From: Victor Stinner <victor.stinner@gmail.com>
Date: Sun, 31 Aug 2014 13:08:21 +0000 (+0200)
Subject: (Merge 3.4) asyncio, Tulip issue 205: Fix a race condition in
X-Git-Tag: v3.5.0a1~988
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=de993bd9b68f1a1c2a3208e2024c94f99eb6cd05;p=python

(Merge 3.4) asyncio, Tulip issue 205: Fix a race condition in
BaseSelectorEventLoop.sock_connect()

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.
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de993bd9b68f1a1c2a3208e2024c94f99eb6cd05