gitlab-org--gitlab-foss/lib/gitlab/json_cache.rb

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2018-12-19 08:47:27 -05:00
# frozen_string_literal: true
module Gitlab
class JsonCache
attr_reader :backend, :cache_key_with_version, :namespace
def initialize(options = {})
@backend = options.fetch(:backend, Rails.cache)
@namespace = options.fetch(:namespace, nil)
@cache_key_with_version = options.fetch(:cache_key_with_version, true)
end
def active?
if backend.respond_to?(:active?)
backend.active?
else
true
end
end
def cache_key(key)
expanded_cache_key = [namespace, key].compact
if cache_key_with_version
expanded_cache_key << Rails.version
end
expanded_cache_key.join(':')
end
def expire(key)
backend.delete(cache_key(key))
end
def read(key, klass = nil)
value = backend.read(cache_key(key))
value = parse_value(value, klass) if value
value
end
def write(key, value, options = nil)
backend.write(cache_key(key), value.to_json, options)
end
def fetch(key, options = {}, &block)
klass = options.delete(:as)
value = read(key, klass)
return value unless value.nil?
value = yield
write(key, value, options)
value
end
private
def parse_value(raw, klass)
value = ActiveSupport::JSON.decode(raw)
case value
when Hash then parse_entry(value, klass)
when Array then parse_entries(value, klass)
else
value
end
rescue ActiveSupport::JSON.parse_error
nil
end
def parse_entry(raw, klass)
return unless valid_entry?(raw, klass)
return klass.new(raw) unless klass.ancestors.include?(ActiveRecord::Base)
# When the cached value is a persisted instance of ActiveRecord::Base in
# some cases a relation can return an empty collection becauses scope.none!
# is being applied on ActiveRecord::Associations::CollectionAssociation#scope
# when the new_record? method incorrectly returns false.
#
# See https://gitlab.com/gitlab-org/gitlab-ee/issues/9903#note_145329964
klass
.allocate
.init_with(
"attributes" => attributes_for(klass, raw),
"new_record" => new_record?(raw, klass)
)
end
def attributes_for(klass, raw)
# We have models that leave out some fields from the JSON export for
# security reasons, e.g. models that include the CacheMarkdownField.
# The ActiveRecord::AttributeSet we build from raw does know about
# these columns so we need manually set them.
missing_attributes = (klass.columns.map(&:name) - raw.keys)
missing_attributes.each { |column| raw[column] = nil }
klass.attributes_builder.build_from_database(raw, {})
end
def new_record?(raw, klass)
raw.fetch(klass.primary_key, nil).blank?
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end
def valid_entry?(raw, klass)
return false unless klass && raw.is_a?(Hash)
(raw.keys - klass.attribute_names).empty?
end
def parse_entries(values, klass)
values.map { |value| parse_entry(value, klass) }.compact
end
end
end