103 lines
3.1 KiB
Ruby
103 lines
3.1 KiB
Ruby
# frozen_string_literal: true
|
|
|
|
# A collection of events to display in an event list.
|
|
#
|
|
# An EventCollection is meant to be used for displaying events to a user (e.g.
|
|
# in a controller), it's not suitable for building queries that are used for
|
|
# building other queries.
|
|
class EventCollection
|
|
include Gitlab::Utils::StrongMemoize
|
|
|
|
# To prevent users from putting too much pressure on the database by cycling
|
|
# through thousands of events we put a limit on the number of pages.
|
|
MAX_PAGE = 10
|
|
|
|
# projects - An ActiveRecord::Relation object that returns the projects for
|
|
# which to retrieve events.
|
|
# filter - An EventFilter instance to use for filtering events.
|
|
def initialize(projects, limit: 20, offset: 0, filter: nil, groups: nil)
|
|
@projects = projects
|
|
@limit = limit
|
|
@offset = offset
|
|
@filter = filter
|
|
@groups = groups
|
|
end
|
|
|
|
# Returns an Array containing the events.
|
|
def to_a
|
|
return [] if current_page > MAX_PAGE
|
|
|
|
relation = if groups
|
|
project_and_group_events
|
|
else
|
|
relation_with_join_lateral('project_id', projects)
|
|
end
|
|
|
|
relation = paginate_events(relation)
|
|
relation.with_associations.to_a
|
|
end
|
|
|
|
private
|
|
|
|
def project_and_group_events
|
|
project_events = relation_with_join_lateral('project_id', projects)
|
|
group_events = relation_with_join_lateral('group_id', groups)
|
|
|
|
Event.from_union([project_events, group_events]).recent
|
|
end
|
|
|
|
# This relation is built using JOIN LATERAL, producing faster queries than a
|
|
# regular LIMIT + OFFSET approach.
|
|
def relation_with_join_lateral(parent_column, parents)
|
|
parents_for_lateral = parents.select(:id).to_sql
|
|
|
|
lateral = filtered_events
|
|
.limit(limit_for_join_lateral)
|
|
.where("events.#{parent_column} = parents_for_lateral.id") # rubocop:disable GitlabSecurity/SqlInjection
|
|
.to_sql
|
|
|
|
# The outer query does not need to re-apply the filters since the JOIN
|
|
# LATERAL body already takes care of this.
|
|
base_relation
|
|
.from("(#{parents_for_lateral}) parents_for_lateral")
|
|
.joins("JOIN LATERAL (#{lateral}) AS #{Event.table_name} ON true")
|
|
end
|
|
|
|
def filtered_events
|
|
@filter ? @filter.apply_filter(base_relation) : base_relation
|
|
end
|
|
|
|
def paginate_events(events)
|
|
events.limit(@limit).offset(@offset)
|
|
end
|
|
|
|
def base_relation
|
|
# We want to have absolute control over the event queries being built, thus
|
|
# we're explicitly opting out of any default scopes that may be set.
|
|
Event.unscoped.recent
|
|
end
|
|
|
|
def limit_for_join_lateral
|
|
# Applying the OFFSET on the inside of a JOIN LATERAL leads to incorrect
|
|
# results. To work around this we need to increase the inner limit for every
|
|
# page.
|
|
#
|
|
# This means that on page 1 we use LIMIT 20, and an outer OFFSET of 0. On
|
|
# page 2 we use LIMIT 40 and an outer OFFSET of 20.
|
|
@limit + @offset
|
|
end
|
|
|
|
def current_page
|
|
(@offset / @limit) + 1
|
|
end
|
|
|
|
def projects
|
|
@projects.except(:order)
|
|
end
|
|
|
|
def groups
|
|
strong_memoize(:groups) do
|
|
groups.except(:order) if @groups
|
|
end
|
|
end
|
|
end
|