Metadata-Version: 1.1
Name: django-calm-cache
Version: 0.9.2
Summary: A set of useful tools that enhance the standard Django cache experience
Home-page: https://bitbucket.org/pitcrews/django-calm-cache
Author: Fairfax Media
Author-email: opensource@pitcre.ws
License: BSD 3-Clause
Description: # Calm Cache for Django
        
        `django-calm-cache` keeps your cache calm while your site is being hammered by
        bucket loads of traffic.
        
        ## Key Features
        
         * [Mint caching](http://djangosnippets.org/snippets/155/) to avoid the
           [dog pile](http://en.wikipedia.org/wiki/Cache_stampede) effect
         * Timeout jitter to reduce the number of entries expiring simultaneously
         * Works alongside any other Django cache backend
         * `MemcachedCache` and `PyLibMCCache` Django backends are extended to support
           data compression provided by [python-memcached](ftp://ftp.tummy.com/pub/python-memcached/)
           and [pylibmc](http://sendapatch.se/projects/pylibmc/) respectively
         * `PyLibMCCache` is extended to support binary protocol
         * `cache_response` decorator that could be applied to any Django view and
           conditionally cache responses just like Django standard `CacheMiddleware`
           and `cache_page` do, but more configurable, explicit and extensible
        
        ## Installation
        
            :::shell
            pip install hg+https://bitbucket.org/pitcrews/django-calm-cache/
        
        
        ### Cache Backends
        
        Update the cache settings in your `settings.py`:
        
            :::python
            CACHES = {
                'default': {
                    'BACKEND' : 'calm_cache.backends.CalmCache',
                    'LOCATION': 'locmem-cache',
                    'KEY_FUNCTION': 'calm_cache.contrib.sha1_key_func',
                    'OPTIONS': {
                        'MINT_PERIOD': '10', # Allow stale results for this many seconds. Default: 0 (Off)
                        'GRACE_PERIOD': '120', # Serve stale value once during this period. Default: 0 (Off)
                        'JITTER': '10', # Upper bound on the random jitter in seconds. Default: 0 (Off)
                    },
                },
                'locmem-cache': {
                    'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
                    'LOCATION': 'foo',
                },
                'zipped-memcached': {
                    'BACKEND': 'calm_cache.backends.MemcachedCache',
                    'LOCATION': '127.0.0.1:11211',
                    'OPTIONS': {
                        'MIN_COMPRESS_LEN': 1024, # Compress values of this size or larger, bytes. Default: 0 (Disabled)
                    },
                },
                'zipped-bin-pylibmc': {
                    'BACKEND': 'calm_cache.backends.PyLibMCCache',
                    'LOCATION': '127.0.0.1:11211',
                    'OPTIONS': {
                        'MIN_COMPRESS_LEN': 1024, # Compress values of this size or larger, bytes. Default: 0 (Disabled)
                        'BINARY': True, # Enable binary protocol for this backend. Default: False (Disabled)
                    },
                },
            }
        
        Now relax knowing your site's caching won't fall over at the first sign of sustained traffic.
        
        #### CalmCache Configuration
        
        
        `LOCATION` parameter defines the name of another, "real", Django cache backend
        which will be used to actually store values
        
        `CalmCache` backend accepts the following options:
        
         * `MINT_PERIOD`: the time period that starts right after the user-supplied
           or default timeout (`TIMEOUT` setting) ends.
           First request during this period receives get() miss (`None` or default) and
           refreshes the value while all other requests are returning cached (stale)
           value until it is either updated or expired. Seconds. Default: `0`
         * `GRACE_PERIOD`: the time period starting after mint delay.
           During grace period stale value is returned only once and is removed after that.
           Seconds. Default: `0`
         * `JITTER`: defines the range for `[0 ... JITTER]` random value
           that is added to client supplied and "real" cache timeouts. Seconds. Default: `0`
        
        
        #### CalmCache Guidelines
        
        Actual stored key names are composed of `CalmCache.make_key()`
        and underlying cache's `make_key()` methods' outputs, and therefore are stacked:
        
            real_cache_prefix:calm_cache_prefix:user_supplied_key
        
        
        Minting is designed to cope with highly concurrent requests and good value
        of `MINT_PERIOD` would be comparable to the stored object regeneration time.
        
        Grace period starts after mint delay and first request that comes during this time
        is satisfied with stale value. The value cached under the given key
        is invalidated immediately and next requesting client will refresh and
        store a new value. This technique improves hit ratio for infrequently accessed
        data when occasional staleness is affordable.
        
        Add random variability to the expiry of cache objects as they may be generated
        at the same time, which mitigates expiry synchronisation
        
        The maximum real cache TTL is caclulated as
        
            timeout + MINT_PERIOD + GRACE_PERIOD + JITTER
        
        
        Setting `MINT_PERIOD`, `GRACE_PERIOD` or `JITTER` to `0` or not setting them
        at all turns off relevant logic in the code.
        
        
        #### CalmCache Limitations
        
         * `CalmCache` currently only supports cache methods `add`, `set`, `get`, `delete`,
           `has_key` and `clear`
        
        
        ### Response Cache
        
        Example usage:
        
            :::python
            from calm_cache.decorators import cache_response
        
            @cache_response(15, key_prefix='my_view', codes=(200, 404))
            def my_view(request, slug=None):
                return HttpResponse()
        
        `cache_response`'s constructor arguments, relevant Django settings and
        defaults:
        
         * `cache_timeout`: integer, default TTL for cached entries. Required
         * `cache`: Django cache backend name. If not specified, default cache
           backend will be used
         * `key_prefix`: this string is always prepending resulting keys.
           Default: `''`. Django setting: `CCRC_KEY_PREFIX`
         * `methods`: a list/tuple with request methods that could be cached.
           Default: `('GET', )`. Django setting: `CCRC_CACHE_REQ_METHDODS`
         * `codes`: a list/tuple with cacheable response codes.
           Default: `(200, )`. Django setting: `CCRC_CACHE_RSP_CODES`
         * `nocache_req`: a dictionary with request headers as keys and
           regular expressions as values (strings or compiled), so that when request
           has a header with value matching the expression,
           the response is never cached. The headers should be put in WSGI format,
           i.e. `'HTTP_X_FORWARDED_FOR'`. Default: `{}`.
         * `nocache_rsp`: a list of response headers that prevents response
           from being cached. Default: `('Set-Cookie', 'Vary')`.
           Django setting: `CCRC_NOCACHE_RSP_HEADERS`
         * `anonymous_only`: boolean selecting whether only anonymous requests
           should be served from the cache/responses cached.
           Default: `True`. Django setting: `CCRC_ANONYMOUS_REQ_ONLY`
         * `cache_cookies`: boolean, if False, requests with cookies will
           not be cached, otherwise cookies are ignored. Default: `False`.
           Django setting: `CCRC_CACHE_REQ_COOKIES`
         * `excluded_cookies`: if `cache_cookies` is False, cookies found in
           this list are ignored (considered as not set).
           If `cache_cookies` is True, response will not be cached if
           one of cookies listed is found in the request. Default: `()`.
           Django setting: `CCRC_EXCLUDED_REQ_COOKIES`
         * `include_scheme`: boolean selecting whether request scheme (http
           or https) should be used for the key. Default: `True`.
           Django setting: `CCRC_KEY_SCHEME`
         * `include_host`: boolean selecting whether requested Host: should
           be used for the key. Default: `True`. Django setting: `CCRC_KEY_HOST`
         * `hitmiss_header`: a tuple with three elements: header name,
           value for cache hit and another for cache miss.
           If set to `None`, the header is never added
           Default: `('X-Cache', 'Hit', 'Miss')'`. Django setting: `CCRC_HITMISS_HEADER`
         * `key_function`: optional callable that should be used instead of
           built-in key function.
           Has to accept request as its only argument and return either
           a string with the key or `None` if the request should not be cached.
        
        
        #### ResponseCache Features and Guidelines
        
         * Unlike `CacheMiddleware`, `cache_response` does not analyse `Cache-Control`
           header and does not change cache TTL. The header is cached along
           with the response just like any other header
         * Default settings for `cache_reponse` are chosen to be the safest, but in
           order to achieve better cache performance careful configuretion is required
         * By default, reponses with `Set-Cookie` and `Vary` headers are never cached,
           requests that have `Cookie` header are not cached either
         * Responses that have CSRF token(s) are never cached
         * Requests that have authenticated user associated with them are not cached
           by default
         * URL and Hostname are used to build the cache key, which could be a problem
           for certain caching engines due to their limitation to key characters and length.
           You are advised to use some hashing `KEY_FUNCTION` in your caching backend, like,
           for example, provided `calm_cache.contrib.sha1_key_func`
        
        
        ## Legals
        
        License: BSD 3-clause
        
        Copyright (c) 2014, Fairfax Media Limited
        All rights reserved.
        
Keywords: django cache memcache memcached minting pylibmc libmemcached
Platform: Platform Independent
Classifier: Development Status :: 4 - Beta
Classifier: Environment :: Web Environment
Classifier: Framework :: Django
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: BSD License
Classifier: Topic :: Internet :: WWW/HTTP
Classifier: Topic :: Internet :: WWW/HTTP :: Dynamic Content
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3.3
