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 import signals

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

    22 from django.utils import importlib

    23 

    24 # Name for use in settings file --> name of module in "backends" directory.

    25 # Any backend scheme that is not in this dictionary is treated as a Python

    26 # import path to a custom backend.

    27 BACKENDS = {

    28     'memcached': 'memcached',

    29     'locmem': 'locmem',

    30     'file': 'filebased',

    31     'db': 'db',

    32     'dummy': 'dummy',

    33 }

    34 

    35 def parse_backend_uri(backend_uri):

    36     """

    37     Converts the "backend_uri" into a cache scheme ('db', 'memcached', etc), a

    38     host and any extra params that are required for the backend. Returns a

    39     (scheme, host, params) tuple.

    40     """

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

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

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

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

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

    46 

    47     host = rest[2:]

    48     qpos = rest.find('?')

    49     if qpos != -1:

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

    51         host = rest[2:qpos]

    52     else:

    53         params = {}

    54     if host.endswith('/'):

    55         host = host[:-1]

    56 

    57     return scheme, host, params

    58 

    59 def get_cache(backend_uri):

    60     scheme, host, params = parse_backend_uri(backend_uri)

    61     if scheme in BACKENDS:

    62         name = 'django.core.cache.backends.%s' % BACKENDS[scheme]

    63     else:

    64         name = scheme

    65     module = importlib.import_module(name)

    66     return getattr(module, 'CacheClass')(host, params)

    67 

    68 cache = get_cache(settings.CACHE_BACKEND)

    69 

    70 # Some caches -- pythont-memcached in particular -- need to do a cleanup at the

    71 # end of a request cycle. If the cache provides a close() method, wire it up

    72 # here.

    73 if hasattr(cache, 'close'):

    74     signals.request_finished.connect(cache.close)

    75