debian-mirror-gitlab/lib/gitlab/cache/request_cache.rb

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2017-09-10 17:25:29 +05:30
module Gitlab
module Cache
# This module provides a simple way to cache values in RequestStore,
# and the cache key would be based on the class name, method name,
# optionally customized instance level values, optionally customized
# method level values, and optional method arguments.
#
# A simple example:
#
# class UserAccess
# extend Gitlab::Cache::RequestCache
#
# request_cache_key do
# [user&.id, project&.id]
# end
#
# request_cache def can_push_to_branch?(ref)
# # ...
# end
# end
#
# This way, the result of `can_push_to_branch?` would be cached in
# `RequestStore.store` based on the cache key. If RequestStore is not
# currently active, then it would be stored in a hash saved in an
# instance variable, so the cache logic would be the same.
# Here's another example using customized method level values:
#
# class Commit
# extend Gitlab::Cache::RequestCache
#
# def author
# User.find_by_any_email(author_email.downcase)
# end
# request_cache(:author) { author_email.downcase }
# end
#
# So that we could have different strategies for different methods
#
module RequestCache
def self.extended(klass)
return if klass < self
extension = Module.new
klass.const_set(:RequestCacheExtension, extension)
klass.prepend(extension)
end
def request_cache_key(&block)
if block_given?
@request_cache_key = block
else
@request_cache_key
end
end
def request_cache(method_name, &method_key_block)
const_get(:RequestCacheExtension).module_eval do
cache_key_method_name = "#{method_name}_cache_key"
define_method(method_name) do |*args|
store =
if RequestStore.active?
RequestStore.store
else
ivar_name = # ! and ? cannot be used as ivar name
"@cache_#{method_name.to_s.tr('!?', "\u2605\u2606")}"
instance_variable_get(ivar_name) ||
instance_variable_set(ivar_name, {})
end
key = __send__(cache_key_method_name, args)
store.fetch(key) { store[key] = super(*args) }
end
define_method(cache_key_method_name) do |args|
klass = self.class
instance_key = instance_exec(&klass.request_cache_key) if
klass.request_cache_key
method_key = instance_exec(&method_key_block) if method_key_block
[klass.name, method_name, *instance_key, *method_key, *args]
.join(':')
end
private cache_key_method_name
end
end
end
end
end