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"""Cache object
The Cache object is used to manage a set of cache files and their
associated backend. The backends can be rotated on the fly by
specifying an alternate type when used.
Advanced users can add new backends in beaker.backends
"""
import warnings
import beaker.container as container
import beaker.util as util
from beaker.exceptions import BeakerException, InvalidCacheBackendError
import beaker.ext.memcached as memcached
import beaker.ext.database as database
import beaker.ext.sqla as sqla
import beaker.ext.google as google
# Initialize the basic available backends
clsmap = {
'memory':container.MemoryNamespaceManager,
'dbm':container.DBMNamespaceManager,
'file':container.FileNamespaceManager,
'ext:memcached':memcached.MemcachedNamespaceManager,
'ext:database':database.DatabaseNamespaceManager,
'ext:sqla': sqla.SqlaNamespaceManager,
'ext:google': google.GoogleNamespaceManager,
}
# Initialize the cache region dict
cache_regions = {}
cache_managers = {}
try:
import pkg_resources
# Load up the additional entry point defined backends
for entry_point in pkg_resources.iter_entry_points('beaker.backends'):
try:
NamespaceManager = entry_point.load()
name = entry_point.name
if name in clsmap:
raise BeakerException("NamespaceManager name conflict,'%s' "
"already loaded" % name)
clsmap[name] = NamespaceManager
except (InvalidCacheBackendError, SyntaxError):
# Ignore invalid backends
pass
except:
import sys
from pkg_resources import DistributionNotFound
# Warn when there's a problem loading a NamespaceManager
if not isinstance(sys.exc_info()[1], DistributionNotFound):
import traceback
from StringIO import StringIO
tb = StringIO()
traceback.print_exc(file=tb)
warnings.warn("Unable to load NamespaceManager entry point: '%s': "
"%s" % (entry_point, tb.getvalue()), RuntimeWarning,
2)
except ImportError:
pass
def cache_region(region, *deco_args):
"""Decorate a function to cache itself using a cache region
The region decorator requires arguments if there are more than
2 of the same named function, in the same module. This is
because the namespace used for the functions cache is based on
the functions name and the module.
Example::
# Add cache region settings to beaker:
beaker.cache.cache_regions.update(dict_of_config_region_options))
@cache_region('short_term', 'some_data')
def populate_things(search_term, limit, offset):
return load_the_data(search_term, limit, offset)
return load('rabbits', 20, 0)
.. note::
The function being decorated must only be called with
positional arguments.
"""
cache = [None]
def decorate(func):
namespace = util.func_namespace(func)
def cached(*args):
reg = cache_regions[region]
if not reg.get('enabled', True):
return func(*args)
if not cache[0]:
if region not in cache_regions:
raise BeakerException('Cache region not configured: %s' % region)
cache[0] = Cache._get_cache(namespace, reg)
cache_key = " ".join(map(str, deco_args + args))
def go():
return func(*args)
return cache[0].get_value(cache_key, createfunc=go)
cached._arg_namespace = namespace
cached._arg_region = region
return cached
return decorate
def region_invalidate(namespace, region, *args):
"""Invalidate a cache region namespace or decorated function
This function only invalidates cache spaces created with the
cache_region decorator.
:param namespace: Either the namespace of the result to invalidate, or the
cached function reference
:param region: The region the function was cached to. If the function was
cached to a single region then this argument can be None
:param args: Arguments that were used to differentiate the cached
function as well as the arguments passed to the decorated
function
Example::
# Add cache region settings to beaker:
beaker.cache.cache_regions.update(dict_of_config_region_options))
def populate_things(invalidate=False):
@cache_region('short_term', 'some_data')
def load(search_term, limit, offset):
return load_the_data(search_term, limit, offset)
# If the results should be invalidated first
if invalidate:
region_invalidate(load, None, 'some_data',
'rabbits', 20, 0)
return load('rabbits', 20, 0)
"""
if callable(namespace):
if not region:
region = namespace._arg_region
namespace = namespace._arg_namespace
if not region:
raise BeakerException("Region or callable function "
"namespace is required")
else:
region = cache_regions[region]
cache = Cache._get_cache(namespace, region)
cache_key = " ".join(str(x) for x in args)
cache.remove_value(cache_key)
class Cache(object):
"""Front-end to the containment API implementing a data cache.
:param namespace: the namespace of this Cache
:param type: type of cache to use
:param expire: seconds to keep cached data
:param expiretime: seconds to keep cached data (legacy support)
:param starttime: time when cache was cache was
"""
def __init__(self, namespace, type='memory', expiretime=None,
starttime=None, expire=None, **nsargs):
try:
cls = clsmap[type]
if isinstance(cls, InvalidCacheBackendError):
raise cls
except KeyError:
raise TypeError("Unknown cache implementation %r" % type)
self.namespace = cls(namespace, **nsargs)
self.expiretime = expiretime or expire
self.starttime = starttime
self.nsargs = nsargs
@classmethod
def _get_cache(cls, namespace, kw):
key = namespace + str(kw)
try:
return cache_managers[key]
except KeyError:
cache_managers[key] = cache = cls(namespace, **kw)
return cache
def put(self, key, value, **kw):
self._get_value(key, **kw).set_value(value)
set_value = put
def get(self, key, **kw):
"""Retrieve a cached value from the container"""
return self._get_value(key, **kw).get_value()
get_value = get
def remove_value(self, key, **kw):
mycontainer = self._get_value(key, **kw)
if mycontainer.has_current_value():
mycontainer.clear_value()
remove = remove_value
def _get_value(self, key, **kw):
if isinstance(key, unicode):
key = key.encode('ascii', 'backslashreplace')
if 'type' in kw:
return self._legacy_get_value(key, **kw)
kw.setdefault('expiretime', self.expiretime)
kw.setdefault('starttime', self.starttime)
return container.Value(key, self.namespace, **kw)
@util.deprecated("Specifying a "
"'type' and other namespace configuration with cache.get()/put()/etc. "
"is deprecated. Specify 'type' and other namespace configuration to "
"cache_manager.get_cache() and/or the Cache constructor instead.")
def _legacy_get_value(self, key, type, **kw):
expiretime = kw.pop('expiretime', self.expiretime)
starttime = kw.pop('starttime', None)
createfunc = kw.pop('createfunc', None)
kwargs = self.nsargs.copy()
kwargs.update(kw)
c = Cache(self.namespace.namespace, type=type, **kwargs)
return c._get_value(key, expiretime=expiretime, createfunc=createfunc,
starttime=starttime)
def clear(self):
"""Clear all the values from the namespace"""
self.namespace.remove()
# dict interface
def __getitem__(self, key):
return self.get(key)
def __contains__(self, key):
return self._get_value(key).has_current_value()
def has_key(self, key):
return key in self
def __delitem__(self, key):
self.remove_value(key)
def __setitem__(self, key, value):
self.put(key, value)
class CacheManager(object):
def __init__(self, **kwargs):
"""Initialize a CacheManager object with a set of options
Options should be parsed with the
:func:`~beaker.util.parse_cache_config_options` function to
ensure only valid options are used.
"""
self.kwargs = kwargs
self.regions = kwargs.pop('cache_regions', {})
# Add these regions to the module global
cache_regions.update(self.regions)
def get_cache(self, name, **kwargs):
kw = self.kwargs.copy()
kw.update(kwargs)
return Cache._get_cache(name, kw)
def get_cache_region(self, name, region):
if region not in self.regions:
raise BeakerException('Cache region not configured: %s' % region)
kw = self.regions[region]
return Cache._get_cache(name, kw)
def region(self, region, *args):
"""Decorate a function to cache itself using a cache region
The region decorator requires arguments if there are more than
2 of the same named function, in the same module. This is
because the namespace used for the functions cache is based on
the functions name and the module.
Example::
# Assuming a cache object is available like:
cache = CacheManager(dict_of_config_options)
def populate_things():
@cache.region('short_term', 'some_data')
def load(search_term, limit, offset):
return load_the_data(search_term, limit, offset)
return load('rabbits', 20, 0)
.. note::
The function being decorated must only be called with
positional arguments.
"""
return cache_region(region, *args)
def region_invalidate(self, namespace, region, *args):
"""Invalidate a cache region namespace or decorated function
This function only invalidates cache spaces created with the
cache_region decorator.
:param namespace: Either the namespace of the result to invalidate, or the
name of the cached function
:param region: The region the function was cached to. If the function was
cached to a single region then this argument can be None
:param args: Arguments that were used to differentiate the cached
function as well as the arguments passed to the decorated
function
Example::
# Assuming a cache object is available like:
cache = CacheManager(dict_of_config_options)
def populate_things(invalidate=False):
@cache.region('short_term', 'some_data')
def load(search_term, limit, offset):
return load_the_data(search_term, limit, offset)
# If the results should be invalidated first
if invalidate:
cache.region_invalidate(load, None, 'some_data',
'rabbits', 20, 0)
return load('rabbits', 20, 0)
"""
return region_invalidate(namespace, region, *args)
if callable(namespace):
if not region:
region = namespace._arg_region
namespace = namespace._arg_namespace
if not region:
raise BeakerException("Region or callable function "
"namespace is required")
else:
region = self.regions[region]
cache = self.get_cache(namespace, **region)
cache_key = " ".join(str(x) for x in args)
cache.remove_value(cache_key)
def cache(self, *args, **kwargs):
"""Decorate a function to cache itself with supplied parameters
:param args: Used to make the key unique for this function, as in region()
above.
:param kwargs: Parameters to be passed to get_cache(), will override defaults
Example::
# Assuming a cache object is available like:
cache = CacheManager(dict_of_config_options)
def populate_things():
@cache.cache('mycache', expire=15)
def load(search_term, limit, offset):
return load_the_data(search_term, limit, offset)
return load('rabbits', 20, 0)
.. note::
The function being decorated must only be called with
positional arguments.
"""
cache = [None]
key = " ".join(str(x) for x in args)
def decorate(func):
namespace = util.func_namespace(func)
def cached(*args):
if not cache[0]:
cache[0] = self.get_cache(namespace, **kwargs)
cache_key = key + " " + " ".join(str(x) for x in args)
def go():
return func(*args)
return cache[0].get_value(cache_key, createfunc=go)
cached._arg_namespace = namespace
return cached
return decorate
def invalidate(self, func, *args, **kwargs):
"""Invalidate a cache decorated function
This function only invalidates cache spaces created with the
cache decorator.
:param func: Decorated function to invalidate
:param args: Used to make the key unique for this function, as in region()
above.
:param kwargs: Parameters that were passed for use by get_cache(), note that
this is only required if a ``type`` was specified for the
function
Example::
# Assuming a cache object is available like:
cache = CacheManager(dict_of_config_options)
def populate_things(invalidate=False):
@cache.cache('mycache', type="file", expire=15)
def load(search_term, limit, offset):
return load_the_data(search_term, limit, offset)
# If the results should be invalidated first
if invalidate:
cache.invalidate(load, 'mycache', 'rabbits', 20, 0, type="file")
return load('rabbits', 20, 0)
"""
namespace = func._arg_namespace
cache = self.get_cache(namespace, **kwargs)
cache_key = " ".join(str(x) for x in args)
cache.remove_value(cache_key)