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"""Caching decorator, took as is from pylons"""
import tg, inspect, time
from tg.support.converters import asbool
from tg.support import NoDefault, EmptyContext
from tg._compat import im_func, im_class
from functools import wraps
class cached_property(object):
"""
Works like python @property but the decorated function only gets
executed once, successive accesses to the property will just
return the value previously stored into the object.
The ``@cached_property`` decorator can be executed within a
provided context, for example to make the cached property
thread safe a Lock can be provided::
from threading import Lock
from tg.caching import cached_property
class MyClass(object):
@cached_property
def my_property(self):
return 'Value!'
my_property.context = Lock()
"""
def __init__(self, func):
self.__name__ = func.__name__
self.__module__ = func.__module__
self.__doc__ = func.__doc__
self.func = func
self.context = EmptyContext()
def _get_value(self, obj):
value = obj.__dict__.get(self.__name__, NoDefault)
if value is NoDefault:
value = self.func(obj)
obj.__dict__[self.__name__] = value
return value
def __get__(self, obj, type=None):
if obj is None:
return self
with self.context:
return self._get_value(obj)
def _cached_call(func, args, kwargs, namespace, cache_key,
expire="never", type=None, starttime=None,
cache_headers=('content-type', 'content-length'),
cache_response=True, cache_extra_args=None):
"""
Optional arguments:
``key_func``
Function used to genereate the cache key, the function name
and class will be used as the base for the cache key. If None
the ``func`` itself will be used. It's usually handy when
creating caches for decorated functions, for which we want the
cache key to be generated on the decorated function and not on
the decorator.
``key_dict``
Arguments used to generate the cache key, only the arguments
listed into this dictionary will be used to generate the
cache key together with the key_func.
``expire``
Time in seconds before cache expires, or the string "never".
Defaults to "never"
``type``
Type of cache to use: dbm, memory, file, memcached, or None for
Beaker's default
``cache_headers``
A tuple of header names indicating response headers that
will also be cached.
``invalidate_on_startup``
If True, the cache will be invalidated each time the application
starts or is restarted.
``cache_response``
Determines whether the response at the time beaker_cache is used
should be cached or not, defaults to True.
.. note::
When cache_response is set to False, the cache_headers
argument is ignored as none of the response is cached.
If cache.enabled is set to False in the .ini file, then cache is
disabled globally.
"""
tg_locals = tg.request.environ['tg.locals']
enabled = asbool(tg_locals.config.get("cache.enabled", True))
if not enabled:
return func(*args, **kwargs)
cache_extra_args = cache_extra_args or {}
if type:
cache_extra_args['type'] = type
cache_obj = getattr(tg_locals, 'cache', None)
if not cache_obj: # pragma: no cover
raise Exception('TurboGears Cache object not found, ensure cache.enabled=True')
my_cache = cache_obj.get_cache(namespace, **cache_extra_args)
if expire == "never":
cache_expire = None
else:
cache_expire = expire
def create_func():
result = func(*args, **kwargs)
glob_response = tg_locals.response
headers = glob_response.headerlist
status = glob_response.status
full_response = dict(headers=headers, status=status,
cookies=None, content=result)
return full_response
response = my_cache.get_value(cache_key,
createfunc=create_func,
expiretime=cache_expire,
starttime=starttime)
if cache_response:
glob_response = tg_locals.response
glob_response.headerlist = [header for header in response['headers']
if header[0].lower() in cache_headers]
glob_response.status = response['status']
return response['content']
def beaker_cache(key="cache_default", expire="never", type=None,
query_args=False,
cache_headers=('content-type', 'content-length'),
invalidate_on_startup=False,
cache_response=True, **b_kwargs):
"""Cache decorator utilizing Beaker. Caches a
function that returns a pickle-able object as a result.
Optional arguments:
``key``
None - No variable key, uses function name as key
"cache_default" - Uses all function arguments as the key
string - Use kwargs[key] as key
list - Use [kwargs[k] for k in list] as key
``expire``
Time in seconds before cache expires, or the string "never".
Defaults to "never"
``type``
Type of cache to use: dbm, memory, file, memcached, or None for
Beaker's default
``query_args``
Uses the query arguments as the key, defaults to False
``cache_headers``
A tuple of header names indicating response headers that
will also be cached.
``invalidate_on_startup``
If True, the cache will be invalidated each time the application
starts or is restarted.
``cache_response``
Determines whether the response at the time beaker_cache is used
should be cached or not, defaults to True.
.. note::
When cache_response is set to False, the cache_headers
argument is ignored as none of the response is cached.
If cache.enabled is set to False in the .ini file, then cache is
disabled globally.
"""
if invalidate_on_startup:
starttime = time.time()
else:
starttime = None
cache_headers = set(cache_headers)
def beaker_cache_decorate(func):
@wraps(func)
def beaker_cached_call(*args, **kwargs):
if key:
key_dict = kwargs.copy()
key_dict.update(_make_dict_from_args(func, args, kwargs))
if query_args:
key_dict.update(tg.request.GET.mixed())
if key != 'cache_default':
if isinstance(key, list):
key_dict = dict((k, key_dict[k]) for k in key)
else:
key_dict = {key: key_dict[key]}
else:
key_dict = None
self = None
if args:
self = args[0]
namespace, cache_key = create_cache_key(func, key_dict, self)
return _cached_call(func, args, kwargs, namespace, cache_key,
expire, type, starttime,
cache_headers, cache_response,
b_kwargs)
return beaker_cached_call
return beaker_cache_decorate
def create_cache_key(func, key_dict=None, self=None):
"""Get a cache namespace and key used by the beaker_cache decorator.
Example::
from tg import cache
from tg.caching import create_cache_key
namespace, key = create_cache_key(MyController.some_method)
cache.get_cache(namespace).remove(key)
"""
kls = None
imfunc = im_func(func)
if imfunc:
kls = im_class(func)
func = imfunc
cache_key = func.__name__
else:
cache_key = func.__name__
if key_dict:
cache_key += " " + " ".join("%s=%s" % (k, v)
for k, v in key_dict.items())
if not kls and self:
kls = getattr(self, '__class__', None)
if kls:
return '%s.%s' % (kls.__module__, kls.__name__), cache_key
else:
return func.__module__, cache_key
def _make_dict_from_args(func, args, kwargs):
"""Inspects function for name of args"""
args_keys = {}
for i, arg in enumerate(inspect.getargspec(func)[0]):
if arg != "self":
try:
args_keys[arg] = args[i]
except IndexError:
args_keys[arg] = kwargs[arg]
return args_keys
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