linkchecker/linkcheck/cache/addrinfo.py
Bastian Kleineidam 02a09dbb28 Add documentation.
2012-09-17 16:30:32 +02:00

79 lines
2.7 KiB
Python

# -*- coding: iso-8859-1 -*-
# Copyright (C) 2006-2012 Bastian Kleineidam
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
"""
Cache for DNS lookups.
"""
import socket
import sys
from .. import LinkCheckerError
from ..lock import get_lock
from ..containers import LFUCache
from ..decorators import synchronized
_lock = get_lock("addrinfo")
class AddrInfo(object):
def __init__(self):
"""Initialize address info cache and cache statistics."""
self.addrinfos = LFUCache(size=100)
self.misses = self.hits = 0
def getaddrinfo(self, host, port):
"""Determine address information for given host and port for
streaming sockets (SOCK_STREAM).
Already cached information is used."""
key = u"%s:%s" % (unicode(host), unicode(port))
if key in self.addrinfos:
self.hits += 1
value = self.addrinfos[key]
else:
self.misses += 1
# check if it's an ascii host
if isinstance(host, unicode):
try:
host = host.encode('ascii')
except UnicodeEncodeError:
pass
try:
value = socket.getaddrinfo(host, port, 0, socket.SOCK_STREAM)
except socket.error:
value = sys.exc_info()[1]
except UnicodeError, msg:
args = dict(host=host, msg=str(msg))
value = LinkCheckerError(_("could not parse host %(host)r: %(msg)s") % args)
self.addrinfos[key] = value
if isinstance(value, Exception):
raise value
return value
_addrinfo = AddrInfo()
@synchronized(_lock)
def getaddrinfo(host, port):
"""Determine address information for given host and port for
streaming sockets (SOCK_STREAM).
Already cached information is used."""
return _addrinfo.getaddrinfo(host, port)
@synchronized(_lock)
def getstats():
"""Get cache statistics.
@return: hits and misses
@rtype tuple(int, int)
"""
return _addrinfo.hits, _addrinfo.misses