventLoop(events.AbstractEventLoop):
                 raise ValueError(
                     'A Stream Socket was expected, got {!r}'.format(sock))
 
-        transport, protocol = yield from self._create_connection_transport(
+        transport, protocol = await self._create_connection_transport(
             sock, protocol_factory, ssl, server_hostname)
         if self._debug:
             # Get the socket from the transport because SSL transport closes
@@ -803,9 +798,8 @@ class BaseEventLoop(events.AbstractEventLoop):
                          sock, host, port, transport, protocol)
         return transport, protocol
 
-    @coroutine
-    def _create_connection_transport(self, sock, protocol_factory, ssl,
-                                     server_hostname, server_side=False):
+    async def _create_connection_transport(self, sock, protocol_factory, ssl,
+                                           server_hostname, server_side=False):
 
         sock.setblocking(False)
 
@@ -820,19 +814,18 @@ class BaseEventLoop(events.AbstractEventLoop):
             transport = self._make_socket_transport(sock, protocol, waiter)
 
         try:
-            yield from waiter
+            await waiter
         except:
             transport.close()
             raise
 
         return transport, protocol
 
-    @coroutine
-    def create_datagram_endpoint(self, protocol_factory,
-                                 local_addr=None, remote_addr=None, *,
-                                 family=0, proto=0, flags=0,
-                                 reuse_address=None, reuse_port=None,
-                                 allow_broadcast=None, sock=None):
+    async def create_datagram_endpoint(self, protocol_factory,
+                                       local_addr=None, remote_addr=None, *,
+                                       family=0, proto=0, flags=0,
+                                       reuse_address=None, reuse_port=None,
+                                       allow_broadcast=None, sock=None):
         """Create datagram connection."""
         if sock is not None:
             if not _is_dgram_socket(sock):
@@ -872,7 +865,7 @@ class BaseEventLoop(events.AbstractEventLoop):
                         assert isinstance(addr, tuple) and len(addr) == 2, (
                             '2-tuple is expected')
 
-                        infos = yield from _ensure_resolved(
+                        infos = await _ensure_resolved(
                             addr, family=family, type=socket.SOCK_DGRAM,
                             proto=proto, flags=flags, loop=self)
                         if not infos:
@@ -918,7 +911,7 @@ class BaseEventLoop(events.AbstractEventLoop):
                     if local_addr:
                         sock.bind(local_address)
                     if remote_addr:
-                        yield from self.sock_connect(sock, remote_address)
+                        await self.sock_connect(sock, remote_address)
                         r_addr = remote_address
                 except OSError as exc:
                     if sock is not None:
@@ -948,32 +941,30 @@ class BaseEventLoop(events.AbstractEventLoop):
                              remote_addr, transport, protocol)
 
         try:
-            yield from waiter
+            await waiter
         except:
             transport.close()
             raise
 
         return transport, protocol
 
-    @coroutine
-    def _create_server_getaddrinfo(self, host, port, family, flags):
-        infos = yield from _ensure_resolved((host, port), family=family,
-                                            type=socket.SOCK_STREAM,
-                                            flags=flags, loop=self)
+    async def _create_server_getaddrinfo(self, host, port, family, flags):
+        infos = await _ensure_resolved((host, port), family=family,
+                                       type=socket.SOCK_STREAM,
+                                       flags=flags, loop=self)
         if not infos:
             raise OSError('getaddrinfo({!r}) returned empty list'.format(host))
         return infos
 
-    @coroutine
-    def create_server(self, protocol_factory, host=None, port=None,
-                      *,
-                      family=socket.AF_UNSPEC,
-                      flags=socket.AI_PASSIVE,
-                      sock=None,
-                      backlog=100,
-                      ssl=None,
-                      reuse_address=None,
-                      reuse_port=None):
+    async def create_server(self, protocol_factory, host=None, port=None,
+                            *,
+                            family=socket.AF_UNSPEC,
+                            flags=socket.AI_PASSIVE,
+                            sock=None,
+                            backlog=100,
+                            ssl=None,
+                            reuse_address=None,
+                            reuse_port=None):
         """Create a TCP server.
 
         The host parameter can be a string, in that case the TCP server is bound
@@ -1011,7 +1002,7 @@ class BaseEventLoop(events.AbstractEventLoop):
             fs = [self._create_server_getaddrinfo(host, port, family=family,
                                                   flags=flags)
                   for host in hosts]
-            infos = yield from tasks.gather(*fs, loop=self)
+            infos = await tasks.gather(*fs, loop=self)
             infos = set(itertools.chain.from_iterable(infos))
 
             completed = False
@@ -1068,8 +1059,8 @@ class BaseEventLoop(events.AbstractEventLoop):
             logger.info("%r is serving", server)
         return server
 
-    @coroutine
-    def connect_accepted_socket(self, protocol_factory, sock, *, ssl=None):
+    async def connect_accepted_socket(self, protocol_factory, sock,
+                                      *, ssl=None):
         """Handle an accepted connection.
 
         This is used by servers that accept connections outside of
@@ -1082,7 +1073,7 @@ class BaseEventLoop(events.AbstractEventLoop):
             raise ValueError(
                 'A Stream Socket was expected, got {!r}'.format(sock))
 
-        transport, protocol = yield from self._create_connection_transport(
+        transport, protocol = await self._create_connection_transport(
             sock, protocol_factory, ssl, '', server_side=True)
         if self._debug:
             # Get the socket from the transport because SSL transport closes
@@ -1091,14 +1082,13 @@ class BaseEventLoop(events.AbstractEventLoop):
             logger.debug("%r handled: (%r, %r)", sock, transport, protocol)
         return transport, protocol
 
-    @coroutine
-    def connect_read_pipe(self, protocol_factory, pipe):
+    async def connect_read_pipe(self, protocol_factory, pipe):
         protocol = protocol_factory()
         waiter = self.create_future()
         transport = self._make_read_pipe_transport(pipe, protocol, waiter)
 
         try:
-            yield from waiter
+            await waiter
         except:
             transport.close()
             raise
@@ -1108,14 +1098,13 @@ class BaseEventLoop(events.AbstractEventLoop):
                          pipe.fileno(), transport, protocol)
         return transport, protocol
 
-    @coroutine
-    def connect_write_pipe(self, protocol_factory, pipe):
+    async def connect_write_pipe(self, protocol_factory, pipe):
         protocol = protocol_factory()
         waiter = self.create_future()
         transport = self._make_write_pipe_transport(pipe, protocol, waiter)
 
         try:
-            yield from waiter
+            await waiter
         except:
             transport.close()
             raise
@@ -1138,11 +1127,13 @@ class BaseEventLoop(events.AbstractEventLoop):
                 info.append('stderr=%s' % _format_pipe(stderr))
         logger.debug(' '.join(info))
 
-    @coroutine
-    def subprocess_shell(self, protocol_factory, cmd, *, stdin=subprocess.PIPE,
-                         stdout=subprocess.PIPE, stderr=subprocess.PIPE,
-                         universal_newlines=False, shell=True, bufsize=0,
-                         **kwargs):
+    async def subprocess_shell(self, protocol_factory, cmd, *,
+                               stdin=subprocess.PIPE,
+                               stdout=subprocess.PIPE,
+                               stderr=subprocess.PIPE,
+                               universal_newlines=False,
+                               shell=True, bufsize=0,
+                               **kwargs):
         if not isinstance(cmd, (bytes, str)):
             raise ValueError("cmd must be a string")
         if universal_newlines:
@@ -1157,17 +1148,16 @@ class BaseEventLoop(events.AbstractEventLoop):
             # (password) and may be too long
             debug_log = 'run shell command %r' % cmd
             self._log_subprocess(debug_log, stdin, stdout, stderr)
-        transport = yield from self._make_subprocess_transport(
+        transport = await self._make_subprocess_transport(
             protocol, cmd, True, stdin, stdout, stderr, bufsize, **kwargs)
         if self._debug:
             logger.info('%s: %r', debug_log, transport)
         return transport, protocol
 
-    @coroutine
-    def subprocess_exec(self, protocol_factory, program, *args,
-                        stdin=subprocess.PIPE, stdout=subprocess.PIPE,
-                        stderr=subprocess.PIPE, universal_newlines=False,
-                        shell=False, bufsize=0, **kwargs):
+    async def subprocess_exec(self, protocol_factory, program, *args,
+                              stdin=subprocess.PIPE, stdout=subprocess.PIPE,
+                              stderr=subprocess.PIPE, universal_newlines=False,
+                              shell=False, bufsize=0, **kwargs):
         if universal_newlines:
             raise ValueError("universal_newlines must be False")
         if shell:
@@ -1186,7 +1176,7 @@ class BaseEventLoop(events.AbstractEventLoop):
             # (password) and may be too long
             debug_log = 'execute program %r' % program
             self._log_subprocess(debug_log, stdin, stdout, stderr)
-        transport = yield from self._make_subprocess_transport(
+        transport = await self._make_subprocess_transport(
             protocol, popen_args, False, stdin, stdout, stderr,
             bufsize, **kwargs)
         if self._debug: