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author | Alejandro RodrÃguez <alejorro70@gmail.com> | 2018-03-07 03:12:29 +0300 |
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committer | Alejandro RodrÃguez <alejorro70@gmail.com> | 2018-03-07 03:12:29 +0300 |
commit | 5171e2f3d4fdc681a58e11f9615afa968324a278 (patch) | |
tree | 256a12ed77a7a6aabff58bc267a70d476cc4dfa7 /lib/gitlab/repository_cache_adapter.rb | |
parent | 35f6efaee05835b75e605e1f269e57a8d6daf3fa (diff) |
Refactor RepositoryCache to make it usable in other classes
Diffstat (limited to 'lib/gitlab/repository_cache_adapter.rb')
-rw-r--r-- | lib/gitlab/repository_cache_adapter.rb | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/lib/gitlab/repository_cache_adapter.rb b/lib/gitlab/repository_cache_adapter.rb new file mode 100644 index 00000000000..7f64a8c9e46 --- /dev/null +++ b/lib/gitlab/repository_cache_adapter.rb @@ -0,0 +1,84 @@ +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 |