1 files changed, 161 insertions, 0 deletions
diff --git a/zmq/sugar/poll.py b/zmq/sugar/poll.py
new file mode 100644
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+++ b/zmq/sugar/poll.py
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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' ]