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"""0MQ polling related functions and classes."""
# Copyright (C) PyZMQ Developers
# Distributed under the terms of the Modified BSD License.
import zmq
from zmq.backend import zmq_poll
from .constants import POLLIN, POLLOUT, POLLERR
#-----------------------------------------------------------------------------
# Polling related methods
#-----------------------------------------------------------------------------
class Poller(object):
"""A stateful poll interface that mirrors Python's built-in poll."""
sockets = None
_map = {}
def __init__(self):
self.sockets = []
self._map = {}
def __contains__(self, socket):
return socket in self._map
def register(self, socket, flags=POLLIN|POLLOUT):
"""p.register(socket, flags=POLLIN|POLLOUT)
Register a 0MQ socket or native fd for I/O monitoring.
register(s,0) is equivalent to unregister(s).
Parameters
----------
socket : zmq.Socket or native socket
A zmq.Socket or any Python object having a ``fileno()``
method that returns a valid file descriptor.
flags : int
The events to watch for. Can be POLLIN, POLLOUT or POLLIN|POLLOUT.
If `flags=0`, socket will be unregistered.
"""
if flags:
if socket in self._map:
idx = self._map[socket]
self.sockets[idx] = (socket, flags)
else:
idx = len(self.sockets)
self.sockets.append((socket, flags))
self._map[socket] = idx
elif socket in self._map:
# uregister sockets registered with no events
self.unregister(socket)
else:
# ignore new sockets with no events
pass
def modify(self, socket, flags=POLLIN|POLLOUT):
"""Modify the flags for an already registered 0MQ socket or native fd."""
self.register(socket, flags)
def unregister(self, socket):
"""Remove a 0MQ socket or native fd for I/O monitoring.
Parameters
----------
socket : Socket
The socket instance to stop polling.
"""
idx = self._map.pop(socket)
self.sockets.pop(idx)
# shift indices after deletion
for socket, flags in self.sockets[idx:]:
self._map[socket] -= 1
def poll(self, timeout=None):
"""Poll the registered 0MQ or native fds for I/O.
Parameters
----------
timeout : float, int
The timeout in milliseconds. If None, no `timeout` (infinite). This
is in milliseconds to be compatible with ``select.poll()``. The
underlying zmq_poll uses microseconds and we convert to that in
this function.
Returns
-------
events : list of tuples
The list of events that are ready to be processed.
This is a list of tuples of the form ``(socket, event)``, where the 0MQ Socket
or integer fd is the first element, and the poll event mask (POLLIN, POLLOUT) is the second.
It is common to call ``events = dict(poller.poll())``,
which turns the list of tuples into a mapping of ``socket : event``.
"""
if timeout is None or timeout < 0:
timeout = -1
elif isinstance(timeout, float):
timeout = int(timeout)
return zmq_poll(self.sockets, timeout=timeout)
def select(rlist, wlist, xlist, timeout=None):
"""select(rlist, wlist, xlist, timeout=None) -> (rlist, wlist, xlist)
Return the result of poll as a lists of sockets ready for r/w/exception.
This has the same interface as Python's built-in ``select.select()`` function.
Parameters
----------
timeout : float, int, optional
The timeout in seconds. If None, no timeout (infinite). This is in seconds to be
compatible with ``select.select()``. The underlying zmq_poll uses microseconds
and we convert to that in this function.
rlist : list of sockets/FDs
sockets/FDs to be polled for read events
wlist : list of sockets/FDs
sockets/FDs to be polled for write events
xlist : list of sockets/FDs
sockets/FDs to be polled for error events
Returns
-------
(rlist, wlist, xlist) : tuple of lists of sockets (length 3)
Lists correspond to sockets available for read/write/error events respectively.
"""
if timeout is None:
timeout = -1
# Convert from sec -> us for zmq_poll.
# zmq_poll accepts 3.x style timeout in ms
timeout = int(timeout*1000.0)
if timeout < 0:
timeout = -1
sockets = []
for s in set(rlist + wlist + xlist):
flags = 0
if s in rlist:
flags |= POLLIN
if s in wlist:
flags |= POLLOUT
if s in xlist:
flags |= POLLERR
sockets.append((s, flags))
return_sockets = zmq_poll(sockets, timeout)
rlist, wlist, xlist = [], [], []
for s, flags in return_sockets:
if flags & POLLIN:
rlist.append(s)
if flags & POLLOUT:
wlist.append(s)
if flags & POLLERR:
xlist.append(s)
return rlist, wlist, xlist
#-----------------------------------------------------------------------------
# Symbols to export
#-----------------------------------------------------------------------------
__all__ = [ 'Poller', 'select' ]
|
