Make serializer lookup configurable (#1757)

test/benchmark/bm_lookup_chain.rb

@@ -0,0 +1,83 @@
+require_relative './benchmarking_support'
+require_relative './app'
+
+time = 10
+disable_gc = true
+ActiveModelSerializers.config.key_transform = :unaltered
+
+module AmsBench
+  module Api
+    module V1
+      class PrimaryResourceSerializer < ActiveModel::Serializer
+        attributes :title, :body
+
+        has_many :has_many_relationships
+      end
+
+      class HasManyRelationshipSerializer < ActiveModel::Serializer
+        attribute :body
+      end
+    end
+  end
+  class PrimaryResourceSerializer < ActiveModel::Serializer
+    attributes :title, :body
+
+    has_many :has_many_relationships
+
+    class HasManyRelationshipSerializer < ActiveModel::Serializer
+      attribute :body
+    end
+  end
+end
+
+resource = PrimaryResource.new(
+  id: 1,
+  title: 'title',
+  body: 'body',
+  has_many_relationships: [
+    HasManyRelationship.new(id: 1, body: 'body1'),
+    HasManyRelationship.new(id: 2, body: 'body1')
+  ]
+)
+
+serialization = lambda do
+  ActiveModelSerializers::SerializableResource.new(resource, serializer: AmsBench::PrimaryResourceSerializer).as_json
+  ActiveModelSerializers::SerializableResource.new(resource, namespace: AmsBench::Api::V1).as_json
+  ActiveModelSerializers::SerializableResource.new(resource).as_json
+end
+
+def clear_cache
+  AmsBench::PrimaryResourceSerializer.serializers_cache.clear
+  AmsBench::Api::V1::PrimaryResourceSerializer.serializers_cache.clear
+  ActiveModel::Serializer.serializers_cache.clear
+end
+
+configurable = lambda do
+  clear_cache
+  Benchmark.ams('Configurable Lookup Chain', time: time, disable_gc: disable_gc, &serialization)
+end
+
+old = lambda do
+  clear_cache
+  module ActiveModel
+    class Serializer
+      def self.serializer_lookup_chain_for(klass, namespace = nil)
+        chain = []
+
+        resource_class_name = klass.name.demodulize
+        resource_namespace = klass.name.deconstantize
+        serializer_class_name = "#{resource_class_name}Serializer"
+
+        chain.push("#{namespace}::#{serializer_class_name}") if namespace
+        chain.push("#{name}::#{serializer_class_name}") if self != ActiveModel::Serializer
+        chain.push("#{resource_namespace}::#{serializer_class_name}")
+        chain
+      end
+    end
+  end
+
+  Benchmark.ams('Old Lookup Chain (v0.10)', time: time, disable_gc: disable_gc, &serialization)
+end
+
+configurable.call
+old.call