mirror of
https://github.com/SickGear/SickGear.git
synced 2024-12-05 02:43:37 +00:00
cec4ed573d
Switched out sqlite3 libs in favour of SQLAlchemy v0.9, will gradually migrate dialects and scheme to be fully SQLAlchemy compliant for using there ORM with sessions instead of direct. Fixed getEpisode function to stop making unrequired scene number conversions on already converted data thats available now from cache.
470 lines
17 KiB
Python
470 lines
17 KiB
Python
"""
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CherryPy implements a simple caching system as a pluggable Tool. This tool
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tries to be an (in-process) HTTP/1.1-compliant cache. It's not quite there
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yet, but it's probably good enough for most sites.
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In general, GET responses are cached (along with selecting headers) and, if
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another request arrives for the same resource, the caching Tool will return 304
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Not Modified if possible, or serve the cached response otherwise. It also sets
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request.cached to True if serving a cached representation, and sets
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request.cacheable to False (so it doesn't get cached again).
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If POST, PUT, or DELETE requests are made for a cached resource, they
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invalidate (delete) any cached response.
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Usage
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=====
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Configuration file example::
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[/]
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tools.caching.on = True
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tools.caching.delay = 3600
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You may use a class other than the default
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:class:`MemoryCache<cherrypy.lib.caching.MemoryCache>` by supplying the config
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entry ``cache_class``; supply the full dotted name of the replacement class
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as the config value. It must implement the basic methods ``get``, ``put``,
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``delete``, and ``clear``.
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You may set any attribute, including overriding methods, on the cache
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instance by providing them in config. The above sets the
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:attr:`delay<cherrypy.lib.caching.MemoryCache.delay>` attribute, for example.
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"""
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import datetime
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import sys
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import threading
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import time
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import cherrypy
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from cherrypy.lib import cptools, httputil
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from cherrypy._cpcompat import copyitems, ntob, set_daemon, sorted, Event
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class Cache(object):
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"""Base class for Cache implementations."""
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def get(self):
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"""Return the current variant if in the cache, else None."""
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raise NotImplemented
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def put(self, obj, size):
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"""Store the current variant in the cache."""
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raise NotImplemented
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def delete(self):
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"""Remove ALL cached variants of the current resource."""
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raise NotImplemented
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def clear(self):
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"""Reset the cache to its initial, empty state."""
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raise NotImplemented
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# ------------------------------ Memory Cache ------------------------------- #
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class AntiStampedeCache(dict):
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"""A storage system for cached items which reduces stampede collisions."""
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def wait(self, key, timeout=5, debug=False):
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"""Return the cached value for the given key, or None.
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If timeout is not None, and the value is already
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being calculated by another thread, wait until the given timeout has
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elapsed. If the value is available before the timeout expires, it is
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returned. If not, None is returned, and a sentinel placed in the cache
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to signal other threads to wait.
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If timeout is None, no waiting is performed nor sentinels used.
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"""
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value = self.get(key)
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if isinstance(value, Event):
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if timeout is None:
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# Ignore the other thread and recalc it ourselves.
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if debug:
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cherrypy.log('No timeout', 'TOOLS.CACHING')
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return None
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# Wait until it's done or times out.
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if debug:
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cherrypy.log('Waiting up to %s seconds' %
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timeout, 'TOOLS.CACHING')
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value.wait(timeout)
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if value.result is not None:
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# The other thread finished its calculation. Use it.
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if debug:
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cherrypy.log('Result!', 'TOOLS.CACHING')
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return value.result
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# Timed out. Stick an Event in the slot so other threads wait
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# on this one to finish calculating the value.
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if debug:
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cherrypy.log('Timed out', 'TOOLS.CACHING')
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e = threading.Event()
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e.result = None
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dict.__setitem__(self, key, e)
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return None
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elif value is None:
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# Stick an Event in the slot so other threads wait
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# on this one to finish calculating the value.
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if debug:
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cherrypy.log('Timed out', 'TOOLS.CACHING')
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e = threading.Event()
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e.result = None
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dict.__setitem__(self, key, e)
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return value
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def __setitem__(self, key, value):
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"""Set the cached value for the given key."""
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existing = self.get(key)
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dict.__setitem__(self, key, value)
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if isinstance(existing, Event):
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# Set Event.result so other threads waiting on it have
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# immediate access without needing to poll the cache again.
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existing.result = value
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existing.set()
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class MemoryCache(Cache):
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"""An in-memory cache for varying response content.
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Each key in self.store is a URI, and each value is an AntiStampedeCache.
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The response for any given URI may vary based on the values of
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"selecting request headers"; that is, those named in the Vary
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response header. We assume the list of header names to be constant
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for each URI throughout the lifetime of the application, and store
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that list in ``self.store[uri].selecting_headers``.
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The items contained in ``self.store[uri]`` have keys which are tuples of
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request header values (in the same order as the names in its
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selecting_headers), and values which are the actual responses.
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"""
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maxobjects = 1000
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"""The maximum number of cached objects; defaults to 1000."""
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maxobj_size = 100000
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"""The maximum size of each cached object in bytes; defaults to 100 KB."""
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maxsize = 10000000
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"""The maximum size of the entire cache in bytes; defaults to 10 MB."""
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delay = 600
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"""Seconds until the cached content expires; defaults to 600 (10 minutes).
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"""
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antistampede_timeout = 5
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"""Seconds to wait for other threads to release a cache lock."""
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expire_freq = 0.1
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"""Seconds to sleep between cache expiration sweeps."""
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debug = False
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def __init__(self):
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self.clear()
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# Run self.expire_cache in a separate daemon thread.
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t = threading.Thread(target=self.expire_cache, name='expire_cache')
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self.expiration_thread = t
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set_daemon(t, True)
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t.start()
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def clear(self):
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"""Reset the cache to its initial, empty state."""
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self.store = {}
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self.expirations = {}
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self.tot_puts = 0
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self.tot_gets = 0
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self.tot_hist = 0
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self.tot_expires = 0
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self.tot_non_modified = 0
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self.cursize = 0
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def expire_cache(self):
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"""Continuously examine cached objects, expiring stale ones.
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This function is designed to be run in its own daemon thread,
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referenced at ``self.expiration_thread``.
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"""
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# It's possible that "time" will be set to None
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# arbitrarily, so we check "while time" to avoid exceptions.
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# See tickets #99 and #180 for more information.
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while time:
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now = time.time()
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# Must make a copy of expirations so it doesn't change size
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# during iteration
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for expiration_time, objects in copyitems(self.expirations):
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if expiration_time <= now:
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for obj_size, uri, sel_header_values in objects:
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try:
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del self.store[uri][tuple(sel_header_values)]
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self.tot_expires += 1
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self.cursize -= obj_size
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except KeyError:
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# the key may have been deleted elsewhere
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pass
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del self.expirations[expiration_time]
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time.sleep(self.expire_freq)
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def get(self):
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"""Return the current variant if in the cache, else None."""
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request = cherrypy.serving.request
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self.tot_gets += 1
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uri = cherrypy.url(qs=request.query_string)
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uricache = self.store.get(uri)
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if uricache is None:
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return None
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header_values = [request.headers.get(h, '')
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for h in uricache.selecting_headers]
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variant = uricache.wait(key=tuple(sorted(header_values)),
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timeout=self.antistampede_timeout,
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debug=self.debug)
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if variant is not None:
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self.tot_hist += 1
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return variant
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def put(self, variant, size):
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"""Store the current variant in the cache."""
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request = cherrypy.serving.request
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response = cherrypy.serving.response
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uri = cherrypy.url(qs=request.query_string)
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uricache = self.store.get(uri)
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if uricache is None:
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uricache = AntiStampedeCache()
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uricache.selecting_headers = [
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e.value for e in response.headers.elements('Vary')]
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self.store[uri] = uricache
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if len(self.store) < self.maxobjects:
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total_size = self.cursize + size
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# checks if there's space for the object
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if (size < self.maxobj_size and total_size < self.maxsize):
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# add to the expirations list
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expiration_time = response.time + self.delay
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bucket = self.expirations.setdefault(expiration_time, [])
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bucket.append((size, uri, uricache.selecting_headers))
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# add to the cache
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header_values = [request.headers.get(h, '')
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for h in uricache.selecting_headers]
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uricache[tuple(sorted(header_values))] = variant
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self.tot_puts += 1
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self.cursize = total_size
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def delete(self):
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"""Remove ALL cached variants of the current resource."""
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uri = cherrypy.url(qs=cherrypy.serving.request.query_string)
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self.store.pop(uri, None)
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def get(invalid_methods=("POST", "PUT", "DELETE"), debug=False, **kwargs):
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"""Try to obtain cached output. If fresh enough, raise HTTPError(304).
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If POST, PUT, or DELETE:
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* invalidates (deletes) any cached response for this resource
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* sets request.cached = False
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* sets request.cacheable = False
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else if a cached copy exists:
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* sets request.cached = True
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* sets request.cacheable = False
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* sets response.headers to the cached values
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* checks the cached Last-Modified response header against the
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current If-(Un)Modified-Since request headers; raises 304
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if necessary.
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* sets response.status and response.body to the cached values
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* returns True
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otherwise:
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* sets request.cached = False
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* sets request.cacheable = True
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* returns False
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"""
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request = cherrypy.serving.request
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response = cherrypy.serving.response
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if not hasattr(cherrypy, "_cache"):
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# Make a process-wide Cache object.
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cherrypy._cache = kwargs.pop("cache_class", MemoryCache)()
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# Take all remaining kwargs and set them on the Cache object.
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for k, v in kwargs.items():
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setattr(cherrypy._cache, k, v)
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cherrypy._cache.debug = debug
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# POST, PUT, DELETE should invalidate (delete) the cached copy.
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# See http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html#sec13.10.
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if request.method in invalid_methods:
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if debug:
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cherrypy.log('request.method %r in invalid_methods %r' %
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(request.method, invalid_methods), 'TOOLS.CACHING')
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cherrypy._cache.delete()
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request.cached = False
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request.cacheable = False
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return False
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if 'no-cache' in [e.value for e in request.headers.elements('Pragma')]:
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request.cached = False
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request.cacheable = True
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return False
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cache_data = cherrypy._cache.get()
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request.cached = bool(cache_data)
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request.cacheable = not request.cached
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if request.cached:
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# Serve the cached copy.
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max_age = cherrypy._cache.delay
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for v in [e.value for e in request.headers.elements('Cache-Control')]:
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atoms = v.split('=', 1)
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directive = atoms.pop(0)
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if directive == 'max-age':
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if len(atoms) != 1 or not atoms[0].isdigit():
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raise cherrypy.HTTPError(
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400, "Invalid Cache-Control header")
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max_age = int(atoms[0])
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break
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elif directive == 'no-cache':
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if debug:
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cherrypy.log(
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'Ignoring cache due to Cache-Control: no-cache',
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'TOOLS.CACHING')
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request.cached = False
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request.cacheable = True
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return False
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if debug:
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cherrypy.log('Reading response from cache', 'TOOLS.CACHING')
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s, h, b, create_time = cache_data
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age = int(response.time - create_time)
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if (age > max_age):
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if debug:
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cherrypy.log('Ignoring cache due to age > %d' % max_age,
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'TOOLS.CACHING')
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request.cached = False
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request.cacheable = True
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return False
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# Copy the response headers. See
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# https://bitbucket.org/cherrypy/cherrypy/issue/721.
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response.headers = rh = httputil.HeaderMap()
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for k in h:
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dict.__setitem__(rh, k, dict.__getitem__(h, k))
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# Add the required Age header
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response.headers["Age"] = str(age)
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try:
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# Note that validate_since depends on a Last-Modified header;
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# this was put into the cached copy, and should have been
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# resurrected just above (response.headers = cache_data[1]).
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cptools.validate_since()
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except cherrypy.HTTPRedirect:
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x = sys.exc_info()[1]
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if x.status == 304:
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cherrypy._cache.tot_non_modified += 1
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raise
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# serve it & get out from the request
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response.status = s
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response.body = b
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else:
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if debug:
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cherrypy.log('request is not cached', 'TOOLS.CACHING')
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return request.cached
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def tee_output():
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"""Tee response output to cache storage. Internal."""
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# Used by CachingTool by attaching to request.hooks
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request = cherrypy.serving.request
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if 'no-store' in request.headers.values('Cache-Control'):
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return
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def tee(body):
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"""Tee response.body into a list."""
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if ('no-cache' in response.headers.values('Pragma') or
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'no-store' in response.headers.values('Cache-Control')):
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for chunk in body:
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yield chunk
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return
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output = []
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for chunk in body:
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output.append(chunk)
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yield chunk
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# save the cache data
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body = ntob('').join(output)
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cherrypy._cache.put((response.status, response.headers or {},
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body, response.time), len(body))
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response = cherrypy.serving.response
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response.body = tee(response.body)
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def expires(secs=0, force=False, debug=False):
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"""Tool for influencing cache mechanisms using the 'Expires' header.
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secs
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Must be either an int or a datetime.timedelta, and indicates the
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number of seconds between response.time and when the response should
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expire. The 'Expires' header will be set to response.time + secs.
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If secs is zero, the 'Expires' header is set one year in the past, and
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the following "cache prevention" headers are also set:
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* Pragma: no-cache
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* Cache-Control': no-cache, must-revalidate
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force
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If False, the following headers are checked:
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* Etag
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* Last-Modified
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* Age
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* Expires
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If any are already present, none of the above response headers are set.
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"""
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response = cherrypy.serving.response
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headers = response.headers
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cacheable = False
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if not force:
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# some header names that indicate that the response can be cached
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for indicator in ('Etag', 'Last-Modified', 'Age', 'Expires'):
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if indicator in headers:
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cacheable = True
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break
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if not cacheable and not force:
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if debug:
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cherrypy.log('request is not cacheable', 'TOOLS.EXPIRES')
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else:
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if debug:
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cherrypy.log('request is cacheable', 'TOOLS.EXPIRES')
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if isinstance(secs, datetime.timedelta):
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secs = (86400 * secs.days) + secs.seconds
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if secs == 0:
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if force or ("Pragma" not in headers):
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headers["Pragma"] = "no-cache"
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if cherrypy.serving.request.protocol >= (1, 1):
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if force or "Cache-Control" not in headers:
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headers["Cache-Control"] = "no-cache, must-revalidate"
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# Set an explicit Expires date in the past.
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expiry = httputil.HTTPDate(1169942400.0)
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else:
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expiry = httputil.HTTPDate(response.time + secs)
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if force or "Expires" not in headers:
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headers["Expires"] = expiry
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