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# frozen_string_literal: true
require 'singleton'
class FeedManager
include Singleton
MAX_ITEMS = 400
# Must be <= MAX_ITEMS or the tracking sets will grow forever
REBLOG_FALLOFF = 40
def key(type, id, subtype = nil)
return "feed:#{type}:#{id}" unless subtype
"feed:#{type}:#{id}:#{subtype}"
end
def filter?(timeline_type, status, receiver_id)
if timeline_type == :home
filter_from_home?(status, receiver_id)
elsif timeline_type == :mentions
filter_from_mentions?(status, receiver_id)
else
false
end
end
def push(timeline_type, account, status)
return false unless add_to_feed(timeline_type, account, status)
trim(timeline_type, account.id)
PushUpdateWorker.perform_async(account.id, status.id) if push_update_required?(timeline_type, account.id)
true
end
def unpush(timeline_type, account, status)
return false unless remove_from_feed(timeline_type, account, status)
payload = Oj.dump(event: :delete, payload: status.id.to_s)
Redis.current.publish("timeline:#{account.id}", payload)
true
end
def trim(type, account_id)
timeline_key = key(type, account_id)
reblog_key = key(type, account_id, 'reblogs')
# Remove any items past the MAX_ITEMS'th entry in our feed
redis.zremrangebyrank(timeline_key, '0', (-(FeedManager::MAX_ITEMS + 1)).to_s)
# Get the score of the REBLOG_FALLOFF'th item in our feed, and stop
# tracking anything after it for deduplication purposes.
falloff_rank = FeedManager::REBLOG_FALLOFF - 1
falloff_range = redis.zrevrange(timeline_key, falloff_rank, falloff_rank, with_scores: true)
falloff_score = falloff_range&.first&.last&.to_i || 0
redis.zremrangebyscore(reblog_key, 0, falloff_score)
end
def push_update_required?(timeline_type, account_id)
timeline_type != :home || redis.get("subscribed:timeline:#{account_id}").present?
end
def merge_into_timeline(from_account, into_account)
timeline_key = key(:home, into_account.id)
query = from_account.statuses.limit(FeedManager::MAX_ITEMS / 4)
if redis.zcard(timeline_key) >= FeedManager::MAX_ITEMS / 4
oldest_home_score = redis.zrange(timeline_key, 0, 0, with_scores: true)&.first&.last&.to_i || 0
query = query.where('id > ?', oldest_home_score)
end
query.each do |status|
next if status.direct_visibility? || filter?(:home, status, into_account)
add_to_feed(:home, into_account, status)
end
trim(:home, into_account.id)
end
def unmerge_from_timeline(from_account, into_account)
timeline_key = key(:home, into_account.id)
oldest_home_score = redis.zrange(timeline_key, 0, 0, with_scores: true)&.first&.last&.to_i || 0
from_account.statuses.select('id').where('id > ?', oldest_home_score).reorder(nil).find_in_batches do |statuses|
statuses.each do |status|
unpush(:home, into_account, status)
end
end
end
def clear_from_timeline(account, target_account)
timeline_key = key(:home, account.id)
timeline_status_ids = redis.zrange(timeline_key, 0, -1)
target_statuses = Status.where(id: timeline_status_ids, account: target_account)
target_statuses.each do |status|
unpush(:home, account, status)
end
end
def populate_feed(account)
prepopulate_limit = FeedManager::MAX_ITEMS / 4
statuses = Status.as_home_timeline(account).order(account_id: :desc).limit(prepopulate_limit)
statuses.reverse_each do |status|
next if filter_from_home?(status, account)
add_to_feed(:home, account, status)
end
end
private
def redis
Redis.current
end
def filter_from_home?(status, receiver_id)
return true if status.reply? && (status.in_reply_to_id.nil? || status.in_reply_to_account_id.nil?)
check_for_mutes = [status.account_id]
check_for_mutes.concat([status.reblog.account_id]) if status.reblog?
return true if Mute.where(account_id: receiver_id, target_account_id: check_for_mutes).any?
check_for_blocks = status.mentions.pluck(:account_id)
check_for_blocks.concat([status.reblog.account_id]) if status.reblog?
return true if Block.where(account_id: receiver_id, target_account_id: check_for_blocks).any?
if status.reply? && !status.in_reply_to_account_id.nil? # Filter out if it's a reply
should_filter = !Follow.where(account_id: receiver_id, target_account_id: status.in_reply_to_account_id).exists? # and I'm not following the person it's a reply to
should_filter &&= receiver_id != status.in_reply_to_account_id # and it's not a reply to me
should_filter &&= status.account_id != status.in_reply_to_account_id # and it's not a self-reply
return should_filter
elsif status.reblog? # Filter out a reblog
should_filter = Block.where(account_id: status.reblog.account_id, target_account_id: receiver_id).exists? # or if the author of the reblogged status is blocking me
should_filter ||= AccountDomainBlock.where(account_id: receiver_id, domain: status.reblog.account.domain).exists? # or the author's domain is blocked
return should_filter
end
false
end
def filter_from_mentions?(status, receiver_id)
return true if receiver_id == status.account_id
check_for_blocks = [status.account_id]
check_for_blocks.concat(status.mentions.pluck(:account_id))
check_for_blocks.concat([status.in_reply_to_account]) if status.reply? && !status.in_reply_to_account_id.nil?
should_filter = Block.where(account_id: receiver_id, target_account_id: check_for_blocks).any? # Filter if it's from someone I blocked, in reply to someone I blocked, or mentioning someone I blocked
should_filter ||= (status.account.silenced? && !Follow.where(account_id: receiver_id, target_account_id: status.account_id).exists?) # of if the account is silenced and I'm not following them
should_filter
end
# Adds a status to an account's feed, returning true if a status was
# added, and false if it was not added to the feed. Note that this is
# an internal helper: callers must call trim or push updates if
# either action is appropriate.
def add_to_feed(timeline_type, account, status)
timeline_key = key(timeline_type, account.id)
reblog_key = key(timeline_type, account.id, 'reblogs')
if status.reblog?
# If the original status or a reblog of it is within
# REBLOG_FALLOFF statuses from the top, do not re-insert it into
# the feed
rank = redis.zrevrank(timeline_key, status.reblog_of_id)
return false if !rank.nil? && rank < FeedManager::REBLOG_FALLOFF
reblog_rank = redis.zrevrank(reblog_key, status.reblog_of_id)
return false unless reblog_rank.nil?
redis.zadd(timeline_key, status.id, status.id)
redis.zadd(reblog_key, status.id, status.reblog_of_id)
else
redis.zadd(timeline_key, status.id, status.id)
end
true
end
# Removes an individual status from a feed, correctly handling cases
# with reblogs, and returning true if a status was removed. As with
# `add_to_feed`, this does not trigger push updates, so callers must
# do so if appropriate.
def remove_from_feed(timeline_type, account, status)
timeline_key = key(timeline_type, account.id)
reblog_key = key(timeline_type, account.id, 'reblogs')
if status.reblog?
# 1. If the reblogging status is not in the feed, stop.
status_rank = redis.zrevrank(timeline_key, status.id)
return false if status_rank.nil?
# 2. Remove the reblogged status from the `:reblogs` zset.
redis.zrem(reblog_key, status.reblog_of_id)
# 3. Add the reblogged status to the feed using the reblogging
# status' ID as its score, and the reblogged status' ID as its
# value.
redis.zadd(timeline_key, status.id, status.reblog_of_id)
# 4. Remove the reblogging status from the feed (as normal)
end
redis.zrem(timeline_key, status.id)
end
end
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