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bpo-38323: Add guard clauses in MultiLoopChildWatcher. (#22756) 

This is a trivial refactor in preparation for a fix for bpo-38323.
This commit is contained in:
Chris Jerdonek 2020-12-16 09:50:25 -08:00 committed by GitHub
parent c590c2338e
commit 66d3b589c4
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1 changed files with 19 additions and 15 deletions
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34
Lib/asyncio/unix_events.py
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@ -1226,13 +1226,15 @@ class MultiLoopChildWatcher(AbstractChildWatcher):
def close(self):
self._callbacks.clear()
if self._saved_sighandler is not None:
handler = signal.getsignal(signal.SIGCHLD)
if handler != self._sig_chld:
logger.warning("SIGCHLD handler was changed by outside code")
else:
signal.signal(signal.SIGCHLD, self._saved_sighandler)
self._saved_sighandler = None
if self._saved_sighandler is None:
return
handler = signal.getsignal(signal.SIGCHLD)
if handler != self._sig_chld:
logger.warning("SIGCHLD handler was changed by outside code")
else:
signal.signal(signal.SIGCHLD, self._saved_sighandler)
self._saved_sighandler = None
def __enter__(self):
return self
@ -1259,15 +1261,17 @@ class MultiLoopChildWatcher(AbstractChildWatcher):
# The reason to do it here is that attach_loop() is called from
# unix policy only for the main thread.
# Main thread is required for subscription on SIGCHLD signal
if self._saved_sighandler is None:
self._saved_sighandler = signal.signal(signal.SIGCHLD, self._sig_chld)
if self._saved_sighandler is None:
logger.warning("Previous SIGCHLD handler was set by non-Python code, "
"restore to default handler on watcher close.")
self._saved_sighandler = signal.SIG_DFL
if self._saved_sighandler is not None:
return
# Set SA_RESTART to limit EINTR occurrences.
signal.siginterrupt(signal.SIGCHLD, False)
self._saved_sighandler = signal.signal(signal.SIGCHLD, self._sig_chld)
if self._saved_sighandler is None:
logger.warning("Previous SIGCHLD handler was set by non-Python code, "
"restore to default handler on watcher close.")
self._saved_sighandler = signal.SIG_DFL
# Set SA_RESTART to limit EINTR occurrences.
signal.siginterrupt(signal.SIGCHLD, False)
def _do_waitpid_all(self):
for pid in list(self._callbacks):