# mako/cache.py # Copyright 2006-2019 the Mako authors and contributors <see AUTHORS file> # # This module is part of Mako and is released under # the MIT License: http://www.opensource.org/licenses/mit-license.php from mako import compat from mako import util _cache_plugins = util.PluginLoader("mako.cache") register_plugin = _cache_plugins.register register_plugin("beaker", "mako.ext.beaker_cache", "BeakerCacheImpl") class Cache(object): """Represents a data content cache made available to the module space of a specific :class:`.Template` object. .. versionadded:: 0.6 :class:`.Cache` by itself is mostly a container for a :class:`.CacheImpl` object, which implements a fixed API to provide caching services; specific subclasses exist to implement different caching strategies. Mako includes a backend that works with the Beaker caching system. Beaker itself then supports a number of backends (i.e. file, memory, memcached, etc.) The construction of a :class:`.Cache` is part of the mechanics of a :class:`.Template`, and programmatic access to this cache is typically via the :attr:`.Template.cache` attribute. """ impl = None """Provide the :class:`.CacheImpl` in use by this :class:`.Cache`. This accessor allows a :class:`.CacheImpl` with additional methods beyond that of :class:`.Cache` to be used programmatically. """ id = None """Return the 'id' that identifies this cache. This is a value that should be globally unique to the :class:`.Template` associated with this cache, and can be used by a caching system to name a local container for data specific to this template. """ starttime = None """Epochal time value for when the owning :class:`.Template` was first compiled. A cache implementation may wish to invalidate data earlier than this timestamp; this has the effect of the cache for a specific :class:`.Template` starting clean any time the :class:`.Template` is recompiled, such as when the original template file changed on the filesystem. """ def __init__(self, template, *args): # check for a stale template calling the # constructor if isinstance(template, compat.string_types) and args: return self.template = template self.id = template.module.__name__ self.starttime = template.module._modified_time self._def_regions = {} self.impl = self._load_impl(self.template.cache_impl) def _load_impl(self, name): return _cache_plugins.load(name)(self) def get_or_create(self, key, creation_function, **kw): """Retrieve a value from the cache, using the given creation function to generate a new value.""" return self._ctx_get_or_create(key, creation_function, None, **kw) def _ctx_get_or_create(self, key, creation_function, context, **kw): """Retrieve a value from the cache, using the given creation function to generate a new value.""" if not self.template.cache_enabled: return creation_function() return self.impl.get_or_create( key, creation_function, **self._get_cache_kw(kw, context) ) def set(self, key, value, **kw): r"""Place a value in the cache. :param key: the value's key. :param value: the value. :param \**kw: cache configuration arguments. """ self.impl.set(key, value, **self._get_cache_kw(kw, None)) put = set """A synonym for :meth:`.Cache.set`. This is here for backwards compatibility. """ def get(self, key, **kw): r"""Retrieve a value from the cache. :param key: the value's key. :param \**kw: cache configuration arguments. The backend is configured using these arguments upon first request. Subsequent requests that use the same series of configuration values will use that same backend. """ return self.impl.get(key, **self._get_cache_kw(kw, None)) def invalidate(self, key, **kw): r"""Invalidate a value in the cache. :param key: the value's key. :param \**kw: cache configuration arguments. The backend is configured using these arguments upon first request. Subsequent requests that use the same series of configuration values will use that same backend. """ self.impl.invalidate(key, **self._get_cache_kw(kw, None)) def invalidate_body(self): """Invalidate the cached content of the "body" method for this template. """ self.invalidate("render_body", __M_defname="render_body") def invalidate_def(self, name): """Invalidate the cached content of a particular ``<%def>`` within this template. """ self.invalidate("render_%s" % name, __M_defname="render_%s" % name) def invalidate_closure(self, name): """Invalidate a nested ``<%def>`` within this template. Caching of nested defs is a blunt tool as there is no management of scope -- nested defs that use cache tags need to have names unique of all other nested defs in the template, else their content will be overwritten by each other. """ self.invalidate(name, __M_defname=name) def _get_cache_kw(self, kw, context): defname = kw.pop("__M_defname", None) if not defname: tmpl_kw = self.template.cache_args.copy() tmpl_kw.update(kw) elif defname in self._def_regions: tmpl_kw = self._def_regions[defname] else: tmpl_kw = self.template.cache_args.copy() tmpl_kw.update(kw) self._def_regions[defname] = tmpl_kw if context and self.impl.pass_context: tmpl_kw = tmpl_kw.copy() tmpl_kw.setdefault("context", context) return tmpl_kw class CacheImpl(object): """Provide a cache implementation for use by :class:`.Cache`.""" def __init__(self, cache): self.cache = cache pass_context = False """If ``True``, the :class:`.Context` will be passed to :meth:`get_or_create <.CacheImpl.get_or_create>` as the name ``'context'``. """ def get_or_create(self, key, creation_function, **kw): r"""Retrieve a value from the cache, using the given creation function to generate a new value. This function *must* return a value, either from the cache, or via the given creation function. If the creation function is called, the newly created value should be populated into the cache under the given key before being returned. :param key: the value's key. :param creation_function: function that when called generates a new value. :param \**kw: cache configuration arguments. """ raise NotImplementedError() def set(self, key, value, **kw): r"""Place a value in the cache. :param key: the value's key. :param value: the value. :param \**kw: cache configuration arguments. """ raise NotImplementedError() def get(self, key, **kw): r"""Retrieve a value from the cache. :param key: the value's key. :param \**kw: cache configuration arguments. """ raise NotImplementedError() def invalidate(self, key, **kw): r"""Invalidate a value in the cache. :param key: the value's key. :param \**kw: cache configuration arguments. """ raise NotImplementedError()