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# frozen_string_literal: true
module Gitlab
module ImportExport
module Base
# Base class for Group & Project Object Builders.
# This class is not intended to be used on its own but
# rather inherited from.
#
# Cache keeps 1000 entries at most, 1000 is chosen based on:
# - one cache entry uses around 0.5K memory, 1000 items uses around 500K.
# (leave some buffer it should be less than 1M). It is afforable cost for project import.
# - for projects in Gitlab.com, it seems 1000 entries for labels/milestones is enough.
# For example, gitlab has ~970 labels and 26 milestones.
LRU_CACHE_SIZE = 1000
class ObjectBuilder
def self.build(*args)
new(*args).find
end
def initialize(klass, attributes)
@klass = klass.ancestors.include?(Label) ? Label : klass
@attributes = attributes
if Gitlab::SafeRequestStore.active?
@lru_cache = cache_from_request_store
@cache_key = [klass, attributes]
end
end
def find
find_with_cache do
find_object || klass.create(prepare_attributes)
end
end
protected
def where_clauses
raise NotImplementedError
end
# attributes wrapped in a method to be
# adjusted in sub-class if needed
def prepare_attributes
attributes
end
def find_with_cache(key = cache_key)
return yield unless lru_cache && key
lru_cache[key] ||= yield
end
private
attr_reader :klass, :attributes, :lru_cache, :cache_key
def cache_from_request_store
Gitlab::SafeRequestStore[:lru_cache] ||= LruRedux::Cache.new(LRU_CACHE_SIZE)
end
def find_object
klass.find_by(where_clause)
end
def where_clause
where_clauses.reduce(:and)
end
def table
@table ||= klass.arel_table
end
# Returns Arel clause:
# `"{table_name}"."{attrs.keys[0]}" = '{attrs.values[0]} AND {table_name}"."{attrs.keys[1]}" = '{attrs.values[1]}"`
# from the given Hash of attributes.
def attrs_to_arel(attrs)
attrs.map do |key, value|
table[key].eq(value)
end.reduce(:and)
end
# Returns Arel clause `"{table_name}"."title" = '{attributes['title']}'`
# if attributes has 'title key, otherwise `nil`.
def where_clause_for_title
attrs_to_arel(attributes.slice('title'))
end
# Returns Arel clause `"{table_name}"."description" = '{attributes['description']}'`
# if attributes has 'description key, otherwise `nil`.
def where_clause_for_description
attrs_to_arel(attributes.slice('description'))
end
# Returns Arel clause `"{table_name}"."created_at" = '{attributes['created_at']}'`
# if attributes has 'created_at key, otherwise `nil`.
def where_clause_for_created_at
attrs_to_arel(attributes.slice('created_at'))
end
end
end
end
end
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