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# frozen_string_literal: true
module Gitlab
module Cache
module Helpers
# @return [ActiveSupport::Duration]
DEFAULT_EXPIRY = 1.day
# @return [ActiveSupport::Cache::Store]
def cache
Rails.cache
end
def render_cached(obj_or_collection, with:, cache_context: -> (_) { current_user&.cache_key }, expires_in: Gitlab::Cache::Helpers::DEFAULT_EXPIRY, **presenter_args)
json =
if obj_or_collection.is_a?(Enumerable)
cached_collection(
obj_or_collection,
presenter: with,
presenter_args: presenter_args,
context: cache_context,
expires_in: expires_in
)
else
cached_object(
obj_or_collection,
presenter: with,
presenter_args: presenter_args,
context: cache_context,
expires_in: expires_in
)
end
render Gitlab::Json::PrecompiledJson.new(json)
end
private
# Optionally uses a `Proc` to add context to a cache key
#
# @param object [Object] must respond to #cache_key
# @param context [Proc] a proc that will be called with the object as an argument, and which should return a
# string or array of strings to be combined into the cache key
# @return [String]
def contextual_cache_key(presenter, object, context)
return object.cache_key if context.nil?
[presenter.class.name, object.cache_key, context.call(object)].flatten.join(":")
end
# Used for fetching or rendering a single object
#
# @param object [Object] the object to render
# @param presenter [Grape::Entity]
# @param presenter_args [Hash] keyword arguments to be passed to the entity
# @param context [Proc]
# @param expires_in [ActiveSupport::Duration, Integer] an expiry time for the cache entry
# @return [String]
def cached_object(object, presenter:, presenter_args:, context:, expires_in:)
cache.fetch(contextual_cache_key(presenter, object, context), expires_in: expires_in) do
Gitlab::Json.dump(presenter.represent(object, **presenter_args).as_json)
end
end
# Used for fetching or rendering multiple objects
#
# @param objects [Enumerable<Object>] the objects to render
# @param presenter [Grape::Entity]
# @param presenter_args [Hash] keyword arguments to be passed to the entity
# @param context [Proc]
# @param expires_in [ActiveSupport::Duration, Integer] an expiry time for the cache entry
# @return [Array<String>]
def cached_collection(collection, presenter:, presenter_args:, context:, expires_in:)
json = fetch_multi(presenter, collection, context: context, expires_in: expires_in) do |obj|
Gitlab::Json.dump(presenter.represent(obj, **presenter_args).as_json)
end
json.values
end
# An adapted version of ActiveSupport::Cache::Store#fetch_multi.
#
# The original method only provides the missing key to the block,
# not the missing object, so we have to create a map of cache keys
# to the objects to allow us to pass the object to the missing value
# block.
#
# The result is that this is functionally identical to `#fetch`.
def fetch_multi(presenter, *objs, context:, **kwargs)
objs.flatten!
map = multi_key_map(presenter, objs, context: context)
# TODO: `contextual_cache_key` should be constructed based on the guideline https://docs.gitlab.com/ee/development/redis.html#multi-key-commands.
Gitlab::Instrumentation::RedisClusterValidator.allow_cross_slot_commands do
cache.fetch_multi(*map.keys, **kwargs) do |key|
yield map[key]
end
end
end
# @param objects [Enumerable<Object>] objects which _must_ respond to `#cache_key`
# @param context [Proc] a proc that can be called to help generate each cache key
# @return [Hash]
def multi_key_map(presenter, objects, context:)
objects.index_by do |object|
contextual_cache_key(presenter, object, context)
end
end
end
end
end
|
