moviewyrm/bookwyrm/activitystreams.py

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""" access the activity streams stored in redis """
from abc import ABC
from django.dispatch import receiver
from django.db.models import signals, Q
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import redis
from bookwyrm import models, settings
from bookwyrm.views.helpers import privacy_filter
r = redis.Redis(
host=settings.REDIS_ACTIVITY_HOST, port=settings.REDIS_ACTIVITY_PORT, db=0
)
class ActivityStream(ABC):
""" a category of activity stream (like home, local, federated) """
def stream_id(self, user):
""" the redis key for this user's instance of this stream """
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return "{}-{}".format(user.id, self.key)
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def unread_id(self, user):
""" the redis key for this user's unread count for this stream """
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return "{}-unread".format(self.stream_id(user))
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def add_status(self, status):
""" add a status to users' feeds """
# we want to do this as a bulk operation, hence "pipeline"
pipeline = r.pipeline()
for user in self.stream_users(status):
# add the status to the feed
pipeline.lpush(self.stream_id(user), status.id)
pipeline.ltrim(self.stream_id(user), 0, settings.MAX_STREAM_LENGTH)
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# add to the unread status count
pipeline.incr(self.unread_id(user))
# and go!
pipeline.execute()
def remove_status(self, status):
""" remove a status from all feeds """
pipeline = r.pipeline()
for user in self.stream_users(status):
pipeline.lrem(self.stream_id(user), -1, status.id)
pipeline.execute()
def add_user_statuses(self, viewer, user):
""" add a user's statuses to another user's feed """
pipeline = r.pipeline()
for status in user.status_set.all()[: settings.MAX_STREAM_LENGTH]:
pipeline.lpush(self.stream_id(viewer), status.id)
pipeline.execute()
def remove_user_statuses(self, viewer, user):
""" remove a user's status from another user's feed """
pipeline = r.pipeline()
for status in user.status_set.all()[: settings.MAX_STREAM_LENGTH]:
pipeline.lrem(self.stream_id(viewer), -1, status.id)
pipeline.execute()
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def get_activity_stream(self, user):
""" load the ids for statuses to be displayed """
# clear unreads for this feed
r.set(self.unread_id(user), 0)
statuses = r.lrange(self.stream_id(user), 0, -1)
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return (
models.Status.objects.select_subclasses()
.filter(id__in=statuses)
.order_by("-published_date")
)
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def get_unread_count(self, user):
""" get the unread status count for this user's feed """
return int(r.get(self.unread_id(user)))
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def populate_stream(self, user):
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""" go from zero to a timeline """
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pipeline = r.pipeline()
statuses = self.stream_statuses(user)
stream_id = self.stream_id(user)
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for status in statuses.all()[: settings.MAX_STREAM_LENGTH]:
pipeline.lpush(stream_id, status.id)
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pipeline.execute()
def stream_users(self, status): # pylint: disable=no-self-use
""" given a status, what users should see it """
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# direct messages don't appeard in feeds, direct comments/reviews/etc do
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if status.privacy == "direct" and status.status_type == "Note":
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return []
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# everybody who could plausibly see this status
audience = models.User.objects.filter(
is_active=True,
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local=True, # we only create feeds for users of this instance
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).exclude(
Q(id__in=status.user.blocks.all()) | Q(blocks=status.user) # not blocked
)
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# only visible to the poster and mentioned users
if status.privacy == "direct":
audience = audience.filter(
Q(id=status.user.id) # if the user is the post's author
| Q(id__in=status.mention_users.all()) # if the user is mentioned
)
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# only visible to the poster's followers and tagged users
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elif status.privacy == "followers":
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audience = audience.filter(
Q(id=status.user.id) # if the user is the post's author
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| Q(following=status.user) # if the user is following the author
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)
return audience.distinct()
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def stream_statuses(self, user): # pylint: disable=no-self-use
""" given a user, what statuses should they see on this stream """
return privacy_filter(
user,
models.Status.objects.select_subclasses(),
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privacy_levels=["public", "unlisted", "followers"],
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)
class HomeStream(ActivityStream):
""" users you follow """
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key = "home"
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def stream_users(self, status):
audience = super().stream_users(status)
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if not audience:
return []
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return audience.filter(
Q(id=status.user.id) # if the user is the post's author
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| Q(following=status.user) # if the user is following the author
).distinct()
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def stream_statuses(self, user):
return privacy_filter(
user,
models.Status.objects.select_subclasses(),
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privacy_levels=["public", "unlisted", "followers"],
following_only=True,
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)
class LocalStream(ActivityStream):
""" users you follow """
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key = "local"
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def stream_users(self, status):
# this stream wants no part in non-public statuses
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if status.privacy != "public" or not status.user.local:
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return []
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return super().stream_users(status)
def stream_statuses(self, user):
# all public statuses by a local user
return privacy_filter(
user,
models.Status.objects.select_subclasses().filter(user__local=True),
privacy_levels=["public"],
)
class FederatedStream(ActivityStream):
""" users you follow """
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key = "federated"
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def stream_users(self, status):
# this stream wants no part in non-public statuses
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if status.privacy != "public":
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return []
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return super().stream_users(status)
def stream_statuses(self, user):
return privacy_filter(
user,
models.Status.objects.select_subclasses(),
privacy_levels=["public"],
)
streams = {
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"home": HomeStream(),
"local": LocalStream(),
"federated": FederatedStream(),
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}
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@receiver(signals.post_save)
# pylint: disable=unused-argument
def add_status_on_create(sender, instance, created, *args, **kwargs):
""" add newly created statuses to activity feeds """
# we're only interested in new statuses
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if not issubclass(sender, models.Status):
return
if instance.deleted:
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for stream in streams.values():
stream.remove_status(instance)
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return
if not created:
return
# iterates through Home, Local, Federated
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for stream in streams.values():
stream.add_status(instance)
@receiver(signals.post_delete, sender=models.Boost)
# pylint: disable=unused-argument
def remove_boost_on_delete(sender, instance, *args, **kwargs):
""" boosts are deleted """
# we're only interested in new statuses
for stream in streams.values():
stream.remove_status(instance)
@receiver(signals.post_save, sender=models.UserFollows)
# pylint: disable=unused-argument
def add_statuses_on_follow(sender, instance, created, *args, **kwargs):
""" add a newly followed user's statuses to feeds """
if not created or not instance.user_subject.local:
return
HomeStream().add_user_statuses(instance.user_subject, instance.user_object)
@receiver(signals.post_delete, sender=models.UserFollows)
# pylint: disable=unused-argument
def remove_statuses_on_unfollow(sender, instance, *args, **kwargs):
""" remove statuses from a feed on unfollow """
if not instance.user_subject.local:
return
HomeStream().remove_user_statuses(instance.user_subject, instance.user_object)
@receiver(signals.post_save, sender=models.UserBlocks)
# pylint: disable=unused-argument
def remove_statuses_on_block(sender, instance, *args, **kwargs):
""" remove statuses from all feeds on block """
# blocks apply ot all feeds
if instance.user_subject.local:
for stream in streams.values():
stream.remove_user_statuses(instance.user_subject, instance.user_object)
# and in both directions
if instance.user_object.local:
for stream in streams.values():
stream.remove_user_statuses(instance.user_object, instance.user_subject)
@receiver(signals.post_delete, sender=models.UserBlocks)
# pylint: disable=unused-argument
def add_statuses_on_unblock(sender, instance, *args, **kwargs):
""" remove statuses from all feeds on block """
public_streams = [LocalStream(), FederatedStream()]
# add statuses back to streams with statuses from anyone
if instance.user_subject.local:
for stream in public_streams:
stream.add_user_statuses(instance.user_subject, instance.user_object)
# add statuses back to streams with statuses from anyone
if instance.user_object.local:
for stream in public_streams:
stream.add_user_statuses(instance.user_object, instance.user_subject)
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@receiver(signals.post_save, sender=models.User)
# pylint: disable=unused-argument
def populate_feed_on_account_create(sender, instance, created, *args, **kwargs):
""" build a user's feeds when they join """
if not created or not instance.local:
return
for stream in streams.values():
stream.populate_stream(instance)