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Cache middleware. If enabled, each Django-powered page will be cached based on
URL. The canonical way to enable cache middleware is to set
``UpdateCacheMiddleware`` as your first piece of middleware, and
``FetchFromCacheMiddleware`` as the last::

    MIDDLEWARE = [
        'django.middleware.cache.UpdateCacheMiddleware',
        ...
        'django.middleware.cache.FetchFromCacheMiddleware'
    ]

This is counter-intuitive, but correct: ``UpdateCacheMiddleware`` needs to run
last during the response phase, which processes middleware bottom-up;
``FetchFromCacheMiddleware`` needs to run last during the request phase, which
processes middleware top-down.

The single-class ``CacheMiddleware`` can be used for some simple sites.
However, if any other piece of middleware needs to affect the cache key, you'll
need to use the two-part ``UpdateCacheMiddleware`` and
``FetchFromCacheMiddleware``. This'll most often happen when you're using
Django's ``LocaleMiddleware``.

More details about how the caching works:

* Only GET or HEAD-requests with status code 200 are cached.

* The number of seconds each page is stored for is set by the "max-age" section
  of the response's "Cache-Control" header, falling back to the
  CACHE_MIDDLEWARE_SECONDS setting if the section was not found.

* This middleware expects that a HEAD request is answered with the same response
  headers exactly like the corresponding GET request.

* When a hit occurs, a shallow copy of the original response object is returned
  from process_request.

* Pages will be cached based on the contents of the request headers listed in
  the response's "Vary" header.

* This middleware also sets ETag, Last-Modified, Expires and Cache-Control
  headers on the response object.

    )settings)DEFAULT_CACHE_ALIAScaches)get_cache_keyget_max_agehas_vary_headerlearn_cache_keypatch_response_headers)MiddlewareMixinc                       s2   e Zd ZdZd	 fdd	Zdd Zdd Z  ZS )
UpdateCacheMiddlewarea6  
    Response-phase cache middleware that updates the cache if the response is
    cacheable.

    Must be used as part of the two-part update/fetch cache middleware.
    UpdateCacheMiddleware must be the first piece of middleware in MIDDLEWARE
    so that it'll get called last during the response phase.
    Nc                    s:   t  | tj| _d | _tj| _tj| _	t
| j	 | _d S N)super__init__r   ZCACHE_MIDDLEWARE_SECONDScache_timeoutpage_timeoutCACHE_MIDDLEWARE_KEY_PREFIX
key_prefixCACHE_MIDDLEWARE_ALIAScache_aliasr   cacheselfget_response	__class__ ;/tmp/pip-unpacked-wheel-3jxiddxt/django/middleware/cache.pyr   B   s    zUpdateCacheMiddleware.__init__c                 C   s   t |do|jS )N_cache_update_cache)hasattrr   r   requestresponser   r   r   _should_update_cacheJ   s    z*UpdateCacheMiddleware._should_update_cachec                    s    ||s|S |js |jdkr$|S |js>|jr>t|dr>|S d|ddkrR|S jdkrt|dkrxj	ndkr|S t
| r|jdkrt||jjd	 t|d
rt|jr| fdd nj | |S )zSet the cache, if needed.)   i0  CookieprivatezCache-Controlr   Nr   r#   r   renderc                    s   j  | S r   )r   set)r	cache_keyr   timeoutr   r   <lambda>p       z8UpdateCacheMiddleware.process_response.<locals>.<lambda>)r"   Z	streamingstatus_codeZCOOKIEScookiesr   getr   r   r   r	   r   r   r   r   callabler'   Zadd_post_render_callbackr(   r   r   r*   r   process_responseM   s0    
z&UpdateCacheMiddleware.process_response)N)__name__
__module____qualname____doc__r   r"   r3   __classcell__r   r   r   r   r   7   s   
r   c                       s*   e Zd ZdZd fdd	Zdd Z  ZS )FetchFromCacheMiddlewarea!  
    Request-phase cache middleware that fetches a page from the cache.

    Must be used as part of the two-part update/fetch cache middleware.
    FetchFromCacheMiddleware must be the last piece of middleware in MIDDLEWARE
    so that it'll get called last during the request phase.
    Nc                    s,   t  | tj| _tj| _t| j | _d S r   )	r   r   r   r   r   r   r   r   r   r   r   r   r   r      s    z!FetchFromCacheMiddleware.__init__c                 C   s   |j dkrd|_dS t|| jd| jd}|dkr:d|_dS | j|}|dkrx|j dkrxt|| jd| jd}| j|}|dkrd|_dS d|_|S )zn
        Check whether the page is already cached and return the cached
        version if available.
        )GETHEADFNr:   r&   Tr;   )methodr   r   r   r   r1   )r   r    r+   r!   r   r   r   process_request   s     
z(FetchFromCacheMiddleware.process_request)N)r4   r5   r6   r7   r   r=   r8   r   r   r   r   r9   w   s   	r9   c                       s"   e Zd ZdZd fdd	Z  ZS )CacheMiddlewarez
    Cache middleware that provides basic behavior for many simple sites.

    Also used as the hook point for the cache decorator, which is generated
    using the decorator-from-middleware utility.
    Nc                    s   t  | z|d }|d kr"d}|| _W n tk
r>   Y nX z*|d }|d krVt}|| _t| j | _W n tk
r~   Y nX |d k	r|| _|| _	d S )Nr    r   )
r   r   r   KeyErrorr   r   r   r   r   r   )r   r   r   r   kwargsr   r   r   r   r   r      s&    
zCacheMiddleware.__init__)NNN)r4   r5   r6   r7   r   r8   r   r   r   r   r>      s   r>   N)r7   Zdjango.confr   Zdjango.core.cacher   r   Zdjango.utils.cacher   r   r   r   r	   Zdjango.utils.deprecationr
   r   r9   r>   r   r   r   r   <module>   s   -@-