def test_eintr_retry_call(tmpdir):
import os, signal, select
def handle_alarm(signum, frame):
# pylint: disable=unused-argument
pass
orig_alarm = signal.getsignal(signal.SIGALRM)
# Open an empty file and use it to wait for exceptions which should
# never happen
filename = tmpdir.join('test')
filename.ensure(file=True)
fd = os.open(str(filename), os.O_RDONLY)
try:
signal.signal(signal.SIGALRM, handle_alarm)
# Ensure that a signal raises EINTR on Python < 3.5
if sys.version_info < (3, 5):
with pytest.raises(select.error):
signal.alarm(1)
select.select([], [], [fd], 2)
# Ensure that wrapping the call does not raise EINTR
signal.alarm(1)
assert _util.eintr_retry_call(select.select, [], [], [3],
2) == ([], [], [])
finally:
os.close(fd)
signal.signal(signal.SIGALRM, orig_alarm)
def test_eintr_retry_call(tmpdir):
import os, signal, select
def handle_alarm(signum, frame):
pass
orig_alarm = signal.getsignal(signal.SIGALRM)
# Open an empty file and use it to wait for exceptions which should
# never happen
filename = tmpdir.join('test')
filename.ensure(file=True)
fd = os.open(str(filename), os.O_RDONLY)
try:
signal.signal(signal.SIGALRM, handle_alarm)
# Ensure that a signal raises EINTR on Python < 3.5
if sys.version_info < (3, 5):
with pytest.raises(select.error) as e:
signal.alarm(1)
select.select([], [], [fd], 2)
# Ensure that wrapping the call does not raise EINTR
signal.alarm(1)
assert _util.eintr_retry_call(select.select, [], [], [3], 2) == ([], [], [])
finally:
os.close(fd)
signal.signal(signal.SIGALRM, orig_alarm)
def send_stop(self):
"""
Send a stop signal to the background thread.
The background thread will eventually exit, but it may still be running
when this method returns. This method is essentially the asynchronous
equivalent to :meth:`stop()`.
.. note::
The underlying :attr:`monitor` is *not* stopped.
"""
if self._stop_event is None:
return
with self._stop_event.sink:
# emit a stop event to the thread
eintr_retry_call(self._stop_event.sink.write, b'\x01')
self._stop_event.sink.flush()
def send_stop(self):
"""
Send a stop signal to the background thread.
The background thread will eventually exit, but it may still be running
when this method returns. This method is essentially the asynchronous
equivalent to :meth:`stop()`.
.. note::
The underlying :attr:`monitor` is *not* stopped.
"""
if self._stop_event is None:
return
with self._stop_event.sink:
# emit a stop event to the thread
eintr_retry_call(self._stop_event.sink.write, b'\x01')
self._stop_event.sink.flush()
def poll(self, timeout=None):
"""
Poll for a device event.
You can use this method together with :func:`iter()` to synchronously
monitor events in the current thread::
for device in iter(monitor.poll, None):
print('{0.action} on {0.device_path}'.format(device))
Since this method will never return ``None`` if no ``timeout`` is
specified, this is effectively an endless loop. With
:func:`functools.partial()` you can also create a loop that only waits
for a specified time::
for device in iter(partial(monitor.poll, 3), None):
print('{0.action} on {0.device_path}'.format(device))
This loop will only wait three seconds for a new device event. If no
device event occurred after three seconds, the loop will exit.
``timeout`` is a floating point number that specifies a time-out in
seconds. If omitted or ``None``, this method blocks until a device
event is available. If ``0``, this method just polls and will never
block.
.. note::
This method implicitly calls :meth:`start()`.
Return the received :class:`Device`, or ``None`` if a timeout
occurred. Raise :exc:`~exceptions.EnvironmentError` if event retrieval
failed.
.. seealso::
:attr:`Device.action`
The action that created this event.
:attr:`Device.sequence_number`
The sequence number of this event.
.. versionadded:: 0.16
"""
if timeout is not None and timeout > 0:
# .poll() takes timeout in milliseconds
timeout = int(timeout * 1000)
self.start()
if eintr_retry_call(poll.Poll.for_events((self, 'r')).poll, timeout):
return self._receive_device()
else:
return None
def poll(self, timeout=None):
"""
Poll for a device event.
You can use this method together with :func:`iter()` to synchronously
monitor events in the current thread::
for device in iter(monitor.poll, None):
print('{0.action} on {0.device_path}'.format(device))
Since this method will never return ``None`` if no ``timeout`` is
specified, this is effectively an endless loop. With
:func:`functools.partial()` you can also create a loop that only waits
for a specified time::
for device in iter(partial(monitor.poll, 3), None):
print('{0.action} on {0.device_path}'.format(device))
This loop will only wait three seconds for a new device event. If no
device event occurred after three seconds, the loop will exit.
``timeout`` is a floating point number that specifies a time-out in
seconds. If omitted or ``None``, this method blocks until a device
event is available. If ``0``, this method just polls and will never
block.
.. note::
This method implicitly calls :meth:`start()`.
Return the received :class:`Device`, or ``None`` if a timeout
occurred. Raise :exc:`~exceptions.EnvironmentError` if event retrieval
failed.
.. seealso::
:attr:`Device.action`
The action that created this event.
:attr:`Device.sequence_number`
The sequence number of this event.
.. versionadded:: 0.16
"""
if timeout is not None and timeout > 0:
# .poll() takes timeout in milliseconds
timeout = int(timeout * 1000)
self.start()
if eintr_retry_call(poll.Poll.for_events((self, 'r')).poll, timeout):
return self._receive_device()
else:
return None
def for_events(cls, *events):
"""Listen for ``events``.
``events`` is a list of ``(fd, event)`` pairs, where ``fd`` is a file
descriptor or file object and ``event`` either ``'r'`` or ``'w'``. If
``r``, listen for whether that is ready to be read. If ``w``, listen
for whether the channel is ready to be written to.
"""
notifier = eintr_retry_call(select.poll)
for fd, event in events:
mask = cls._EVENT_TO_MASK.get(event)
if not mask:
raise ValueError('Unknown event type: {0!r}'.format(event))
notifier.register(fd, mask)
return cls(notifier)
def run(self):
self.monitor.start()
notifier = poll.Poll.for_events(
(self.monitor, 'r'), (self._stop_event.source, 'r'))
while True:
for file_descriptor, event in eintr_retry_call(notifier.poll):
if file_descriptor == self._stop_event.source.fileno():
# in case of a stop event, close our pipe side, and
# return from the thread
self._stop_event.source.close()
return
elif file_descriptor == self.monitor.fileno() and event == 'r':
read_device = partial(eintr_retry_call, self.monitor.poll, timeout=0)
for device in iter(read_device, None):
self._callback(device)
else:
raise EnvironmentError('Observed monitor hung up')
def run(self):
self.monitor.start()
notifier = Poll.for_events(
(self.monitor, 'r'), (self._stop_event.source, 'r'))
while True:
for file_descriptor, event in eintr_retry_call(notifier.poll):
if file_descriptor == self._stop_event.source.fileno():
# in case of a stop event, close our pipe side, and
# return from the thread
self._stop_event.source.close()
return
elif file_descriptor == self.monitor.fileno() and event == 'r':
read_device = partial(eintr_retry_call, self.monitor.poll, timeout=0)
for device in iter(read_device, None):
self._callback(device)
else:
raise EnvironmentError('Observed monitor hung up')
def poll(self, timeout=None):
"""Poll for events.
``timeout`` is an integer specifying how long to wait for events (in
milliseconds). If omitted, ``None`` or negative, wait until an event
occurs.
Return a list of all events that occurred before ``timeout``, where
each event is a pair ``(fd, event)``. ``fd`` is the integral file
descriptor, and ``event`` a string indicating the event type. If
``'r'``, there is data to read from ``fd``. If ``'w'``, ``fd`` is
writable without blocking now. If ``'h'``, the file descriptor was
hung up (i.e. the remote side of a pipe was closed).
"""
# Return a list to allow clients to determine whether there are any
# events at all with a simple truthiness test.
return list(self._parse_events(eintr_retry_call(self._notifier.poll, timeout)))
def run(self):
self.monitor.enable_receiving()
with closing(select.epoll()) as notifier:
# poll on the stop event fd
notifier.register(self._stop_event_source, select.EPOLLIN)
# and on the monitor
notifier.register(self.monitor, select.EPOLLIN)
while True:
for fd, _ in eintr_retry_call(notifier.poll):
if fd == self._stop_event_source:
# in case of a stop event, close our pipe side, and
# return from the thread
os.close(self._stop_event_source)
return
else:
event = self.monitor.receive_device()
if event:
action, device = event
self._handle_event(action, device)
def __iter__(self):
"""
Wait for incoming events and receive them upon arrival.
This methods implicitly calls :meth:`enable_receiving`, and starts
polling the :meth:`fileno` of this monitor. If a event comes in, it
receives the corresponding device and yields it to the caller.
The returned iterator is endless, and continues receiving devices
without ever stopping.
Yields ``(action, device)`` (see :meth:`receive_device` for a
description).
"""
self.enable_receiving()
with closing(select.epoll()) as notifier:
notifier.register(self, select.EPOLLIN)
while True:
events = eintr_retry_call(notifier.poll)
for event in events:
yield self.receive_device()
