99 lines
3.4 KiB
Python
99 lines
3.4 KiB
Python
"""
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Caching framework.
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This package defines set of cache backends that all conform to a simple API.
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In a nutshell, a cache is a set of values -- which can be any object that
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may be pickled -- identified by string keys. For the complete API, see
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the abstract BaseCache class in django.core.cache.backends.base.
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Client code should not access a cache backend directly; instead it should
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either use the "cache" variable made available here, or it should use the
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get_cache() function made available here. get_cache() takes a backend URI
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(e.g. "memcached://127.0.0.1:11211/") and returns an instance of a backend
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cache class.
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See docs/cache.txt for information on the public API.
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"""
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try:
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# The mod_python version is more efficient, so try importing it first.
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from mod_python.util import parse_qsl
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except ImportError:
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try:
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# Python 2.6 and greater
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from urlparse import parse_qsl
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except ImportError:
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# Python 2.5, 2.4. Works on Python 2.6 but raises
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# PendingDeprecationWarning
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from cgi import parse_qsl
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from django.conf import settings
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from django.core import signals
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from django.core.cache.backends.base import InvalidCacheBackendError, CacheKeyWarning
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from django.utils import importlib
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# Name for use in settings file --> name of module in "backends" directory.
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# Any backend scheme that is not in this dictionary is treated as a Python
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# import path to a custom backend.
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BACKENDS = {
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'memcached': 'memcached',
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'locmem': 'locmem',
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'file': 'filebased',
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'db': 'db',
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'dummy': 'dummy',
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}
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def parse_backend_uri(backend_uri):
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"""
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Converts the "backend_uri" into a cache scheme ('db', 'memcached', etc), a
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host and any extra params that are required for the backend. Returns a
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(scheme, host, params) tuple.
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"""
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if backend_uri.find(':') == -1:
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raise InvalidCacheBackendError("Backend URI must start with scheme://")
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scheme, rest = backend_uri.split(':', 1)
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if not rest.startswith('//'):
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raise InvalidCacheBackendError("Backend URI must start with scheme://")
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host = rest[2:]
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qpos = rest.find('?')
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if qpos != -1:
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params = dict(parse_qsl(rest[qpos+1:]))
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host = rest[2:qpos]
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else:
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params = {}
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if host.endswith('/'):
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host = host[:-1]
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return scheme, host, params
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def get_cache(backend_uri, key_prefix=None, version=None, key_func=None):
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if key_prefix is None:
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key_prefix = settings.CACHE_KEY_PREFIX
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if version is None:
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version = settings.CACHE_VERSION
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if key_func is None:
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key_func = settings.CACHE_KEY_FUNCTION
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if key_func is not None and not callable(key_func):
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key_func_module_path, key_func_name = key_func.rsplit('.', 1)
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key_func_module = importlib.import_module(key_func_module_path)
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key_func = getattr(key_func_module, key_func_name)
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scheme, host, params = parse_backend_uri(backend_uri)
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if scheme in BACKENDS:
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name = 'django.core.cache.backends.%s' % BACKENDS[scheme]
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else:
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name = scheme
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module = importlib.import_module(name)
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return module.CacheClass(host, params, key_prefix=key_prefix, version=version, key_func=key_func)
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cache = get_cache(settings.CACHE_BACKEND)
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# Some caches -- python-memcached in particular -- need to do a cleanup at the
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# end of a request cycle. If the cache provides a close() method, wire it up
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# here.
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if hasattr(cache, 'close'):
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signals.request_finished.connect(cache.close)
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