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