1 """

     2 Caching framework.

     3 

     4 This package defines set of cache backends that all conform to a simple API.

     5 In a nutshell, a cache is a set of values -- which can be any object that

     6 may be pickled -- identified by string keys.  For the complete API, see

     7 the abstract BaseCache class in django.core.cache.backends.base.

     8 

     9 Client code should not access a cache backend directly; instead it should

    10 either use the "cache" variable made available here, or it should use the

    11 get_cache() function made available here. get_cache() takes a backend URI

    12 (e.g. "memcached://127.0.0.1:11211/") and returns an instance of a backend

    13 cache class.

    14 

    15 See docs/cache.txt for information on the public API.

    16 """

    17 

    18 from cgi import parse_qsl

    19 from django.conf import settings

    20 from django.core.cache.backends.base import InvalidCacheBackendError

    21 

    22 BACKENDS = {

    23     # name for use in settings file --> name of module in "backends" directory

    24     'memcached': 'memcached',

    25     'locmem': 'locmem',

    26     'file': 'filebased',

    27     'db': 'db',

    28     'dummy': 'dummy',

    29 }

    30 

    31 DEPRECATED_BACKENDS = {

    32     # deprecated backend --> replacement module

    33     'simple': 'locmem',

    34 }

    35 

    36 def get_cache(backend_uri):

    37     if backend_uri.find(':') == -1:

    38         raise InvalidCacheBackendError, "Backend URI must start with scheme://"

    39     scheme, rest = backend_uri.split(':', 1)

    40     if not rest.startswith('//'):

    41         raise InvalidCacheBackendError, "Backend URI must start with scheme://"

    42     if scheme in DEPRECATED_BACKENDS:

    43         import warnings

    44         warnings.warn("'%s' backend is deprecated. Use '%s' instead." % 

    45             (scheme, DEPRECATED_BACKENDS[scheme]), DeprecationWarning)

    46         scheme = DEPRECATED_BACKENDS[scheme]

    47     if scheme not in BACKENDS:

    48         raise InvalidCacheBackendError, "%r is not a valid cache backend" % scheme

    49 

    50     host = rest[2:]

    51     qpos = rest.find('?')

    52     if qpos != -1:

    53         params = dict(parse_qsl(rest[qpos+1:]))

    54         host = rest[2:qpos]

    55     else:

    56         params = {}

    57     if host.endswith('/'):

    58         host = host[:-1]

    59 

    60     cache_class = getattr(__import__('django.core.cache.backends.%s' % BACKENDS[scheme], {}, {}, ['']), 'CacheClass')

    61     return cache_class(host, params)

    62 

    63 cache = get_cache(settings.CACHE_BACKEND)