Source code for linkcheck.cache.robots_txt

# Copyright (C) 2006-2014 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 robots.txt contents.
"""
from .. import robotparser2
from ..containers import LFUCache
from ..decorators import synchronized
from ..lock import get_lock


# lock objects
cache_lock = get_lock("robots.txt_cache_lock")
robot_lock = get_lock("robots.txt_robot_lock")


[docs]class RobotsTxt: """ Thread-safe cache of downloaded robots.txt files. format: {cache key (string) -> robots.txt content (RobotFileParser)} """ def __init__(self, useragent): """Initialize per-URL robots.txt cache.""" # mapping {URL -> parsed robots.txt} self.cache = LFUCache(size=100) self.hits = self.misses = 0 self.roboturl_locks = {} self.useragent = useragent
[docs] def allows_url(self, url_data, timeout=None): """Ask robots.txt allowance.""" roboturl = url_data.get_robots_txt_url() with self.get_lock(roboturl): return self._allows_url(url_data, roboturl, timeout)
def _allows_url(self, url_data, roboturl, timeout=None): """Ask robots.txt allowance. Assumes only single thread per robots.txt URL calls this function.""" with cache_lock: if roboturl in self.cache: self.hits += 1 rp = self.cache[roboturl] return rp.can_fetch(self.useragent, url_data.url) self.misses += 1 kwargs = dict(auth=url_data.auth, session=url_data.session, timeout=timeout) rp = robotparser2.RobotFileParser(**kwargs) rp.set_url(roboturl) rp.read() with cache_lock: self.cache[roboturl] = rp self.add_sitemap_urls(rp, url_data, roboturl) return rp.can_fetch(self.useragent, url_data.url)
[docs] def add_sitemap_urls(self, rp, url_data, roboturl): """Add sitemap URLs to queue.""" if not rp.sitemap_urls or not url_data.allows_simple_recursion(): return for sitemap_url, line in rp.sitemap_urls: url_data.add_url(sitemap_url, line=line)
[docs] @synchronized(robot_lock) def get_lock(self, roboturl): """Return lock for robots.txt url.""" return self.roboturl_locks.setdefault(roboturl, get_lock(roboturl))