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avoid executing code in utils.localinterfaces at import time...
avoid executing code in utils.localinterfaces at import time moves away from global constants to utility functions. The code is still only executed once, but instead of at import time, it is executed at first request.

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logwatcher.py
117 lines | 3.8 KiB | text/x-python | PythonLexer
"""
A simple logger object that consolidates messages incoming from ipcluster processes.
Authors:
* MinRK
"""
#-----------------------------------------------------------------------------
# Copyright (C) 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 logging
import sys
import zmq
from zmq.eventloop import ioloop, zmqstream
from IPython.config.configurable import LoggingConfigurable
from IPython.utils.localinterfaces import localhost
from IPython.utils.traitlets import Int, Unicode, Instance, List
#-----------------------------------------------------------------------------
# Classes
#-----------------------------------------------------------------------------
class LogWatcher(LoggingConfigurable):
"""A simple class that receives messages on a SUB socket, as published
by subclasses of `zmq.log.handlers.PUBHandler`, and logs them itself.
This can subscribe to multiple topics, but defaults to all topics.
"""
# configurables
topics = List([''], config=True,
help="The ZMQ topics to subscribe to. Default is to subscribe to all messages")
url = Unicode(config=True,
help="ZMQ url on which to listen for log messages")
def _url_default(self):
return 'tcp://%s:20202' % localhost()
# internals
stream = Instance('zmq.eventloop.zmqstream.ZMQStream')
context = Instance(zmq.Context)
def _context_default(self):
return zmq.Context.instance()
loop = Instance(zmq.eventloop.ioloop.IOLoop)
def _loop_default(self):
return ioloop.IOLoop.instance()
def __init__(self, **kwargs):
super(LogWatcher, self).__init__(**kwargs)
s = self.context.socket(zmq.SUB)
s.bind(self.url)
self.stream = zmqstream.ZMQStream(s, self.loop)
self.subscribe()
self.on_trait_change(self.subscribe, 'topics')
def start(self):
self.stream.on_recv(self.log_message)
def stop(self):
self.stream.stop_on_recv()
def subscribe(self):
"""Update our SUB socket's subscriptions."""
self.stream.setsockopt(zmq.UNSUBSCRIBE, '')
if '' in self.topics:
self.log.debug("Subscribing to: everything")
self.stream.setsockopt(zmq.SUBSCRIBE, '')
else:
for topic in self.topics:
self.log.debug("Subscribing to: %r"%(topic))
self.stream.setsockopt(zmq.SUBSCRIBE, topic)
def _extract_level(self, topic_str):
"""Turn 'engine.0.INFO.extra' into (logging.INFO, 'engine.0.extra')"""
topics = topic_str.split('.')
for idx,t in enumerate(topics):
level = getattr(logging, t, None)
if level is not None:
break
if level is None:
level = logging.INFO
else:
topics.pop(idx)
return level, '.'.join(topics)
def log_message(self, raw):
"""receive and parse a message, then log it."""
if len(raw) != 2 or '.' not in raw[0]:
self.log.error("Invalid log message: %s"%raw)
return
else:
topic, msg = raw
# don't newline, since log messages always newline:
topic,level_name = topic.rsplit('.',1)
level,topic = self._extract_level(topic)
if msg[-1] == '\n':
msg = msg[:-1]
self.log.log(level, "[%s] %s" % (topic, msg))