diff options
Diffstat (limited to 'lib/gitlab/etag_caching/middleware.rb')
-rw-r--r-- | lib/gitlab/etag_caching/middleware.rb | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/lib/gitlab/etag_caching/middleware.rb b/lib/gitlab/etag_caching/middleware.rb new file mode 100644 index 00000000000..0f24f9bbfde --- /dev/null +++ b/lib/gitlab/etag_caching/middleware.rb @@ -0,0 +1,66 @@ +module Gitlab + module EtagCaching + class Middleware + RESERVED_WORDS = ProjectPathValidator::RESERVED.map { |word| "/#{word}/" }.join('|') + ROUTE_REGEXP = Regexp.union( + %r(^(?!.*(#{RESERVED_WORDS})).*/noteable/issue/\d+/notes\z) + ) + + def initialize(app) + @app = app + end + + def call(env) + return @app.call(env) unless enabled_for_current_route?(env) + Gitlab::Metrics.add_event(:etag_caching_middleware_used) + + etag, cached_value_present = get_etag(env) + if_none_match = env['HTTP_IF_NONE_MATCH'] + + if if_none_match == etag + Gitlab::Metrics.add_event(:etag_caching_cache_hit) + [304, { 'ETag' => etag }, ['']] + else + track_cache_miss(if_none_match, cached_value_present) + + status, headers, body = @app.call(env) + headers['ETag'] = etag + [status, headers, body] + end + end + + private + + def enabled_for_current_route?(env) + ROUTE_REGEXP.match(env['PATH_INFO']) + end + + def get_etag(env) + cache_key = env['PATH_INFO'] + store = Store.new + current_value = store.get(cache_key) + cached_value_present = current_value.present? + + unless cached_value_present + current_value = store.touch(cache_key, only_if_missing: true) + end + + [weak_etag_format(current_value), cached_value_present] + end + + def weak_etag_format(value) + %Q{W/"#{value}"} + end + + def track_cache_miss(if_none_match, cached_value_present) + if if_none_match.blank? + Gitlab::Metrics.add_event(:etag_caching_header_missing) + elsif !cached_value_present + Gitlab::Metrics.add_event(:etag_caching_key_not_found) + else + Gitlab::Metrics.add_event(:etag_caching_resource_changed) + end + end + end + end +end |