"""This package contains the "front end" classes and functions for Beaker caching. Included are the :class:`.Cache` and :class:`.CacheManager` classes, as well as the function decorators :func:`.region_decorate`, :func:`.region_invalidate`. """ import warnings from itertools import chain from beaker._compat import u_, unicode_text, func_signature, bindfuncargs import beaker.container as container import beaker.util as util from beaker.crypto.util import sha1 from beaker.exceptions import BeakerException, InvalidCacheBackendError from beaker.synchronization import _threading import beaker.ext.memcached as memcached import beaker.ext.database as database import beaker.ext.sqla as sqla import beaker.ext.google as google import beaker.ext.mongodb as mongodb import beaker.ext.redisnm as redisnm from functools import wraps # Initialize the cache region dict cache_regions = {} """Dictionary of 'region' arguments. A "region" is a string name that refers to a series of cache configuration arguments. An application may have multiple "regions" - one which stores things in a memory cache, one which writes data to files, etc. The dictionary stores string key names mapped to dictionaries of configuration arguments. Example:: from beaker.cache import cache_regions cache_regions.update({ 'short_term':{ 'expire':60, 'type':'memory' }, 'long_term':{ 'expire':1800, 'type':'dbm', 'data_dir':'/tmp', } }) """ cache_managers = {} class _backends(object): initialized = False def __init__(self, clsmap): self._clsmap = clsmap self._mutex = _threading.Lock() def __getitem__(self, key): try: return self._clsmap[key] except KeyError as e: if not self.initialized: self._mutex.acquire() try: if not self.initialized: self._init() self.initialized = True return self._clsmap[key] finally: self._mutex.release() raise e def _init(self): try: import pkg_resources # Load up the additional entry point defined backends for entry_point in pkg_resources.iter_entry_points('beaker.backends'): try: namespace_manager = entry_point.load() name = entry_point.name if name in self._clsmap: raise BeakerException("NamespaceManager name conflict,'%s' " "already loaded" % name) self._clsmap[name] = namespace_manager 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 try: from StringIO import StringIO # Python2 except ImportError: from io import StringIO # Python3 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 # Initialize the basic available backends clsmap = _backends({ '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, 'ext:mongodb': mongodb.MongoNamespaceManager, 'ext:redis': redisnm.RedisNamespaceManager }) def cache_region(region, *args): """Decorate a function such that its return result is cached, using a "region" to indicate the cache arguments. Example:: from beaker.cache import cache_regions, cache_region # configure regions cache_regions.update({ 'short_term':{ 'expire':60, 'type':'memory' } }) @cache_region('short_term', 'load_things') def load(search_term, limit, offset): '''Load from a database given a search term, limit, offset.''' return database.query(search_term)[offset:offset + limit] The decorator can also be used with object methods. The ``self`` argument is not part of the cache key. This is based on the actual string name ``self`` being in the first argument position (new in 1.6):: class MyThing(object): @cache_region('short_term', 'load_things') def load(self, search_term, limit, offset): '''Load from a database given a search term, limit, offset.''' return database.query(search_term)[offset:offset + limit] Classmethods work as well - use ``cls`` as the name of the class argument, and place the decorator around the function underneath ``@classmethod`` (new in 1.6):: class MyThing(object): @classmethod @cache_region('short_term', 'load_things') def load(cls, search_term, limit, offset): '''Load from a database given a search term, limit, offset.''' return database.query(search_term)[offset:offset + limit] :param region: String name of the region corresponding to the desired caching arguments, established in :attr:`.cache_regions`. :param \*args: Optional ``str()``-compatible arguments which will uniquely identify the key used by this decorated function, in addition to the positional arguments passed to the function itself at call time. This is recommended as it is needed to distinguish between any two functions or methods that have the same name (regardless of parent class or not). .. note:: The function being decorated must only be called with positional arguments, and the arguments must support being stringified with ``str()``. The concatenation of the ``str()`` version of each argument, combined with that of the ``*args`` sent to the decorator, forms the unique cache key. .. note:: When a method on a class is decorated, the ``self`` or ``cls`` argument in the first position is not included in the "key" used for caching. New in 1.6. """ return _cache_decorate(args, None, None, region) def region_invalidate(namespace, region, *args): """Invalidate a cache region corresponding to a function decorated with :func:`.cache_region`. :param namespace: The namespace of the cache to invalidate. This is typically a reference to the original function (as returned by the :func:`.cache_region` decorator), where the :func:`.cache_region` decorator applies a "memo" to the function in order to locate the string name of the namespace. :param region: String name of the region used with the decorator. This can be ``None`` in the usual case that the decorated function itself is passed, not the string name of the namespace. :param args: Stringifyable arguments that are used to locate the correct key. This consists of the ``*args`` sent to the :func:`.cache_region` decorator itself, plus the ``*args`` sent to the function itself at runtime. Example:: from beaker.cache import cache_regions, cache_region, region_invalidate # configure regions cache_regions.update({ 'short_term':{ 'expire':60, 'type':'memory' } }) @cache_region('short_term', 'load_data') def load(search_term, limit, offset): '''Load from a database given a search term, limit, offset.''' return database.query(search_term)[offset:offset + limit] def invalidate_search(search_term, limit, offset): '''Invalidate the cached storage for a given search term, limit, offset.''' region_invalidate(load, 'short_term', 'load_data', search_term, limit, offset) Note that when a method on a class is decorated, the first argument ``cls`` or ``self`` is not included in the cache key. This means you don't send it to :func:`.region_invalidate`:: class MyThing(object): @cache_region('short_term', 'some_data') def load(self, search_term, limit, offset): '''Load from a database given a search term, limit, offset.''' return database.query(search_term)[offset:offset + limit] def invalidate_search(self, search_term, limit, offset): '''Invalidate the cached storage for a given search term, limit, offset.''' region_invalidate(self.load, 'short_term', 'some_data', search_term, limit, offset) """ 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_decorator_invalidate(cache, region.get('key_length', util.DEFAULT_CACHE_KEY_LENGTH), args) 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) if expire is not None: expire = int(expire) self.namespace_name = namespace 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) mycontainer.clear_value() remove = remove_value def _get_value(self, key, **kw): if isinstance(key, unicode_text): 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 two 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 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) 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. """ return _cache_decorate(args, self, kwargs, None) 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) if hasattr(func, '_arg_region'): cachereg = cache_regions[func._arg_region] key_length = cachereg.get('key_length', util.DEFAULT_CACHE_KEY_LENGTH) else: key_length = kwargs.pop('key_length', util.DEFAULT_CACHE_KEY_LENGTH) _cache_decorator_invalidate(cache, key_length, args) def _cache_decorate(deco_args, manager, options, region): """Return a caching function decorator.""" cache = [None] def decorate(func): namespace = util.func_namespace(func) skip_self = util.has_self_arg(func) signature = func_signature(func) @wraps(func) def cached(*args, **kwargs): if not cache[0]: if region is not None: if region not in cache_regions: raise BeakerException( 'Cache region not configured: %s' % region) reg = cache_regions[region] if not reg.get('enabled', True): return func(*args, **kwargs) cache[0] = Cache._get_cache(namespace, reg) elif manager: cache[0] = manager.get_cache(namespace, **options) else: raise Exception("'manager + kwargs' or 'region' " "argument is required") cache_key_kwargs = [] if kwargs: # kwargs provided, merge them in positional args # to avoid having different cache keys. args, kwargs = bindfuncargs(signature, args, kwargs) cache_key_kwargs = [u_(':').join((u_(key), u_(value))) for key, value in kwargs.items()] cache_key_args = args if skip_self: cache_key_args = args[1:] cache_key = u_(" ").join(map(u_, chain(deco_args, cache_key_args, cache_key_kwargs))) if region: cachereg = cache_regions[region] key_length = cachereg.get('key_length', util.DEFAULT_CACHE_KEY_LENGTH) else: key_length = options.pop('key_length', util.DEFAULT_CACHE_KEY_LENGTH) # TODO: This is probably a bug as length is checked before converting to UTF8 # which will cause cache_key to grow in size. if len(cache_key) + len(namespace) > int(key_length): cache_key = sha1(cache_key.encode('utf-8')).hexdigest() def go(): return func(*args, **kwargs) # save org function name go.__name__ = '_cached_%s' % (func.__name__,) return cache[0].get_value(cache_key, createfunc=go) cached._arg_namespace = namespace if region is not None: cached._arg_region = region return cached return decorate def _cache_decorator_invalidate(cache, key_length, args): """Invalidate a cache key based on function arguments.""" cache_key = u_(" ").join(map(u_, args)) if len(cache_key) + len(cache.namespace_name) > key_length: cache_key = sha1(cache_key.encode('utf-8')).hexdigest() cache.remove_value(cache_key)