debian-mirror-gitlab/lib/gitlab/repository_cache_adapter.rb

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2018-03-27 19:54:05 +05:30
module Gitlab
module RepositoryCacheAdapter
extend ActiveSupport::Concern
class_methods do
# Wraps around the given method and caches its output in Redis and an instance
# variable.
#
# This only works for methods that do not take any arguments.
def cache_method(name, fallback: nil, memoize_only: false)
original = :"_uncached_#{name}"
alias_method(original, name)
define_method(name) do
cache_method_output(name, fallback: fallback, memoize_only: memoize_only) do
__send__(original) # rubocop:disable GitlabSecurity/PublicSend
end
end
end
end
# RepositoryCache to be used. Should be overridden by the including class
def cache
raise NotImplementedError
end
# Caches the supplied block both in a cache and in an instance variable.
#
# The cache key and instance variable are named the same way as the value of
# the `key` argument.
#
# This method will return `nil` if the corresponding instance variable is also
# set to `nil`. This ensures we don't keep yielding the block when it returns
# `nil`.
#
# key - The name of the key to cache the data in.
# fallback - A value to fall back to in the event of a Git error.
def cache_method_output(key, fallback: nil, memoize_only: false, &block)
ivar = cache_instance_variable_name(key)
if instance_variable_defined?(ivar)
instance_variable_get(ivar)
else
# If the repository doesn't exist and a fallback was specified we return
# that value inmediately. This saves us Rugged/gRPC invocations.
return fallback unless fallback.nil? || cache.repository.exists?
begin
value =
if memoize_only
yield
else
cache.fetch(key, &block)
end
instance_variable_set(ivar, value)
rescue Gitlab::Git::Repository::NoRepository
# Even if the above `#exists?` check passes these errors might still
# occur (for example because of a non-existing HEAD). We want to
# gracefully handle this and not cache anything
fallback
end
end
end
# Expires the caches of a specific set of methods
def expire_method_caches(methods)
methods.each do |key|
cache.expire(key)
ivar = cache_instance_variable_name(key)
remove_instance_variable(ivar) if instance_variable_defined?(ivar)
end
end
private
def cache_instance_variable_name(key)
:"@#{key.to_s.tr('?!', '')}"
end
end
end