heartbeat.py

"""The client and server for a basic ping-pong style heartbeat.
"""

#-----------------------------------------------------------------------------
#  Copyright (C) 2008-2011  The IPython Development Team
#
#  Distributed under the terms of the BSD License.  The full license is in
#  the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------

#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

import errno
import os
import socket
from threading import Thread

import zmq

from jupyter_client.localinterfaces import localhost

#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------


class Heartbeat(Thread):
    "A simple ping-pong style heartbeat that runs in a thread."

    def __init__(self, context, addr=None):
        if addr is None:
            addr = ('tcp', localhost(), 0)
        Thread.__init__(self)
        self.context = context
        self.transport, self.ip, self.port = addr
        self.original_port = self.port
        if self.original_port == 0:
            self.pick_port()
        self.addr = (self.ip, self.port)
        self.daemon = True

    def pick_port(self):
        if self.transport == 'tcp':
            s = socket.socket()
            # '*' means all interfaces to 0MQ, which is '' to socket.socket
            s.bind(('' if self.ip == '*' else self.ip, 0))
            self.port = s.getsockname()[1]
            s.close()
        elif self.transport == 'ipc':
            self.port = 1
            while os.path.exists("%s-%s" % (self.ip, self.port)):
                self.port = self.port + 1
        else:
            raise ValueError("Unrecognized zmq transport: %s" % self.transport)
        return self.port

    def _try_bind_socket(self):
        c = ':' if self.transport == 'tcp' else '-'
        return self.socket.bind('%s://%s' % (self.transport, self.ip) + c + str(self.port))

    def _bind_socket(self):
        try:
            win_in_use = errno.WSAEADDRINUSE
        except AttributeError:
            win_in_use = None

        # Try up to 100 times to bind a port when in conflict to avoid
        # infinite attempts in bad setups
        max_attempts = 1 if self.original_port else 100
        for attempt in range(max_attempts):
            try:
                self._try_bind_socket()
            except zmq.ZMQError as ze:
                if attempt == max_attempts - 1:
                    raise
                # Raise if we have any error not related to socket binding
                if ze.errno != errno.EADDRINUSE and ze.errno != win_in_use:
                    raise
                # Raise if we have any error not related to socket binding
                if self.original_port == 0:
                    self.pick_port()
                else:
                    raise
            else:
                return

    def run(self):
        self.socket = self.context.socket(zmq.ROUTER)
        self.socket.linger = 1000
        try:
            self._bind_socket()
        except Exception:
            self.socket.close()
            raise

        while True:
            try:
                zmq.device(zmq.QUEUE, self.socket, self.socket)
            except zmq.ZMQError as e:
                if e.errno == errno.EINTR:
                    # signal interrupt, resume heartbeat
                    continue
                elif e.errno == zmq.ETERM:
                    # context terminated, close socket and exit
                    try:
                        self.socket.close()
                    except zmq.ZMQError:
                        # suppress further errors during cleanup
                        # this shouldn't happen, though
                        pass
                    break
                elif e.errno == zmq.ENOTSOCK:
                    # socket closed elsewhere, exit
                    break
                else:
                    raise
            else:
                break