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# frozen_string_literal: true
class ActivityPub::FetchCollectionItemsService < BaseService
include JsonLdHelper
COOLDOWN = 30.minutes
# Fetches objects in a collection from a URI or hash and queues them for processing.
# @param collection [Hash, String] Collection hash or URI
# @param account [Account] Owner of the collection
# @param page_limit [Integer] (10) Maximum number of pages to fetch from the collection.
# @param item_limit [Integer] (100) Maximum number of items to fetch from the collection.
# @option options [Boolean] :every_page (false) Whether to fetch every page in the collection,
# even if its items have been previously fetched. By default, fetching will stop if all the
# items on any page have already been fetched.
# @option options [Boolean] :look_ahead (false) Whether to check the next page for unfetched
# items if the current page's items have been previously fetched. If there are unfetched
# items on the next page, fetching will continue.
# @option options [Boolean] :skip_cooldown (false) Skip the fetch cooldown period on the a
# collection URI (e.g., for account migration).
# @option options [Boolean] :include_boosts (false) Whether to skip boosts. Including these
# will cause a LOT of server traffic.
# @return [void]
# @raise [Mastodon::RaceConditionError] Collection is already being fetched.
# @raise [Mastodon::UnexpectedResponseError] Server returned an error while fetching a page.
def call(collection, account, page_limit: 10, item_limit: 100, **options)
uri = value_or_id(collection)
return if uri.blank? || ActivityPub::TagManager.instance.local_uri?(uri)
uri = collection['partOf'] if collection.is_a?(Hash) && collection['partOf'].present?
@account = account
@account = account_from_uri(uri) if @account.blank?
set_fetch_account
return if !options[:skip_cooldown] && Redis.current.get("fetch_collection_cooldown:#{uri}")
collection = fetch_collection(collection)
return if collection.blank?
if @account.blank?
@account = account_from_uri(collection['partOf'].presence || collection['id'])
set_fetch_account
end
fetch_collection_pages(collection, page_limit, item_limit, **options)
end
private
def lock_options(uri)
{ redis: Redis.current, key: "fetch_collection:#{uri}" }
end
def set_fetch_account
@on_behalf_of = @account.present? ? @account.followers.local.random.first : nil
end
def account_from_uri(uri)
ActivityPub::TagManager.instance.uri_to_resource(uri, Account)
end
def account_id_from_uri(uri)
return if uri.blank?
Rails.cache.fetch("account_id_from_uri:#{uri}", expires_in: 10.minutes) do
account_from_uri(uri)&.id
end
end
def valid_item?(item)
item.is_a?(Hash) &&
!invalid_uri?(item['id']) &&
(item['attributedTo'].present? || item['actor'].present?) && (
item['object'].blank? || item['type'] == 'Create' && !invalid_uri?(value_or_id(item['object']))
)
end
def uri_with_account_id(item)
object = item['object'].presence || item
[value_or_id(object), object.is_a?(Hash) ? account_id_from_uri(object['attributedTo']) : account_id_from_uri(item['actor'])]
end
def invalid_uri?(uri)
unsupported_uri_scheme?(uri) || !uri_allowed?(uri) || ActivityPub::TagManager.instance.local_uri?(uri)
end
def fetch_collection(collection_or_uri)
return (collection_or_uri['id'].present? ? collection_or_uri : nil) if collection_or_uri.is_a?(Hash)
return if !collection_or_uri.is_a?(String) || invalid_origin?(collection_or_uri)
fetch_resource_without_id_validation(collection_or_uri, @on_behalf_of, true)
end
def fetch_collection_pages(collection, page_limit, item_limit, **options)
uri = collection['partOf'].presence || collection['id']
cooldown_key = "fetch_collection_cooldown:#{uri}"
return if !options[:skip_cooldown] && Redis.current.get(cooldown_key)
Redis.current.set(cooldown_key, 1, ex: COOLDOWN)
RedisLock.acquire(lock_options(uri)) do |lock|
raise Mastodon::RaceConditionError unless lock.acquired?
page = CollectionPage.find_or_create_by(uri: uri, account: @account)
every_page = options[:every_page]
if page.next.present?
collection = fetch_collection(page.next)
fetch_collection_items(collection, page, page_limit, item_limit, **options)
every_page = false
end
uri = collection['first'].presence || collection['id']
page.update!(next: uri)
collection = fetch_collection(uri) if collection['id'] != uri
fetch_collection_items(collection, page, page_limit, item_limit, **options.merge({ every_page: every_page }))
end
end
def fetch_collection_items(collection, page, page_limit, item_limit, **options)
page_count = 0
item_count = 0
seen_pages = Set[page.next]
have_items = false
while collection.present? && collection['type'].present?
batch = case collection['type']
when 'Collection', 'CollectionPage'
collection['items']
when 'OrderedCollection', 'OrderedCollectionPage'
collection['orderedItems']
end
break unless batch.is_a?(Array)
batch_size = [batch.count, item_limit - item_count].min
batch = batch.take(batch_size).select { |item| valid_item?(item) }.map { |item| uri_with_account_id(item) }
result = CollectionItem.import([:uri, :account_id], batch, validate: false, on_duplicate_key_ignore: true)
if !options[:every_page] && result.ids.blank?
break if have_items || !options[:look_ahead]
have_items = true
elsif have_items
have_items = false
end
item_count += result.ids.count
page_count += 1
next_page = collection['next']
break unless item_count < item_limit && page_count < page_limit && next_page.present?
break if seen_pages.include?(next_page)
sleep [page_count.to_f / 5, 1].min
seen_pages << next_page
page.update!(next: next_page)
collection = fetch_collection(next_page)
end
page.delete
ActivityPub::ProcessCollectionItemsWorker.perform_async
end
end
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