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