selectors

Selectors module.

This module allows high-level and efficient I/O multiplexing, built upon the
`select` module primitives.

Classes

ABCMeta

Metaclass for defining Abstract Base Classes (ABCs).

        Use this metaclass to create an ABC.  An ABC can be subclassed
        directly, and then acts as a mix-in class.  You can also register
        unrelated concrete classes (even built-in classes) and unrelated
        ABCs as 'virtual subclasses' -- these and their descendants will
        be considered subclasses of the registering ABC by the built-in
        issubclass() function, but the registering ABC won't show up in
        their MRO (Method Resolution Order) nor will method
        implementations defined by the registering ABC be callable (not
        even via super()).

mro(self, /)

  Return a type's method resolution order.

register(cls, subclass)

  Register a virtual subclass of an ABC.

              Returns the subclass, to allow usage as a class decorator.

BaseSelector

Selector abstract base class.

    A selector supports registering file objects to be monitored for specific
    I/O events.

    A file object is a file descriptor or any object with a `fileno()` method.
    An arbitrary object can be attached to the file object, which can be used
    for example to store context information, a callback, etc.

    A selector can use various implementations (select(), poll(), epoll()...)
    depending on the platform. The default `Selector` class uses the most
    efficient implementation on the current platform.

close(self)

  Close the selector.

          This must be called to make sure that any underlying resource is freed.

get_key(self, fileobj)

  Return the key associated to a registered file object.

          Returns:
          SelectorKey for this file object

get_map(self)

  Return a mapping of file objects to selector keys.

modify(self, fileobj, events, data=None)

  Change a registered file object monitored events or attached data.

          Parameters:
          fileobj -- file object or file descriptor
          events  -- events to monitor (bitwise mask of EVENT_READ|EVENT_WRITE)
          data    -- attached data

          Returns:
          SelectorKey instance

          Raises:
          Anything that unregister() or register() raises

register(self, fileobj, events, data=None)

  Register a file object.

          Parameters:
          fileobj -- file object or file descriptor
          events  -- events to monitor (bitwise mask of EVENT_READ|EVENT_WRITE)
          data    -- attached data

          Returns:
          SelectorKey instance

          Raises:
          ValueError if events is invalid
          KeyError if fileobj is already registered
          OSError if fileobj is closed or otherwise is unacceptable to
                  the underlying system call (if a system call is made)

          Note:
          OSError may or may not be raised

select(self, timeout=None)

  Perform the actual selection, until some monitored file objects are
          ready or a timeout expires.

          Parameters:
          timeout -- if timeout > 0, this specifies the maximum wait time, in
                     seconds
                     if timeout <= 0, the select() call won't block, and will
                     report the currently ready file objects
                     if timeout is None, select() will block until a monitored
                     file object becomes ready

          Returns:
          list of (key, events) for ready file objects
          `events` is a bitwise mask of EVENT_READ|EVENT_WRITE

unregister(self, fileobj)

  Unregister a file object.

          Parameters:
          fileobj -- file object or file descriptor

          Returns:
          SelectorKey instance

          Raises:
          KeyError if fileobj is not registered

          Note:
          If fileobj is registered but has since been closed this does
          *not* raise OSError (even if the wrapped syscall does)

EpollSelector

Epoll-based selector.

close(self)

fileno(self)

get_key(self, fileobj)

  Return the key associated to a registered file object.

          Returns:
          SelectorKey for this file object

get_map(self)

modify(self, fileobj, events, data=None)

register(self, fileobj, events, data=None)

select(self, timeout=None)

unregister(self, fileobj)

EpollSelector

Epoll-based selector.

close(self)

fileno(self)

get_key(self, fileobj)

  Return the key associated to a registered file object.

          Returns:
          SelectorKey for this file object

get_map(self)

modify(self, fileobj, events, data=None)

register(self, fileobj, events, data=None)

select(self, timeout=None)

unregister(self, fileobj)

Mapping

A Mapping is a generic container for associating key/value
    pairs.

    This class provides concrete generic implementations of all
    methods except for __getitem__, __iter__, and __len__.

get(self, key, default=None)

  D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None.

items(self)

  D.items() -> a set-like object providing a view on D's items

keys(self)

  D.keys() -> a set-like object providing a view on D's keys

values(self)

  D.values() -> an object providing a view on D's values

PollSelector

Poll-based selector.

close(self)

get_key(self, fileobj)

  Return the key associated to a registered file object.

          Returns:
          SelectorKey for this file object

get_map(self)

modify(self, fileobj, events, data=None)

register(self, fileobj, events, data=None)

select(self, timeout=None)

unregister(self, fileobj)

SelectSelector

Select-based selector.

close(self)

get_key(self, fileobj)

  Return the key associated to a registered file object.

          Returns:
          SelectorKey for this file object

get_map(self)

modify(self, fileobj, events, data=None)

register(self, fileobj, events, data=None)

select(self, timeout=None)

unregister(self, fileobj)

SelectorKey

SelectorKey(fileobj, fd, events, data)

    Object used to associate a file object to its backing
    file descriptor, selected event mask, and attached data.

count(self, value, /)

  Return number of occurrences of value.

index(self, value, start=0, stop=9223372036854775807, /)

  Return first index of value.

  Raises ValueError if the value is not present.

data = _tuplegetter(3, 'Optional opaque data associated to this file object.\n    For example, this could be used to store a per-client session ID.')
  Optional opaque data associated to this file object.
      For example, this could be used to store a per-client session ID.

events = _tuplegetter(2, 'Events that must be waited for on this file object.')
  Events that must be waited for on this file object.

fd = _tuplegetter(1, 'Underlying file descriptor.')
  Underlying file descriptor.

fileobj = _tuplegetter(0, 'File object registered.')
  File object registered.

Functions

abstractmethod

abstractmethod(funcobj)

  A decorator indicating abstract methods.

      Requires that the metaclass is ABCMeta or derived from it.  A
      class that has a metaclass derived from ABCMeta cannot be
      instantiated unless all of its abstract methods are overridden.
      The abstract methods can be called using any of the normal
      'super' call mechanisms.  abstractmethod() may be used to declare
      abstract methods for properties and descriptors.

      Usage:

          class C(metaclass=ABCMeta):
              @abstractmethod
              def my_abstract_method(self, ...):
                  ...

namedtuple

namedtuple(typename, field_names, *, rename=False, defaults=None, module=None)

  Returns a new subclass of tuple with named fields.

      >>> Point = namedtuple('Point', ['x', 'y'])
      >>> Point.__doc__                   # docstring for the new class
      'Point(x, y)'
      >>> p = Point(11, y=22)             # instantiate with positional args or keywords
      >>> p[0] + p[1]                     # indexable like a plain tuple
      33
      >>> x, y = p                        # unpack like a regular tuple
      >>> x, y
      (11, 22)
      >>> p.x + p.y                       # fields also accessible by name
      33
      >>> d = p._asdict()                 # convert to a dictionary
      >>> d['x']
      11
      >>> Point(**d)                      # convert from a dictionary
      Point(x=11, y=22)
      >>> p._replace(x=100)               # _replace() is like str.replace() but targets named fields
      Point(x=100, y=22)

Other members

EVENT_READ = 1

EVENT_WRITE = 2

Modules

math

select

sys