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67 lines
1.9 KiB
67 lines
1.9 KiB
:mod:`select` -- wait for events on a set of streams
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========================================================================
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.. module:: select
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:synopsis: wait for events on a set of streams
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This module provides functions to wait for events on streams (select streams
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which are ready for operations).
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Pyboard specifics
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-----------------
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Polling is an efficient way of waiting for read/write activity on multiple
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objects. Current objects that support polling are: :class:`pyb.UART`,
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:class:`pyb.USB_VCP`.
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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 for compatibility and is not efficient. Usage
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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 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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