1 files changed, 84 insertions, 0 deletions
diff --git a/app/graphql/gitlab_schema.rb b/app/graphql/gitlab_schema.rb
index 06d26309b5b..2e5bdbd79c8 100644
--- a/app/graphql/gitlab_schema.rb
+++ b/app/graphql/gitlab_schema.rb
@@ -1,13 +1,97 @@
 # frozen_string_literal: true
 
 class GitlabSchema < GraphQL::Schema
+  # Currently an IntrospectionQuery has a complexity of 179.
+  # These values will evolve over time.
+  DEFAULT_MAX_COMPLEXITY   = 200
+  AUTHENTICATED_COMPLEXITY = 250
+  ADMIN_COMPLEXITY         = 300
+
+  DEFAULT_MAX_DEPTH = 10
+  AUTHENTICATED_MAX_DEPTH = 15
+
   use BatchLoader::GraphQL
   use Gitlab::Graphql::Authorize
   use Gitlab::Graphql::Present
   use Gitlab::Graphql::Connections
+  use Gitlab::Graphql::GenericTracing
+
+  query_analyzer Gitlab::Graphql::QueryAnalyzers::LoggerAnalyzer.new
 
   query(Types::QueryType)
 
   default_max_page_size 100
+
+  max_complexity DEFAULT_MAX_COMPLEXITY
+  max_depth DEFAULT_MAX_DEPTH
+
   mutation(Types::MutationType)
+
+  class << self
+    def multiplex(queries, **kwargs)
+      kwargs[:max_complexity] ||= max_query_complexity(kwargs[:context])
+
+      queries.each do |query|
+        query[:max_depth] = max_query_depth(kwargs[:context])
+      end
+
+      super(queries, **kwargs)
+    end
+
+    def execute(query_str = nil, **kwargs)
+      kwargs[:max_complexity] ||= max_query_complexity(kwargs[:context])
+      kwargs[:max_depth] ||= max_query_depth(kwargs[:context])
+
+      super(query_str, **kwargs)
+    end
+
+    def id_from_object(object)
+      unless object.respond_to?(:to_global_id)
+        # This is an error in our schema and needs to be solved. So raise a
+        # more meaningfull error message
+        raise "#{object} does not implement `to_global_id`. "\
+              "Include `GlobalID::Identification` into `#{object.class}"
+      end
+
+      object.to_global_id
+    end
+
+    def object_from_id(global_id)
+      gid = GlobalID.parse(global_id)
+
+      unless gid
+        raise Gitlab::Graphql::Errors::ArgumentError, "#{global_id} is not a valid GitLab id."
+      end
+
+      if gid.model_class < ApplicationRecord
+        Gitlab::Graphql::Loaders::BatchModelLoader.new(gid.model_class, gid.model_id).find
+      else
+        gid.find
+      end
+    end
+
+    private
+
+    def max_query_complexity(ctx)
+      current_user = ctx&.fetch(:current_user, nil)
+
+      if current_user&.admin
+        ADMIN_COMPLEXITY
+      elsif current_user
+        AUTHENTICATED_COMPLEXITY
+      else
+        DEFAULT_MAX_COMPLEXITY
+      end
+    end
+
+    def max_query_depth(ctx)
+      current_user = ctx&.fetch(:current_user, nil)
+
+      if current_user
+        AUTHENTICATED_MAX_DEPTH
+      else
+        DEFAULT_MAX_DEPTH
+      end
+    end
+  end
 end