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mirror of https://github.com/moparisthebest/SickRage synced 2024-11-11 03:45:01 -05:00
SickRage/lib/cachecontrol/controller.py
echel0n 05410e2aa0 Switched TVDB/TVRage CacheHandlers to CacheControl.
Replaced urllib2 with requests for both TVDB and TVRage.
Updated cache cleanup code to process both TVDB and TVRage cache folders.
2014-03-14 10:15:39 -07:00

248 lines
8.6 KiB
Python

"""
The httplib2 algorithms ported for use with requests.
"""
import re
import calendar
import time
from cachecontrol.cache import DictCache
from cachecontrol.compat import parsedate_tz
URI = re.compile(r"^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?")
def parse_uri(uri):
"""Parses a URI using the regex given in Appendix B of RFC 3986.
(scheme, authority, path, query, fragment) = parse_uri(uri)
"""
groups = URI.match(uri).groups()
return (groups[1], groups[3], groups[4], groups[6], groups[8])
class CacheController(object):
"""An interface to see if request should cached or not.
"""
def __init__(self, cache=None, cache_etags=True):
self.cache = cache or DictCache()
self.cache_etags = cache_etags
def _urlnorm(self, uri):
"""Normalize the URL to create a safe key for the cache"""
(scheme, authority, path, query, fragment) = parse_uri(uri)
if not scheme or not authority:
raise Exception("Only absolute URIs are allowed. uri = %s" % uri)
authority = authority.lower()
scheme = scheme.lower()
if not path:
path = "/"
# Could do syntax based normalization of the URI before
# computing the digest. See Section 6.2.2 of Std 66.
request_uri = query and "?".join([path, query]) or path
scheme = scheme.lower()
defrag_uri = scheme + "://" + authority + request_uri
return defrag_uri
def cache_url(self, uri):
return self._urlnorm(uri)
def parse_cache_control(self, headers):
"""
Parse the cache control headers returning a dictionary with values
for the different directives.
"""
retval = {}
cc_header = 'cache-control'
if 'Cache-Control' in headers:
cc_header = 'Cache-Control'
if cc_header in headers:
parts = headers[cc_header].split(',')
parts_with_args = [
tuple([x.strip().lower() for x in part.split("=", 1)])
for part in parts if -1 != part.find("=")]
parts_wo_args = [(name.strip().lower(), 1)
for name in parts if -1 == name.find("=")]
retval = dict(parts_with_args + parts_wo_args)
return retval
def cached_request(self, url, headers):
cache_url = self.cache_url(url)
cc = self.parse_cache_control(headers)
# non-caching states
no_cache = True if 'no-cache' in cc else False
if 'max-age' in cc and cc['max-age'] == 0:
no_cache = True
# see if it is in the cache anyways
in_cache = self.cache.get(cache_url)
if no_cache or not in_cache:
return False
# It is in the cache, so lets see if it is going to be
# fresh enough
resp = self.cache.get(cache_url)
# Check our Vary header to make sure our request headers match
# up. We don't delete it from the though, we just don't return
# our cached value.
#
# NOTE: Because httplib2 stores raw content, it denotes
# headers that were sent in the original response by
# adding -varied-$name. We don't have to do that b/c we
# are storing the object which has a reference to the
# original request. If that changes, then I'd propose
# using the varied headers in the cache key to avoid the
# situation all together.
if 'vary' in resp.headers:
varied_headers = resp.headers['vary'].replace(' ', '').split(',')
original_headers = resp.request.headers
for header in varied_headers:
# If our headers don't match for the headers listed in
# the vary header, then don't use the cached response
if headers.get(header, None) != original_headers.get(header):
return False
now = time.time()
date = calendar.timegm(
parsedate_tz(resp.headers['date'])
)
current_age = max(0, now - date)
# TODO: There is an assumption that the result will be a
# requests response object. This may not be best since we
# could probably avoid instantiating or constructing the
# response until we know we need it.
resp_cc = self.parse_cache_control(resp.headers)
# determine freshness
freshness_lifetime = 0
if 'max-age' in resp_cc and resp_cc['max-age'].isdigit():
freshness_lifetime = int(resp_cc['max-age'])
elif 'expires' in resp.headers:
expires = parsedate_tz(resp.headers['expires'])
if expires is not None:
expire_time = calendar.timegm(expires) - date
freshness_lifetime = max(0, expire_time)
# determine if we are setting freshness limit in the req
if 'max-age' in cc:
try:
freshness_lifetime = int(cc['max-age'])
except ValueError:
freshness_lifetime = 0
if 'min-fresh' in cc:
try:
min_fresh = int(cc['min-fresh'])
except ValueError:
min_fresh = 0
# adjust our current age by our min fresh
current_age += min_fresh
# see how fresh we actually are
fresh = (freshness_lifetime > current_age)
if fresh:
# make sure we set the from_cache to true
resp.from_cache = True
return resp
# we're not fresh. If we don't have an Etag, clear it out
if 'etag' not in resp.headers:
self.cache.delete(cache_url)
if 'etag' in resp.headers:
headers['If-None-Match'] = resp.headers['ETag']
if 'last-modified' in resp.headers:
headers['If-Modified-Since'] = resp.headers['Last-Modified']
# return the original handler
return False
def add_headers(self, url):
resp = self.cache.get(url)
if resp and 'etag' in resp.headers:
return {'If-None-Match': resp.headers['etag']}
return {}
def cache_response(self, request, resp):
"""
Algorithm for caching requests.
This assumes a requests Response object.
"""
# From httplib2: Don't cache 206's since we aren't going to
# handle byte range requests
if resp.status_code not in [200, 203]:
return
cc_req = self.parse_cache_control(request.headers)
cc = self.parse_cache_control(resp.headers)
cache_url = self.cache_url(request.url)
# Delete it from the cache if we happen to have it stored there
no_store = cc.get('no-store') or cc_req.get('no-store')
if no_store and self.cache.get(cache_url):
self.cache.delete(cache_url)
# If we've been given an etag, then keep the response
if self.cache_etags and 'etag' in resp.headers:
self.cache.set(cache_url, resp)
# Add to the cache if the response headers demand it. If there
# is no date header then we can't do anything about expiring
# the cache.
elif 'date' in resp.headers:
# cache when there is a max-age > 0
if cc and cc.get('max-age'):
if int(cc['max-age']) > 0:
self.cache.set(cache_url, resp)
# If the request can expire, it means we should cache it
# in the meantime.
elif 'expires' in resp.headers:
if resp.headers['expires']:
self.cache.set(cache_url, resp)
def update_cached_response(self, request, response):
"""On a 304 we will get a new set of headers that we want to
update our cached value with, assuming we have one.
This should only ever be called when we've sent an ETag and
gotten a 304 as the response.
"""
cache_url = self.cache_url(request.url)
resp = self.cache.get(cache_url)
if not resp:
# we didn't have a cached response
return response
# did so lets update our headers
resp.headers.update(resp.headers)
# we want a 200 b/c we have content via the cache
request.status_code = 200
# update the request as it has the if-none-match header + any
# other headers that the server might have updated (ie Date,
# Cache-Control, Expires, etc.)
resp.request = request
# update our cache
self.cache.set(cache_url, resp)
# Let everyone know this was from the cache.
resp.from_cache = True
return resp