The call to `_untrack_reader` is performed too soon, causing the protocol
to forget about the reader before `connection_lost` can run and feed the
EOF to the reader. See bpo-35065.
The waiting is pretty normal for any asyncio program, logging its time just adds
a noise to logs without any useful information provided.
https://bugs.python.org/issue34849
* Insert the warn in the asyncio.sleep when the loop argument is used
* Insert the warn in the asyncio.wait and asyncio.wait_for when the loop argument is used
* Better format of the code
* Add news file
* change calls for get_event_loop() to calls for get_running_loop()
* Change message to be more clear in News
* Improve the comments in test_tasks
Store a weak reference to stream readerfor breaking strong references
It breaks the strong reference loop between reader and protocol and allows to detect and close the socket if the stream is deleted (garbage collected)
Various asyncio internals expect that the default executor is a
`ThreadPoolExecutor`, so deprecate passing anything else to
`loop.set_default_executor()`.
The cancellation of an overlapped WSARecv() has a race condition
which causes data loss because of the current implementation of
proactor in asyncio.
No longer cancel overlapped WSARecv() in _ProactorReadPipeTransport
to work around the race condition.
Remove the optimized recv_into() implementation to get simple
implementation of pause_reading() using the single _pending_data
attribute.
Move _feed_data_to_bufferred_proto() to protocols.py.
Remove set_protocol() method which became useless.
* Fix AttributeError (not all SSL exceptions have 'errno' attribute)
* Increase default handshake timeout from 10 to 60 seconds
* Make sure start_tls can be cancelled correctly
* Make sure any error in SSLProtocol gets propagated (instead of just being logged)
Future.set_result and Future.set_exception now raise InvalidStateError
if the futures are not pending or running. This mirrors the behavior
of asyncio.Future, and prevents AssertionErrors in asyncio.wrap_future
when set_result is called multiple times.
Currently, asyncio.wait_for(fut), upon reaching the timeout deadline,
cancels the future and returns immediately. This is problematic for
when *fut* is a Task, because it will be left running for an arbitrary
amount of time. This behavior is iself surprising and may lead to
related bugs such as the one described in bpo-33638:
condition = asyncio.Condition()
async with condition:
await asyncio.wait_for(condition.wait(), timeout=0.5)
Currently, instead of raising a TimeoutError, the above code will fail
with `RuntimeError: cannot wait on un-acquired lock`, because
`__aexit__` is reached _before_ `condition.wait()` finishes its
cancellation and re-acquires the condition lock.
To resolve this, make `wait_for` await for the task cancellation.
The tradeoff here is that the `timeout` promise may be broken if the
task decides to handle its cancellation in a slow way. This represents
a behavior change and should probably not be back-patched to 3.6 and
earlier.
Use transport.set_write_buffer_limits() in sendfile tests of
test_asyncio to make sure that the protocol is paused after sending
4 KiB. Previously,
test_sendfile_fallback_close_peer_in_the_middle_of_receiving() failed
on FreeBSD if the DATA was smaller than the default limit of 64 KiB.
Fix a race condition in SSLProtocol.connection_made() of
asyncio.sslproto: start immediately the handshake instead of using
call_soon(). Previously, data_received() could be called before the
handshake started, causing the handshake to hang or fail.
In this commit:
* Support BufferedProtocol in set_protocol() and start_tls()
* Fix proactor to cancel readers reliably
* Update tests to be compatible with OpenSSL 1.1.1
* Clarify BufferedProtocol docs
* Bump TLS tests timeouts to 60 seconds; eliminate possible race from start_serving
* Rewrite test_start_tls_server_1
* bpo-33263 Fix FD leak in _SelectorSocketTransport. (GH-6450)
Under particular circumstances _SelectorSocketTransport can try to add a reader
even the transport is already being closed. This can lead to FD leak and
invalid stated of the following connections. Fixed the SelectorSocketTransport
to add the reader only if the trasport is still active.
Fix typo from commit 6370f345e1
Signed-off-by: Christian Heimes <christian@python.org>
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# Pull Request title
It should be in the following format:
```
bpo-NNNN: Summary of the changes made
```
Where: bpo-NNNN refers to the issue number in the https://bugs.python.org.
Most PRs will require an issue number. Trivial changes, like fixing a typo, do not need an issue.
# Backport Pull Request title
If this is a backport PR (PR made against branches other than `master`),
please ensure that the PR title is in the following format:
```
[X.Y] <title from the original PR> (GH-NNNN)
```
Where: [X.Y] is the branch name, e.g. [3.6].
GH-NNNN refers to the PR number from `master`.
-->
<!-- issue-number: bpo-32262 -->
https://bugs.python.org/issue32262
<!-- /issue-number -->
Fix the following bugs in the C implementation:
* get_future_loop() silenced all exceptions raised when look up the get_loop
attribute, not just an AttributeError.
* enter_task() silenced all exceptions raised when look up the current task,
not just a KeyError.
* repr() was called for a borrowed link in enter_task() and task_step_impl().
* str() was used instead of repr() in formatting one error message (in
Python implementation too).
* There where few reference leaks in error cases.
The proactor event loop has a race condition when reading with
pausing/resuming. `resume_reading()` unconditionally schedules the read
function to read from the current future. If `resume_reading()` was
called before the previously scheduled done callback fires, this results
in two attempts to get the data from the most recent read and an
assertion failure. This commit tracks whether or not `resume_reading`
needs to reschedule the callback to restart the loop, preventing a
second attempt to read the data.
bpo-31399: Let OpenSSL verify hostname and IP
The ssl module now uses OpenSSL's X509_VERIFY_PARAM_set1_host() and
X509_VERIFY_PARAM_set1_ip() API to verify hostname and IP addresses.
* Remove match_hostname calls
* Check for libssl with set1_host, libssl must provide X509_VERIFY_PARAM_set1_host()
* Add documentation for OpenSSL 1.0.2 requirement
* Don't support OpenSSL special mode with a leading dot, e.g. ".example.org" matches "www.example.org". It's not standard conform.
* Add hostname_checks_common_name
Signed-off-by: Christian Heimes <christian@python.org>
* bpo-32662: Implement Server.start_serving() and Server.serve_forever()
New methods:
* Server.start_serving(),
* Server.serve_forever(), and
* Server.is_serving().
Add 'start_serving' keyword parameter to loop.create_server() and
loop.create_unix_server().
Specifically, it's not possible to subclass Task/Future classes
and override the following methods:
* Future._schedule_callbacks
* Task._step
* Task._wakeup
* Add coro.cr_origin and sys.set_coroutine_origin_tracking_depth
* Use coroutine origin information in the unawaited coroutine warning
* Stop using set_coroutine_wrapper in asyncio debug mode
* In BaseEventLoop.set_debug, enable debugging in the correct thread
* Make ssh_handshake_timeout None by default.
* Raise ValueError if ssl_handshake_timeout is used without ssl.
* Raise ValueError if ssl_handshake_timeout is not positive.
asyncio.get_event_loop(), and, subsequently asyncio._get_running_loop()
are one of the most frequently executed functions in asyncio. They also
can't be sped up by third-party event loops like uvloop.
When implemented in C they become 4x faster.
* 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
* bpo-32101: Add sys.flags.dev_mode flag
Rename also the "Developer mode" to the "Development mode".
* bpo-32101: Add PYTHONDEVMODE environment variable
Mention it in the development chapiter.
* Remove asyncio.selectors and asyncio._overlapped symbols from the
namespace of the asyncio module
* Replace "from asyncio import selectors" with "import selectors"
* Replace "from asyncio import _overlapped" with "import _overlapped"
asyncio.selectors was added to support Python 3.3, which doesn't have
selectors in its standard library, and Python 3.4 in the same code
base. Same rationale for asyncio._overlapped. Python 3.3 reached its
end of life, and asyncio is no more maintained as a third party
module on PyPI.
The asyncio/compat.py file was written to support Python < 3.5 and
Python < 3.5.2. But Python 3.5 doesn't accept bugfixes anymore, only
security fixes. There is no more need to backport bugfixes to Python
3.5, and so no need to have a single code base for Python 3.5, 3.6
and 3.7.
Say hello (again) to "async" and "await", who became real keywords in
Python 3.7 ;-)
* Explicitly call shutdown(wait=True) on executors to wait until all
threads complete to prevent side effects between tests.
* Fix test_loop_self_reading_exception(): don't mock loop.close().
Previously, the original close() method was called rather than the
mock, because how set_event_loop() registered loop.close().
* bpo-30280: asyncio now cleans up threads
asyncio base TestCase now uses threading_setup() and
threading_cleanup() of test.support to cleanup threads.
* asyncio: Fix TestBaseSelectorEventLoop cleanup
bpo-30280: TestBaseSelectorEventLoop of
test.test_asyncio.test_selector_events now correctly closes the event
loop: cleanup its executor to not leak threads.
Don't override the close() method of the event loop, only override
the_close_self_pipe() method.
when there are no more `await` or `yield (from)` before return in coroutine,
cancel was ignored.
example:
async def coro():
asyncio.Task.current_task().cancel()
return 42
...
res = await coro() # should raise CancelledError
Some built-in coroutine-like objects might not have __name__ or
__qualname__. A good example of such are 'asend', 'aclose' and
'athrow' coroutine methods of asynchronous generators.
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).
Issue #23749: With this change it's possible to implement starttls
as a separate package on PyPI, or even by copying/pasting a small
snipped of code in your project.
It's expected that we'll figure out the API design for starttls
during 3.6, so that we can add it in 3.7.
The deprecation include manual creation of SSLSocket and certfile/keyfile
(or similar) in ftplib, httplib, imaplib, smtplib, poplib and urllib.
ssl.wrap_socket() is not marked as deprecated yet.
This is now an official "protected" API that can be used to write
classes that are duck-type-compatible with Future without subclassing
it. (For that purpose I also changed isinstance(result, Future) to
check for this attribute instead.)
Hopefully Amber Brown can use this to make Twisted.Deferred compatible
with asyncio.Future.
Tests and docs are TBD. (Also there are more isinstance() checks to fix.)
This is now an official "protected" API that can be used to write
classes that are duck-type-compatible with Future without subclassing
it. (For that purpose I also changed isinstance(result, Future) to
check for this attribute instead.)
Hopefully Amber Brown can use this to make Twisted.Deferred compatible
with asyncio.Future.
Tests and docs are TBD.
Issue #26741: asyncio: BaseSubprocessTransport._process_exited() now copies the
return code from the child watched to the returncode attribute of the Popen
object. On Python 3.6, it is required to avoid a ResourceWarning.
Issue #26604:
* Add a new optional source parameter to _warnings.warn() and warnings.warn()
* Modify asyncore, asyncio and _pyio modules to set the source parameter when
logging a ResourceWarning warning
getaddrinfo takes an exclusive lock on some platforms, causing clients to queue
up waiting for the lock if many names are being resolved concurrently. Users
may want to handle name resolution in their own code, for the sake of caching,
using an alternate resolver, or to measure DNS duration separately from
connection duration. Skip getaddrinfo if the "host" passed into
create_connection is already resolved.
See https://github.com/python/asyncio/pull/302 for details.
Patch by A. Jesse Jiryu Davis.
This changes the main documentation, doc strings, source code comments, and a
couple error messages in the test suite. In some cases the word was removed
or edited some other way to fix the grammar.
This info is required on Python 3.5 and newer to get specific information on
the SSL object, like getting the binary peer certificate (instead of getting
it as text).
Issue #24763: Fix resource warnings when asyncio.BaseSubprocessTransport
constructor fails, if subprocess.Popen raises an exception for example.
Patch written by Martin Richard, test written by me.
* Fix ResourceWarning warnings in test_streams
* Return True from StreamReader.eof_received() to fix
http://bugs.python.org/issue24539 (but still needs a unittest).
Add StreamReader.__repr__() for easy debugging.
* remove unused imports
* Issue #234: Drop JoinableQueue on Python 3.5+
Previous approach of installing coroutine wrapper in loop.set_debug() and
uninstalling it in loop.close() was very fragile. Most of asyncio tests
do not call loop.close() at all. Since coroutine wrapper is a global
setting, we have to make sure that it's only set when the loop is
running, and is automatically unset when it stops running.
Issue #24017.
again if the first call to connect() raises an InterruptedError.
When the C function connect() fails with EINTR, the connection runs in
background. We have to wait until the socket becomes writable to be notified
when the connection succeed or fails.
Merge JoinableQueue with Queue. To more closely match the standard Queue,
asyncio.Queue has "join" and "task_done". JoinableQueue is deleted.
Docstring for Queue.join shouldn't mention threads.
Restore JoinableQueue as a deprecated alias for Queue. To more closely match
the standard Queue, asyncio.Queue has "join" and "task_done". JoinableQueue
remains as a deprecated alias for Queue to avoid needlessly breaking too much
code that depended on it.
Patch written by A. Jesse Jiryu Davis <jesse@mongodb.com>.
* _check_resolved_address() is implemented with getaddrinfo() which is slow
* If available, use socket.inet_pton() instead of socket.getaddrinfo(), because
it is much faster
Microbenchmark (timeit) on Fedora 21 (Python 3.4, Linux 3.17, glibc 2.20) to
validate the IPV4 address "127.0.0.1" or the IPv6 address "::1":
* getaddrinfo() 10.4 usec per loop
* inet_pton(): 0.285 usec per loop
On glibc older than 2.14, getaddrinfo() always requests the list of all local
IP addresses to the kernel (using a NETLINK socket). getaddrinfo() has other
known issues, it's better to avoid it when it is possible.
transport was closed. The check broken a Tulip example and this limitation is
arbitrary. Check if _proc is None should be enough.
Enhance also close(): do nothing when called the second time.
Issue #23347: send_signal(), kill() and terminate() methods of
BaseSubprocessTransport now check if the transport was closed and if the
process exited.
Issue #23347: Refactor creation of subprocess transports. Changes on
BaseSubprocessTransport:
* Add a wait() method to wait until the child process exit
* The constructor now accepts an optional waiter parameter. The _post_init()
coroutine must not be called explicitly anymore. It makes subprocess
transports closer to other transports, and it gives more freedom if we want
later to change completly how subprocess transports are created.
* close() now kills the process instead of kindly terminate it: the child
process may ignore SIGTERM and continue to run. Call explicitly terminate()
and wait() if you want to kindly terminate the child process.
* close() now logs a warning in debug mode if the process is still running and
needs to be killed
* _make_subprocess_transport() is now fully asynchronous again: if the creation
of the transport failed, wait asynchronously for the process eixt. Before the
wait was synchronous. This change requires close() to *kill*, and not
terminate, the child process.
* Remove the _kill_wait() method, replaced with a more agressive close()
method. It fixes _make_subprocess_transport() on error.
BaseSubprocessTransport.close() calls the close() method of pipe transports,
whereas _kill_wait() closed directly pipes of the subprocess.Popen object
without unregistering file descriptors from the selector (which caused severe
bugs).
These changes simplifies the code of subprocess.py.
* Cleanup gather(): use cancelled() method instead of using private Future
attribute
* Fix _UnixReadPipeTransport and _UnixWritePipeTransport. Only start reading
when connection_made() has been called.
* Issue #23333: Fix BaseSelectorEventLoop._accept_connection(). Close the
transport on error. In debug mode, log errors using call_exception_handler()
* _SelectorTransport constructor: extra parameter is now optional
* Fix _SelectorDatagramTransport constructor. Only start reading after
connection_made() has been called.
* Fix _SelectorSslTransport.close(). Don't call protocol.connection_lost() if
protocol.connection_made() was not called yet: if the SSL handshake failed or
is still in progress. The close() method can be called if the creation of the
connection is cancelled, by a timeout for example.
* Rephrase also the comment explaining why the waiter is not awaken immediatly.
* SSLProtocol.eof_received() doesn't instanciate ConnectionResetError exception
directly, it will be done by Future.set_exception(). The exception is not
used if the waiter was cancelled or if there is no waiter.
* Remove unused SSLProtocol._closing attribute
* test_sslproto: skip test if ssl module is missing
* Python issue #23208: Don't use the traceback of the current handle if we
already know the traceback of the source. The handle may be more revelant,
but having 3 tracebacks (handle, source, exception) becomes more difficult to
read. The handle may be preferred later but it requires more work to make
this choice.
If ReadFile() fails with ERROR_BROKEN_PIPE, the operation is not pending: don't
register the overlapped.
I don't know if WSARecv() can fail with ERROR_BROKEN_PIPE. Since
Overlapped.WSARecv() already handled ERROR_BROKEN_PIPE, let me guess that it
has the same behaviour than ReadFile().
If UnregisterWaitEx() fais with ERROR_IO_PENDING, it doesn't mean that the wait
is unregistered yet. We still have to wait until the wait is cancelled.
Use a coroutine with asyncio.sleep() instead of call_later() to ensure that the
schedule call is cancelled.
Add also a unit test cancelling connect_pipe().
In debug mode, BaseEventLoop._run_once() now sets the
BaseEventLoop._current_handle attribute to the handle currently executed.
In release mode or when no handle is executed, the attribute is None.
BaseEventLoop.default_exception_handler() displays the traceback of the current
handle if available.
Overlapped.ConnectNamedPipe() now returns a boolean: True if the pipe is
connected (if ConnectNamedPipe() failed with ERROR_PIPE_CONNECTED), False if
the connection is in progress.
This change removes multiple hacks in IocpProactor.
Add _overlapped.ConnectPipe() which tries to connect to the pipe for
asynchronous I/O (overlapped): call CreateFile() in a loop until it doesn't
fail with ERROR_PIPE_BUSY. Use an increasing delay between 1 ms and 100 ms.
Remove Overlapped.WaitNamedPipeAndConnect() which is no more used.
This change fixes a race conditon related to _WaitHandleFuture.cancel() leading
to Python crash or "GetQueuedCompletionStatus() returned an unexpected event"
logs. Before, the overlapped object was destroyed too early, it was possible
that the wait completed whereas the overlapped object was already destroyed.
Sometimes, a different overlapped was allocated at the same address, leading to
unexpected completition.
_WaitHandleFuture.cancel() now waits until the wait is cancelled to clear its
reference to the overlapped object. To wait until the cancellation is done,
UnregisterWaitEx() is used with an event instead of UnregisterWait().
To wait for this event, a new _WaitCancelFuture class was added. It's a
simplified version of _WaitCancelFuture. For example, its cancel() method calls
UnregisterWait(), not UnregisterWaitEx(). _WaitCancelFuture should not be
cancelled.
The overlapped object is kept alive in _WaitHandleFuture until the wait is
unregistered.
Other changes:
* Add _overlapped.UnregisterWaitEx()
* Remove fast-path in IocpProactor.wait_for_handle() to immediatly set the
result if the wait already completed. I'm not sure that it's safe to
call immediatly UnregisterWaitEx() before the completion was signaled.
* Add IocpProactor._unregistered() to forget an overlapped which may never be
signaled, but may be signaled for the next loop iteration. It avoids to
block forever IocpProactor.close() if a wait was cancelled, and it may also
avoid some "... unexpected event ..." warnings.
* Handle correctly CancelledError: just exit
* On error, log the exception and exit
Don't try to close the event loop, it is probably running and so it cannot be
closed.
StreamWriter: close() now clears the reference to the transport
StreamWriter now raises an exception if it is closed: write(), writelines(),
write_eof(), can_write_eof(), get_extra_info(), drain().
Don't call immediatly self._process_write_backlog() but schedule the call using
call_soon(). _on_handshake_complete() can be called indirectly from
_process_write_backlog(), and _process_write_backlog() is not reentrant.
* PipeHandle now uses None instead of -1 for a closed handle
* Sort imports in windows_utils.
* Fix test_events on Python older than 3.5. Skip SSL tests on the
ProactorEventLoop if ssl.MemoryIO is missing
* Fix BaseEventLoop._create_connection_transport(). Close the transport if the
creation of the transport (if the waiter) gets an exception.
* _ProactorBasePipeTransport now sets _sock to None when the transport is
closed.
* Fix BaseSubprocessTransport.close(). Ignore pipes for which the protocol is
not set yet (still equal to None).
* TestLoop.close() now calls the close() method of the parent class
(BaseEventLoop).
* Cleanup BaseSelectorEventLoop: create the protocol on a separated line for
readability and ease debugging.
* Fix BaseSubprocessTransport._kill_wait(). Set the _returncode attribute, so
close() doesn't try to terminate the process.
* Tests: explicitly close event loops and transports
* UNIX pipe transports: add closed/closing in repr(). Add "closed" or "closing"
state in the __repr__() method of _UnixReadPipeTransport and
_UnixWritePipeTransport classes.
* If an exception is raised during the creation of a subprocess, kill the
subprocess (close pipes, kill and read the return status). Log an error in
such case.
* Fix SubprocessStreamProtocol.connection_made() to handle cancelled waiter.
Add unit test cancelling subprocess methods.
- Add a new _wakeup_waiter() method
- Replace _create_waiter() method with a _wait_for_data() coroutine function
- Use the value None instead of True or False to wake up the waiter
The new SSL implementation is based on the new ssl.MemoryBIO which is only
available on Python 3.5. On Python 3.4 and older, the legacy SSL implementation
(using SSL_write, SSL_read, etc.) is used. The proactor event loop only
supports the new implementation.
The new asyncio.sslproto module adds _SSLPipe, SSLProtocol and
_SSLProtocolTransport classes. _SSLPipe allows to "wrap" or "unwrap" a socket
(switch between cleartext and SSL/TLS).
Patch written by Antoine Pitrou. sslproto.py is based on gruvi/ssl.py of the
gruvi project written by Geert Jansen.
This change adds SSL support to ProactorEventLoop on Python 3.5 and newer!
It becomes also possible to implement STARTTTLS: switch a cleartext socket to
SSL.
Close the IocpProactor before closing the event loop. IocpProactor.close() can
call loop.call_soon(), which is forbidden when the event loop is closed.
* Tulip issue 184: FlowControlMixin constructor now get the event loop if the
loop parameter is not set. Add unit tests to ensure that constructor of
StreamReader and StreamReaderProtocol classes get the event loop.
* Remove outdated TODO/XXX
* Document why set_result() calls are safe
* Cleanup gather(). Use public methods instead of hacks to consume the
exception of a future.
* sock_connect(): pass directly the fd to _sock_connect_done instead of the
socket.
asyncio.BaseEventLoop now use the identifier of the current thread to ensure
that they are called from the thread running the event loop.
Before, the get_event_loop() method was used to check the thread, and no
exception was raised when the thread had no event loop. Now the methods always
raise an exception in debug mode when called from the wrong thread. It should
help to notice misusage of the API.
* Fix a race condition in BaseSubprocessTransport._try_finish().
If the process exited before the _post_init() method was called, scheduling
the call to _call_connection_lost() with call_soon() is wrong:
connection_made() must be called before connection_lost().
Reuse the BaseSubprocessTransport._call() method to schedule the call to
_call_connection_lost() to ensure that connection_made() and
connection_lost() are called in the correct order.
* Add repr(PipeHandle)
* Fix typo
written by Torsten Landschoff.
create_task(), call_at(), call_soon(), call_soon_threadsafe() and
run_in_executor() now raise an error if the event loop is closed.
functions:
* add_signal_handler()
* call_at()
* call_later()
* call_soon()
* call_soon_threadsafe()
* run_in_executor()
Fix also the error message of add_signal_handler() (fix the name of the
function).
Move the _loop attribute from the constructor of _SelectorTransport,
_ProactorBasePipeTransport and _UnixWritePipeTransport classes to the
constructor of the _FlowControlMixin class.
Add also an assertion to explicit that the parent class must ensure that the
loop is defined (not None)
available
Since Python 3.5, socket.socketpair() is now also available on Windows.
Make csock blocking before calling the accept() method, and fix also a typo in
an error message.
There is a race condition in create_connection() used with wait_for() to have a
timeout. sock_connect() registers the file descriptor of the socket to be
notified of write event (if connect() raises BlockingIOError). When
create_connection() is cancelled with a TimeoutError, sock_connect() coroutine
gets the exception, but it doesn't unregister the file descriptor for write
event. create_connection() gets the TimeoutError and closes the socket.
If you call again create_connection(), the new socket will likely gets the same
file descriptor, which is still registered in the selector. When sock_connect()
calls add_writer(), it tries to modify the entry instead of creating a new one.
This issue was originally reported in the Trollius project, but the bug comes
from Tulip in fact (Trollius is based on Tulip):
https://bitbucket.org/enovance/trollius/issue/15/after-timeouterror-on-wait_for
This change fixes the race condition. It also makes sock_connect() more
reliable (and portable) is sock.connect() raises an InterruptedError.
Andrew Svetlov