moviewyrm/bookwyrm/redis_store.py

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""" access the activity stores stored in redis """
from abc import ABC, abstractmethod
import redis
from bookwyrm import settings
r = redis.Redis(
host=settings.REDIS_ACTIVITY_HOST, port=settings.REDIS_ACTIVITY_PORT, db=0
)
class RedisStore(ABC):
""" sets of ranked, related objects, like statuses for a user's feed """
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max_length = settings.MAX_STREAM_LENGTH
def get_value(self, obj):
""" the object and rank """
return {obj.id: self.get_rank(obj)}
def add_object_to_related_stores(self, obj, execute=True):
""" add an object to all suitable stores """
value = self.get_value(obj)
# we want to do this as a bulk operation, hence "pipeline"
pipeline = r.pipeline()
for store in self.get_stores_for_object(obj):
# add the status to the feed
pipeline.zadd(store, value)
# trim the store
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pipeline.zremrangebyrank(store, 0, -1 * self.max_length)
if not execute:
return pipeline
# and go!
return pipeline.execute()
def remove_object_from_related_stores(self, obj):
""" remove an object from all stores """
pipeline = r.pipeline()
for store in self.get_stores_for_object(obj):
pipeline.zrem(store, -1, obj.id)
pipeline.execute()
def bulk_add_objects_to_store(self, objs, store):
""" add a list of objects to a given store """
pipeline = r.pipeline()
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for obj in objs[: self.max_length]:
pipeline.zadd(store, self.get_value(obj))
if objs:
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pipeline.zremrangebyrank(store, 0, -1 * self.max_length)
pipeline.execute()
def bulk_remove_objects_from_store(self, objs, store):
""" remoev a list of objects from a given store """
pipeline = r.pipeline()
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for obj in objs[: self.max_length]:
pipeline.zrem(store, -1, obj.id)
pipeline.execute()
def get_store(self, store): # pylint: disable=no-self-use
""" load the values in a store """
return r.zrevrange(store, 0, -1)
def populate_store(self, store):
""" go from zero to a store """
pipeline = r.pipeline()
queryset = self.get_objects_for_store(store)
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for obj in queryset[: self.max_length]:
pipeline.zadd(store, self.get_value(obj))
# only trim the store if objects were added
if queryset.exists():
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pipeline.zremrangebyrank(store, 0, -1 * self.max_length)
pipeline.execute()
@abstractmethod
def get_objects_for_store(self, store):
""" a queryset of what should go in a store, used for populating it """
@abstractmethod
def get_stores_for_object(self, obj):
""" the stores that an object belongs in """
@abstractmethod
def get_rank(self, obj):
""" how to rank an object """