87 lines
3.0 KiB
Python
87 lines
3.0 KiB
Python
import logging
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from typing import Dict, Iterable, Tuple
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from sqlalchemy.orm import Session, make_transient
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from platypush.entities import Entity
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from platypush.entities._engine.repo.cache import EntitiesCache
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from platypush.entities._engine.repo.db import EntitiesDb
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from platypush.entities._engine.repo.merger import EntitiesMerger
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logger = logging.getLogger('entities')
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class EntitiesRepository:
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"""
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This object is used to get and save entities, and it wraps database and
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cache objects.
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"""
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def __init__(self):
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self._cache = EntitiesCache()
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self._db = EntitiesDb()
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self._merger = EntitiesMerger(self)
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self._init_entities_cache()
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def _init_entities_cache(self):
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"""
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Initializes the repository with the existing entities.
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"""
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logger.info('Initializing entities cache')
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with self._db.get_session() as session:
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entities = session.query(Entity).all()
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for entity in entities:
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make_transient(entity)
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self._cache.update(*entities, overwrite=True)
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logger.info('Entities cache initialized')
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def get(
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self, session: Session, entities: Iterable[Entity]
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) -> Dict[Tuple[str, str], Entity]:
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"""
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Given a set of entity objects, it returns those that already exist
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(or have the same ``entity_key``). It looks up both the cache and the
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database.
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"""
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entities_map: Dict[Tuple[str, str], Entity] = {
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e.entity_key: e for e in entities
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}
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# Fetch the entities that exist in the cache
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existing_entities = {}
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# TODO UNCOMMENT THIS CODE TO ACTUALLY USE THE CACHE!
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# existing_entities = {
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# key: self._entities_cache.by_external_id_and_plugin[key]
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# for key in entities_map.keys()
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# if key in self._entities_cache.by_external_id_and_plugin
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# }
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# Retrieve from the database the entities that miss from the cache
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cache_miss_entities = {
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key: e for key, e in entities_map.items() if key not in existing_entities
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}
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cache_miss_existing_entities = self._db.fetch(
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session, cache_miss_entities.values()
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)
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# Update the cache
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self._cache.update(*cache_miss_existing_entities.values())
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# Return the union of the cached + retrieved entities
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existing_entities.update(cache_miss_existing_entities)
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return existing_entities
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def save(self, *entities: Entity) -> Iterable[Entity]:
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"""
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Perform an upsert of entities after merging duplicates and rebuilding
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the taxonomies. It updates both the database and the cache.
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"""
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with self._db.get_session(locked=True, autoflush=False) as session:
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merged_entities = self._merger.merge(session, entities)
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merged_entities = self._db.upsert(session, merged_entities)
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self._cache.update(*merged_entities, overwrite=True)
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return merged_entities
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