app/lib/feed_manager.rb
# frozen_string_literal: true
require 'singleton'
class FeedManager
include Singleton
include Redisable
# Maximum number of items stored in a single feed
MAX_ITEMS = 800
# Number of items in the feed since last reblog of status
# before the new reblog will be inserted. Must be <= MAX_ITEMS
# or the tracking sets will grow forever
REBLOG_FALLOFF = 40
# Execute block for every active account
# @yield [Account]
# @return [void]
def with_active_accounts(&block)
Account.joins(:user).merge(User.signed_in_recently).find_each(&block)
end
# Redis key of a feed
# @param [Symbol] type
# @param [Integer] id
# @param [Symbol] subtype
# @return [String]
def key(type, id, subtype = nil)
return "feed:#{type}:#{id}" unless subtype
"feed:#{type}:#{id}:#{subtype}"
end
# The filter result of the status to a particular feed
# @param [Symbol] timeline_type
# @param [Status] status
# @param [Account|List] receiver
# @return [void|Symbol] nil, :filter, or :skip_home
def filter(timeline_type, status, receiver)
case timeline_type
when :home
filter_from_home(status, receiver.id, build_crutches(receiver.id, [status]), :home)
when :list
(filter_from_list?(status, receiver) ? :filter : nil) || filter_from_home(status, receiver.account_id, build_crutches(receiver.account_id, [status]), :list)
when :mentions
filter_from_mentions?(status, receiver.id) ? :filter : nil
when :direct
filter_from_direct?(status, receiver.id) ? :filter : nil
when :tags
filter_from_tags?(status, receiver.id, build_crutches(receiver.id, [status])) ? :filter : nil
end
end
# Check if the status should not be added to a feed
# @param [Symbol] timeline_type
# @param [Status] status
# @param [Account|List] receiver
# @return [Boolean]
def filter?(timeline_type, status, receiver)
!!filter(timeline_type, status, receiver)
end
# Add a status to a home feed and send a streaming API update
# @param [Account] account
# @param [Status] status
# @param [Boolean] update
# @return [Boolean]
def push_to_home(account, status, update: false)
return false unless account.user&.signed_in_recently?
return false unless add_to_feed(:home, account.id, status, aggregate_reblogs: account.user&.aggregates_reblogs?)
trim(:home, account.id)
PushUpdateWorker.perform_async(account.id, status.id, "timeline:#{account.id}", { 'update' => update }) if push_update_required?("timeline:#{account.id}")
true
end
# Remove a status from a home feed and send a streaming API update
# @param [Account] account
# @param [Status] status
# @param [Boolean] update
# @return [Boolean]
def unpush_from_home(account, status, update: false)
return false unless remove_from_feed(:home, account.id, status, aggregate_reblogs: account.user&.aggregates_reblogs?)
redis.publish("timeline:#{account.id}", Oj.dump(event: :delete, payload: status.id.to_s)) unless update
true
end
# Add a status to a list feed and send a streaming API update
# @param [List] list
# @param [Status] status
# @param [Boolean] update
# @return [Boolean]
def push_to_list(list, status, update: false)
return false if filter_from_list?(status, list)
return false unless list.account.user&.signed_in_recently?
return false unless add_to_feed(:list, list.id, status, aggregate_reblogs: list.account.user&.aggregates_reblogs?)
trim(:list, list.id)
PushUpdateWorker.perform_async(list.account_id, status.id, "timeline:list:#{list.id}", { 'update' => update }) if push_update_required?("timeline:list:#{list.id}")
true
end
# Remove a status from a list feed and send a streaming API update
# @param [List] list
# @param [Status] status
# @param [Boolean] update
# @return [Boolean]
def unpush_from_list(list, status, update: false)
return false unless remove_from_feed(:list, list.id, status, aggregate_reblogs: list.account.user&.aggregates_reblogs?)
redis.publish("timeline:list:#{list.id}", Oj.dump(event: :delete, payload: status.id.to_s)) unless update
true
end
# Add a status to a linear direct message feed and send a streaming API update
# @param [Account] account
# @param [Status] status
# @return [Boolean]
def push_to_direct(account, status, update: false)
return false unless add_to_feed(:direct, account.id, status)
trim(:direct, account.id)
PushUpdateWorker.perform_async(account.id, status.id, "timeline:direct:#{account.id}") unless update
true
end
# Remove a status from a linear direct message feed and send a streaming API update
# @param [List] list
# @param [Status] status
# @return [Boolean]
def unpush_from_direct(account, status, update: false)
return false unless remove_from_feed(:direct, account.id, status)
redis.publish("timeline:direct:#{account.id}", Oj.dump(event: :delete, payload: status.id.to_s)) unless update
true
end
# Fill a home feed with an account's statuses
# @param [Account] from_account
# @param [Account] into_account
# @return [void]
def merge_into_home(from_account, into_account)
return unless into_account.user&.signed_in_recently?
timeline_key = key(:home, into_account.id)
aggregate = into_account.user&.aggregates_reblogs?
query = from_account.statuses.list_eligible_visibility.includes(:preloadable_poll, :media_attachments, reblog: :account).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
query = query.where('id > ?', oldest_home_score)
end
statuses = query.to_a
crutches = build_crutches(into_account.id, statuses)
statuses.each do |status|
next if filter_from_home(status, into_account.id, crutches)
add_to_feed(:home, into_account.id, status, aggregate_reblogs: aggregate)
end
trim(:home, into_account.id)
end
# Fill a list feed with an account's statuses
# @param [Account] from_account
# @param [List] list
# @return [void]
def merge_into_list(from_account, list)
return unless list.account.user&.signed_in_recently?
timeline_key = key(:list, list.id)
aggregate = list.account.user&.aggregates_reblogs?
query = from_account.statuses.list_eligible_visibility.includes(:preloadable_poll, :media_attachments, reblog: :account).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
query = query.where('id > ?', oldest_home_score)
end
statuses = query.to_a
crutches = build_crutches(list.account_id, statuses)
statuses.each do |status|
next if filter_from_home(status, list.account_id, crutches) || filter_from_list?(status, list)
add_to_feed(:list, list.id, status, aggregate_reblogs: aggregate)
end
trim(:list, list.id)
end
# Remove an account's statuses from a home feed
# @param [Account] from_account
# @param [Account] into_account
# @return [void]
def unmerge_from_home(from_account, into_account)
timeline_key = key(:home, into_account.id)
timeline_status_ids = redis.zrange(timeline_key, 0, -1)
from_account.statuses.select(:id, :reblog_of_id).where(id: timeline_status_ids).reorder(nil).find_each do |status|
remove_from_feed(:home, into_account.id, status, aggregate_reblogs: into_account.user&.aggregates_reblogs?)
end
end
# Remove an account's statuses from a list feed
# @param [Account] from_account
# @param [List] list
# @return [void]
def unmerge_from_list(from_account, list)
timeline_key = key(:list, list.id)
timeline_status_ids = redis.zrange(timeline_key, 0, -1)
from_account.statuses.select(:id, :reblog_of_id).where(id: timeline_status_ids).reorder(nil).find_each do |status|
remove_from_feed(:list, list.id, status, aggregate_reblogs: list.account.user&.aggregates_reblogs?)
end
end
# Remove a tag's statuses from a home feed
# @param [Tag] from_tag
# @param [Account] into_account
# @return [void]
def unmerge_tag_from_home(from_tag, into_account)
timeline_key = key(:home, into_account.id)
timeline_status_ids = redis.zrange(timeline_key, 0, -1)
# This is a bit tricky because we need posts tagged with this hashtag that are not
# also tagged with another followed hashtag or from a followed user
scope = from_tag.statuses
.where(id: timeline_status_ids)
.where.not(account: into_account)
.where.not(account: into_account.following)
.tagged_with_none(TagFollow.where(account: into_account).pluck(:tag_id))
scope.select(:id, :reblog_of_id).reorder(nil).find_each do |status|
remove_from_feed(:home, into_account.id, status, aggregate_reblogs: into_account.user&.aggregates_reblogs?)
end
end
# Clear all statuses from or mentioning target_account from a home feed
# @param [Account] account
# @param [Account] target_account
# @return [void]
def clear_from_home(account, target_account)
timeline_key = key(:home, account.id)
timeline_status_ids = redis.zrange(timeline_key, 0, -1)
statuses = Status.where(id: timeline_status_ids).select(:id, :reblog_of_id, :account_id).to_a
reblogged_ids = Status.where(id: statuses.filter_map(&:reblog_of_id), account: target_account).pluck(:id)
with_mentions_ids = Mention.active.where(status_id: statuses.flat_map { |s| [s.id, s.reblog_of_id] }.compact, account: target_account).pluck(:status_id)
target_statuses = statuses.select do |status|
status.account_id == target_account.id || reblogged_ids.include?(status.reblog_of_id) || with_mentions_ids.include?(status.id) || with_mentions_ids.include?(status.reblog_of_id)
end
target_statuses.each do |status|
unpush_from_home(account, status)
end
end
# Clear all statuses from or mentioning target_account from a list feed
# @param [List] list
# @param [Account] target_account
# @return [void]
def clear_from_list(list, target_account)
timeline_key = key(:list, list.id)
timeline_status_ids = redis.zrange(timeline_key, 0, -1)
statuses = Status.where(id: timeline_status_ids).select(:id, :reblog_of_id, :account_id).to_a
reblogged_ids = Status.where(id: statuses.filter_map(&:reblog_of_id), account: target_account).pluck(:id)
with_mentions_ids = Mention.active.where(status_id: statuses.flat_map { |s| [s.id, s.reblog_of_id] }.compact, account: target_account).pluck(:status_id)
target_statuses = statuses.select do |status|
status.account_id == target_account.id || reblogged_ids.include?(status.reblog_of_id) || with_mentions_ids.include?(status.id) || with_mentions_ids.include?(status.reblog_of_id)
end
target_statuses.each do |status|
unpush_from_list(list, status)
end
end
# Clear all statuses from or mentioning target_account from an account's lists
# @param [Account] account
# @param [Account] target_account
# @return [void]
def clear_from_lists(account, target_account)
List.where(account: account).find_each do |list|
clear_from_list(list, target_account)
end
end
# Populate home feed of account from scratch
# @param [Account] account
# @return [void]
def populate_home(account)
limit = FeedManager::MAX_ITEMS / 2
aggregate = account.user&.aggregates_reblogs?
timeline_key = key(:home, account.id)
account.statuses.limit(limit).each do |status|
add_to_feed(:home, account.id, status, aggregate_reblogs: aggregate)
end
account.following.includes(:account_stat).reorder(nil).find_each do |target_account|
if redis.zcard(timeline_key) >= limit
oldest_home_score = redis.zrange(timeline_key, 0, 0, with_scores: true).first.last.to_i
last_status_score = Mastodon::Snowflake.id_at(target_account.last_status_at)
# If the feed is full and this account has not posted more recently
# than the last item on the feed, then we can skip the whole account
# because none of its statuses would stay on the feed anyway
next if last_status_score < oldest_home_score
end
statuses = target_account.statuses.list_eligible_visibility.includes(:preloadable_poll, :media_attachments, :account, reblog: :account).limit(limit)
crutches = build_crutches(account.id, statuses)
statuses.each do |status|
next if filter_from_home(status, account.id, crutches)
add_to_feed(:home, account.id, status, aggregate_reblogs: aggregate)
end
trim(:home, account.id)
end
end
# Populate direct feed of account from scratch
# @param [Account] account
# @return [void]
def populate_direct_feed(account)
added = 0
limit = FeedManager::MAX_ITEMS / 2
max_id = nil
loop do
statuses = Status.as_direct_timeline(account, limit, max_id)
break if statuses.empty?
statuses.each do |status|
next if filter_from_direct?(status, account)
added += 1 if add_to_feed(:direct, account.id, status)
end
break unless added.zero?
max_id = statuses.last.id
end
end
# Completely clear multiple feeds at once
# @param [Symbol] type
# @param [Array<Integer>] ids
# @return [void]
def clean_feeds!(type, ids)
reblogged_id_sets = {}
redis.pipelined do |pipeline|
ids.each do |feed_id|
reblog_key = key(type, feed_id, 'reblogs')
# We collect a future for this: we don't block while getting
# it, but we can iterate over it later.
reblogged_id_sets[feed_id] = pipeline.zrange(reblog_key, 0, -1)
pipeline.del(key(type, feed_id), reblog_key)
end
end
# Remove all of the reblog tracking keys we just removed the
# references to.
keys_to_delete = reblogged_id_sets.flat_map do |feed_id, future|
future.value.map do |reblogged_id|
key(type, feed_id, "reblogs:#{reblogged_id}")
end
end
redis.del(keys_to_delete) unless keys_to_delete.empty?
nil
end
private
# Trim a feed to maximum size by removing older items
# @param [Symbol] type
# @param [Integer] timeline_id
# @return [void]
def trim(type, timeline_id)
timeline_key = key(type, timeline_id)
reblog_key = key(type, timeline_id, 'reblogs')
# Remove any items past the MAX_ITEMS'th entry in our feed
redis.zremrangebyrank(timeline_key, 0, -(FeedManager::MAX_ITEMS + 1))
# 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
falloff_range = redis.zrevrange(timeline_key, falloff_rank, falloff_rank, with_scores: true)
falloff_score = falloff_range&.first&.last&.to_i
return if falloff_score.nil?
# Get any reblogs we might have to clean up after.
redis.zrangebyscore(reblog_key, 0, falloff_score).each do |reblogged_id|
# Remove it from the set of reblogs we're tracking *first* to avoid races.
redis.zrem(reblog_key, reblogged_id)
# Just drop any set we might have created to track additional reblogs.
# This means that if this reblog is deleted, we won't automatically insert
# another reblog, but also that any new reblog can be inserted into the
# feed.
redis.del(key(type, timeline_id, "reblogs:#{reblogged_id}"))
end
end
# Check if there is a streaming API client connected
# for the given feed
# @param [String] timeline_key
# @return [Boolean]
def push_update_required?(timeline_key)
redis.exists?("subscribed:#{timeline_key}")
end
# Check if the account is blocking or muting any of the given accounts
# @param [Integer] receiver_id
# @param [Array<Integer>] account_ids
# @param [Symbol] context
def blocks_or_mutes?(receiver_id, account_ids, context)
Block.where(account_id: receiver_id, target_account_id: account_ids).any? ||
(context == :home ? Mute.where(account_id: receiver_id, target_account_id: account_ids).any? : Mute.where(account_id: receiver_id, target_account_id: account_ids, hide_notifications: true).any?)
end
# Check if status should not be added to the home feed
# @param [Status] status
# @param [Integer] receiver_id
# @param [Hash] crutches
# @return [void|Symbol] nil, :skip_home, or :filter
def filter_from_home(status, receiver_id, crutches, timeline_type = :home)
return if receiver_id == status.account_id
return :filter if status.reply? && (status.in_reply_to_id.nil? || status.in_reply_to_account_id.nil?)
return :skip_home if timeline_type != :list && crutches[:exclusive_list_users][status.account_id].present?
return :filter if crutches[:languages][status.account_id].present? && status.language.present? && !crutches[:languages][status.account_id].include?(status.language)
check_for_blocks = crutches[:active_mentions][status.id] || []
check_for_blocks.push(status.account_id)
if status.reblog?
check_for_blocks.push(status.reblog.account_id)
check_for_blocks.concat(crutches[:active_mentions][status.reblog_of_id] || [])
end
return :filter if check_for_blocks.any? { |target_account_id| crutches[:blocking][target_account_id] || crutches[:muting][target_account_id] }
return :filter if crutches[:blocked_by][status.account_id]
if status.reply? && !status.in_reply_to_account_id.nil? # Filter out if it's a reply
should_filter = !crutches[:following][status.in_reply_to_account_id] # 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
elsif status.reblog? # Filter out a reblog
should_filter = crutches[:hiding_reblogs][status.account_id] # if the reblogger's reblogs are suppressed
should_filter ||= crutches[:blocked_by][status.reblog.account_id] # or if the author of the reblogged status is blocking me
should_filter ||= crutches[:domain_blocking][status.reblog.account.domain] # or the author's domain is blocked
else
should_filter = false
end
should_filter ? :filter : nil
end
# Check if status should not be added to the mentions feed
# @see NotifyService
# @param [Status] status
# @param [Integer] receiver_id
# @return [Boolean]
def filter_from_mentions?(status, receiver_id)
return true if receiver_id == status.account_id
# This filter is called from NotifyService, but already after the sender of
# the notification has been checked for mute/block. Therefore, it's not
# necessary to check the author of the toot for mute/block again
check_for_blocks = status.active_mentions.pluck(:account_id)
check_for_blocks.push(status.in_reply_to_account) if status.reply? && !status.in_reply_to_account_id.nil?
blocks_or_mutes?(receiver_id, check_for_blocks, :mentions) # Filter if it's from someone I blocked, in reply to someone I blocked, or mentioning someone I blocked (or muted)
end
# Check if status should not be added to the linear direct message feed
# @param [Status] status
# @param [Integer] receiver_id
# @return [Boolean]
def filter_from_direct?(status, receiver_id)
return false if receiver_id == status.account_id
filter_from_mentions?(status, receiver_id)
end
# Check if status should not be added to the list feed
# @param [Status] status
# @param [List] list
# @return [Boolean]
def filter_from_list?(status, list)
if status.reply? && status.in_reply_to_account_id != status.account_id # Status is a reply to account other than status account
should_filter = status.in_reply_to_account_id != list.account_id # Status replies to account id other than list account
should_filter &&= !list.show_followed? # List show_followed? is false
should_filter &&= !(list.show_list? && ListAccount.exists?(list_id: list.id, account_id: status.in_reply_to_account_id)) # If show_list? true, check for a ListAccount with list and reply to account
return !!should_filter
end
false
end
# Check if a status should not be added to the home feed when it comes
# from a followed hashtag
# @param [Status] status
# @param [Integer] receiver_id
# @param [Hash] crutches
# @return [Boolean]
def filter_from_tags?(status, receiver_id, crutches)
receiver_id == status.account_id || # Receiver is status account?
((crutches[:active_mentions][status.id] || []) + [status.account_id]) # For mentioned accounts or status account:
.any? { |target_account_id| crutches[:blocking][target_account_id] || crutches[:muting][target_account_id] } || # - Target account is muted or blocked?
crutches[:blocked_by][status.account_id] || # Blocked by status account?
crutches[:domain_blocking][status.account.domain] # Blocking domain of status account?
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.
# @param [Symbol] timeline_type
# @param [Integer] account_id
# @param [Status] status
# @param [Boolean] aggregate_reblogs
# @return [Boolean]
def add_to_feed(timeline_type, account_id, status, aggregate_reblogs: true)
timeline_key = key(timeline_type, account_id)
reblog_key = key(timeline_type, account_id, 'reblogs')
if status.reblog? && (aggregate_reblogs.nil? || aggregate_reblogs)
# 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
# The ordered set at `reblog_key` holds statuses which have a reblog
# in the top `REBLOG_FALLOFF` statuses of the timeline
if redis.zadd(reblog_key, status.id, status.reblog_of_id, nx: true)
# This is not something we've already seen reblogged, so we
# can just add it to the feed (and note that we're reblogging it).
redis.zadd(timeline_key, status.id, status.id)
else
# Another reblog of the same status was already in the
# REBLOG_FALLOFF most recent statuses, so we note that this
# is an "extra" reblog, by storing it in reblog_set_key.
reblog_set_key = key(timeline_type, account_id, "reblogs:#{status.reblog_of_id}")
redis.sadd(reblog_set_key, status.id)
return false
end
else
# A reblog may reach earlier than the original status because of the
# delay of the worker delivering the original status, the late addition
# by merging timelines, and other reasons.
# If such a reblog already exists, just do not re-insert it into the feed.
return false unless redis.zscore(reblog_key, status.id).nil?
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.
# @param [Symbol] timeline_type
# @param [Integer] account_id
# @param [Status] status
# @param [Boolean] aggregate_reblogs
# @return [Boolean]
def remove_from_feed(timeline_type, account_id, status, aggregate_reblogs: true)
timeline_key = key(timeline_type, account_id)
reblog_key = key(timeline_type, account_id, 'reblogs')
if status.reblog? && (aggregate_reblogs.nil? || aggregate_reblogs)
# 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 reblog from set of this status's reblogs.
reblog_set_key = key(timeline_type, account_id, "reblogs:#{status.reblog_of_id}")
redis.srem(reblog_set_key, status.id)
redis.zrem(reblog_key, status.reblog_of_id)
# 3. Re-insert another reblog or original into the feed if one
# remains in the set. We could pick a random element, but this
# set should generally be small, and it seems ideal to show the
# oldest potential such reblog.
other_reblog = redis.smembers(reblog_set_key).map(&:to_i).min
redis.zadd(timeline_key, other_reblog, other_reblog) if other_reblog
redis.zadd(reblog_key, other_reblog, status.reblog_of_id) if other_reblog
# 4. Remove the reblogging status from the feed (as normal)
# (outside conditional)
else
# If the original is getting deleted, no use for reblog references
redis.del(key(timeline_type, account_id, "reblogs:#{status.id}"))
redis.zrem(reblog_key, status.id)
end
redis.zrem(timeline_key, status.id)
end
# Pre-fetch various objects and relationships for given statuses that
# are going to be checked by the filtering methods
# @param [Integer] receiver_id
# @param [Array<Status>] statuses
# @return [Hash]
def build_crutches(receiver_id, statuses)
crutches = {}
crutches[:active_mentions] = crutches_active_mentions(statuses)
check_for_blocks = statuses.flat_map do |s|
arr = crutches[:active_mentions][s.id] || []
arr.push(s.account_id)
if s.reblog? && s.reblog.present?
arr.push(s.reblog.account_id)
arr.concat(crutches[:active_mentions][s.reblog_of_id] || [])
end
arr
end
lists = List.where(account_id: receiver_id, exclusive: true)
crutches[:following] = Follow.where(account_id: receiver_id, target_account_id: statuses.filter_map(&:in_reply_to_account_id)).pluck(:target_account_id).index_with(true)
crutches[:languages] = Follow.where(account_id: receiver_id, target_account_id: statuses.map(&:account_id)).pluck(:target_account_id, :languages).to_h
crutches[:hiding_reblogs] = Follow.where(account_id: receiver_id, target_account_id: statuses.filter_map { |s| s.account_id if s.reblog? }, show_reblogs: false).pluck(:target_account_id).index_with(true)
crutches[:blocking] = Block.where(account_id: receiver_id, target_account_id: check_for_blocks).pluck(:target_account_id).index_with(true)
crutches[:muting] = Mute.where(account_id: receiver_id, target_account_id: check_for_blocks).pluck(:target_account_id).index_with(true)
crutches[:domain_blocking] = AccountDomainBlock.where(account_id: receiver_id, domain: statuses.flat_map { |s| [s.account.domain, s.reblog&.account&.domain] }.compact).pluck(:domain).index_with(true)
crutches[:blocked_by] = Block.where(target_account_id: receiver_id, account_id: statuses.map { |s| [s.account_id, s.reblog&.account_id] }.flatten.compact).pluck(:account_id).index_with(true)
crutches[:exclusive_list_users] = ListAccount.where(list: lists, account_id: statuses.map(&:account_id)).pluck(:account_id).index_with(true)
crutches
end
def crutches_active_mentions(statuses)
Mention
.active
.where(status_id: statuses.flat_map { |status| [status.id, status.reblog_of_id] }.compact)
.pluck(:status_id, :account_id)
.each_with_object({}) { |(id, account_id), mapping| (mapping[id] ||= []).push(account_id) }
end
end