django-webcache

django web caching app that supports throttling, expiration and compression.

This uses code from django 1.6 for throttling transactions. If you are using django 1.5 or lower you might get lucky enough to hit the race condition if there are concurrent requests. In this event, it will just skip the throttle on that lookup.

Install

pip install django-webcache

Usage

All variables except url have defaults that can be overridden in the settings.py file

from urlopen import cache
from urlopen import throttle
from urlopen import cache_and_throttle

Cache

cache(url[, data=postdata][, location="path"][, expires=n |, expires=(n,m)][, overwrite=False][, compression=False])

variable	type	description
url	string	The url to retrieve / cache
data	string	urlencoded POST data string
location	string	The directory to save the cached pages to
expires	integer or 2 item tuple of integers	Number of seconds until the cache expires, or a range from which a random number of seconds will be chosen for the expiration
overwrite	boolean	Retrieve url and cache even if cache already exists
compression	string	Compress the cache

Throttle

throttle(url[, data=postdata][, delay=n |, delay=(n,m)])

variable	type	description
url	string	The url to retrieve / cache
data	string	urlencoded POST data string
delay	integer or 2 item tuple of integers	Number of seconds to throttle, or a range from which a random number will be chosen to throttle

Cache and Throttle

cache_and_throttle(url[, data=postdata][, location="path"][, expires=n |, expires=(n,m)][, overwrite=False][, compression=False][, delay=n |, delay=(n,m)])

variable	type	description
url	string	The url to retrieve / cache
data	string	urlencoded POST data string
location	string	The directory to save the cached pages to
expires	integer or 2 item tuple of integers	Number of seconds until the cache expires, or a range from which a random number of seconds will be chosen for the expiration
overwrite	boolean	Retrieve url and cache even if cache already exists
compression	string	Compress the cache
delay	integer or 2 item tuple of integers	Number of seconds to throttle, or a range from which a random number of seconds will be chosen to throttle

Examples

import webcache.urlopen
import urllib

pyurl = "http://www.python.org/"

"""just caching"""
response = urlopen.cache(pyurl)

"""caching with post data"""
postdata = urllib.urlencode({"name": "value"})
response = urlopen.cache(pyurl, data=postdata)

"""cache and override default cache file directory"""
response = urlopen.cache(pyurl, location=self.path)

"""cache and override default expiration time in seconds"""
response = urlopen.cache(pyurl, expires=10)

"""cache and override default overwrite setting
   will overwrite old cache even if not expired"""
response = urlopen.cache(pyurl, overwrite=True)

"""cache and override default compression with gzip compression"""
response = urlopen.cache(pyurl, compression='gzip')

"""throttle will wait 10 seconds since the previous web page retrieval of something
   from the same site. For example http://www.python.org/about will throttle if
   another lookup of http://www.python.org exists in the last 10 seconds"""
response = urlopen.throttle(pyurl, delay=10)

"""throttle using random range"""
response = urlopen.throttle(pyurl, delay=(60, 120))

"""combination of cache and throttle"""
response = urlopen.cache_and_throttle(pyurl, location=self.path, delay=10)

Developed By

• Drew Thomson - drew@thomson.ninja

Special Thanks

• Staffan Malmgren
• His original code: http://code.activestate.com/recipes/491261-caching-and-throttling-for-urllib2/

License

The MIT License (MIT)

Copyright (c) 2013 Drew Thomson

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.