# Copyright (C) 2010-2023 RhodeCode GmbH # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU Affero General Public License, version 3 # (only), as published by the Free Software Foundation. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU Affero General Public License # along with this program. If not, see . # # This program is dual-licensed. If you wish to learn more about the # RhodeCode Enterprise Edition, including its added features, Support services, # and proprietary license terms, please see https://rhodecode.com/licenses/ """caching_query.py Represent functions and classes which allow the usage of Dogpile caching with SQLAlchemy. Introduces a query option called FromCache. .. versionchanged:: 1.4 the caching approach has been altered to work based on a session event. The three new concepts introduced here are: * ORMCache - an extension for an ORM :class:`.Session` retrieves results in/from dogpile.cache. * FromCache - a query option that establishes caching parameters on a Query * RelationshipCache - a variant of FromCache which is specific to a query invoked during a lazy load. The rest of what's here are standard SQLAlchemy and dogpile.cache constructs. """ from dogpile.cache.api import NO_VALUE from sqlalchemy import event from sqlalchemy.orm import loading from sqlalchemy.orm.interfaces import UserDefinedOption DEFAULT_REGION = "sql_cache_short" class ORMCache: """An add-on for an ORM :class:`.Session` optionally loads full results from a dogpile cache region. cache = ORMCache(regions={}) cache.listen_on_session(Session) """ def __init__(self, regions): self.cache_regions = regions or self._get_region() self._statement_cache = {} @classmethod def _get_region(cls): from rhodecode.lib.rc_cache import region_meta return region_meta.dogpile_cache_regions def listen_on_session(self, session_factory): event.listen(session_factory, "do_orm_execute", self._do_orm_execute) def _do_orm_execute(self, orm_context): for opt in orm_context.user_defined_options: if isinstance(opt, RelationshipCache): opt = opt._process_orm_context(orm_context) if opt is None: continue if isinstance(opt, FromCache): dogpile_region = self.cache_regions[opt.region] if dogpile_region.expiration_time <= 0: # don't cache 0 time expiration cache continue if opt.cache_key: our_cache_key = f'SQL_CACHE_{opt.cache_key}' else: our_cache_key = opt._generate_cache_key( orm_context.statement, orm_context.parameters, self ) if opt.ignore_expiration: cached_value = dogpile_region.get( our_cache_key, expiration_time=opt.expiration_time, ignore_expiration=opt.ignore_expiration, ) else: def createfunc(): return orm_context.invoke_statement().freeze() cached_value = dogpile_region.get_or_create( our_cache_key, createfunc, expiration_time=opt.expiration_time, ) if cached_value is NO_VALUE: # keyerror? this is bigger than a keyerror... raise KeyError() orm_result = loading.merge_frozen_result( orm_context.session, orm_context.statement, cached_value, load=False, ) return orm_result() else: return None def invalidate(self, statement, parameters, opt): """Invalidate the cache value represented by a statement.""" statement = statement.__clause_element__() dogpile_region = self.cache_regions[opt.region] cache_key = opt._generate_cache_key(statement, parameters, self) dogpile_region.delete(cache_key) class FromCache(UserDefinedOption): """Specifies that a Query should load results from a cache.""" propagate_to_loaders = False def __init__( self, region=DEFAULT_REGION, cache_key=None, expiration_time=None, ignore_expiration=False, ): """Construct a new FromCache. :param region: the cache region. Should be a region configured in the dictionary of dogpile regions. :param cache_key: optional. A string cache key that will serve as the key to the query. Use this if your query has a huge amount of parameters (such as when using in_()) which correspond more simply to some other identifier. """ self.region = region self.cache_key = cache_key self.expiration_time = expiration_time self.ignore_expiration = ignore_expiration # this is not needed as of SQLAlchemy 1.4.28; # UserDefinedOption classes no longer participate in the SQL # compilation cache key def _gen_cache_key(self, anon_map, bindparams): return None def _generate_cache_key(self, statement, parameters, orm_cache): """generate a cache key with which to key the results of a statement. This leverages the use of the SQL compilation cache key which is repurposed as a SQL results key. """ statement_cache_key = statement._generate_cache_key() key = statement_cache_key.to_offline_string( orm_cache._statement_cache, statement, parameters ) + repr(self.cache_key) # print("here's our key...%s" % key) return key class RelationshipCache(FromCache): """Specifies that a Query as called within a "lazy load" should load results from a cache.""" propagate_to_loaders = True def __init__( self, attribute, region=DEFAULT_REGION, cache_key=None, expiration_time=None, ignore_expiration=False, ): """Construct a new RelationshipCache. :param attribute: A Class.attribute which indicates a particular class relationship() whose lazy loader should be pulled from the cache. :param region: name of the cache region. :param cache_key: optional. A string cache key that will serve as the key to the query, bypassing the usual means of forming a key from the Query itself. """ self.region = region self.cache_key = cache_key self.expiration_time = expiration_time self.ignore_expiration = ignore_expiration self._relationship_options = { (attribute.property.parent.class_, attribute.property.key): self } def _process_orm_context(self, orm_context): current_path = orm_context.loader_strategy_path if current_path: mapper, prop = current_path[-2:] key = prop.key for cls in mapper.class_.__mro__: if (cls, key) in self._relationship_options: relationship_option = self._relationship_options[ (cls, key) ] return relationship_option def and_(self, option): """Chain another RelationshipCache option to this one. While many RelationshipCache objects can be specified on a single Query separately, chaining them together allows for a more efficient lookup during load. """ self._relationship_options.update(option._relationship_options) return self