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:mod:`uselect` -- wait for events on a set of streams
========================================================================
.. module:: uselect
:synopsis: wait for events on a set of streams
|see_cpython_module| :mod:`python:select`.
This module provides functions to efficiently wait for events on multiple
streams (select streams which are ready for operations).
Functions
---------
.. function:: poll()
Create an instance of the Poll class.
.. function:: select(rlist, wlist, xlist[, timeout])
Wait for activity on a set of objects.
This function is provided by some MicroPython ports for compatibility
and is not efficient. Usage of :class:`Poll` is recommended instead.
.. _class: Poll
class ``Poll``
--------------
Methods
~~~~~~~
.. method:: poll.register(obj[, eventmask])
Register *obj* for polling. *eventmask* is logical OR of:
* ``select.POLLIN`` - data available for reading
* ``select.POLLOUT`` - more data can be written
* ``select.POLLERR`` - error occurred
* ``select.POLLHUP`` - end of stream/connection termination detected
*eventmask* defaults to ``select.POLLIN | select.POLLOUT``.
.. method:: poll.unregister(obj)
Unregister *obj* from polling.
.. method:: poll.modify(obj, eventmask)
Modify the *eventmask* for *obj*.
.. method:: poll.poll([timeout])
Wait for at least one of the registered objects to become ready. Returns
list of (``obj``, ``event``, ...) tuples, ``event`` element specifies
which events happened with a stream and is a combination of ``select.POLL*``
constants described above. There may be other elements in tuple, depending
on a platform and version, so don't assume that its size is 2. In case of
timeout, an empty list is returned.
Timeout is in milliseconds.
.. admonition:: Difference to CPython
:class: attention
Tuples returned may contain more than 2 elements as described above.
.. method:: poll.ipoll(timeout=-1, flags=0)
Like :meth:`poll.poll`, but instead returns an iterator which yields
`callee-owned tuples`. This function provides efficient, allocation-free
way to poll on streams.
If *flags* is 1, one-shot behavior for events is employed: streams for
which events happened, event mask will be automatically reset (equivalent
to ``poll.modify(obj, 0)``), so new events for such a stream won't be
processed until new mask is set with `poll.modify()`. This behavior is
useful for asynchronous I/O schedulers.
.. admonition:: Difference to CPython
:class: attention
This function is a MicroPython extension.
|
