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.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 Poll.for_events((self, 'r')).poll(timeout):
return self._receive_device()
else:
return None
def run(self):
self.monitor.start()
notifier = Poll.for_events(
(self.monitor, 'r'), (self._stop_event.source, 'r'))
while True:
for fd, event in notifier.poll():
if fd == 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 fd == self.monitor.fileno() and event == 'r':
read_device = partial(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')