import email.utils
+from requests import Session, Request, Timeout, ConnectionError
+
+from sima import SOCKET_TIMEOUT, WAIT_BETWEEN_REQUESTS
+from sima.utils.utils import WSError, WSTimeout, WSHTTPError, Throttle
from .cache import DictCache
retval = dict(parts_with_args + parts_wo_args)
return retval
- def cached_request(self, url, headers):
+ def cached_request(self, request):
"""Return the cached resquest if available and fresh
"""
- cache_url = self.cache_url(url)
- cc = self.parse_cache_control(headers)
+ cache_url = self.cache_url(request.url)
+ cc = self.parse_cache_control(request.headers)
# non-caching states
no_cache = True if 'no-cache' in cc else False
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):
+ if request.headers.get(header, None) != original_headers.get(header):
return False
now = time.time()
resp.from_cache = True
return resp
- # we're not fresh.
- self.cache.delete(cache_url)
+ # 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:
+ request.headers['If-None-Match'] = resp.headers['ETag']
+
+ if 'last-modified' in resp.headers:
+ request.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.
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.
- if 'date' in resp.headers:
+ elif 'date' in resp.headers:
# cache when there is a max-age > 0
if cc_resp and cc_resp.get('max-age'):
if int(cc_resp['max-age']) > 0:
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(response.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
+
+
+class HttpClient:
+ def __init__(self, cache=None, stats=None):
+ """
+ Prepare http request
+ Use cached elements or proceed http request
+ """
+ self.stats = stats
+ self.controller = CacheController(cache)
+
+ def __call__(self, ress, payload):
+ req = Request('GET', ress, params=payload,).prepare()
+ if self.stats:
+ self.stats.update(total=self.stats.get('total')+1)
+ cached_response = self.controller.cached_request(req)
+ if cached_response:
+ if self.stats:
+ self.stats.update(ccontrol=self.stats.get('ccontrol')+1)
+ return cached_response
+ try:
+ return self.fetch_ws(req)
+ except Timeout:
+ raise WSTimeout('Failed to reach server within {0}s'.format(
+ SOCKET_TIMEOUT))
+ except ConnectionError as err:
+ raise WSError(err)
+
+ @Throttle(WAIT_BETWEEN_REQUESTS)
+ def fetch_ws(self, prepreq):
+ """fetch from web service"""
+ sess = Session()
+ resp = sess.send(prepreq, timeout=SOCKET_TIMEOUT)
+ if resp.status_code == 304:
+ self.stats.update(etag=self.stats.get('etag')+1)
+ resp = self.controller.update_cached_response(prepreq, resp)
+ elif resp.status_code != 200:
+ raise WSHTTPError('{0.status_code}: {0.reason}'.format(resp))
+ ratelimit = resp.headers.get('x-ratelimit-remaining', None)
+ if ratelimit and self.stats:
+ minrl = min(int(ratelimit), self.stats.get('minrl'))
+ self.stats.update(minrl=minrl)
+ self.controller.cache_response(resp.request, resp)
+ return resp
+
+# VIM MODLINE
+# vim: ai ts=4 sw=4 sts=4 expandtab