Merge pull request #17643 from SamSaffron/select_all_perf

PERF: optimise type lookup to avoid invoking procs

1 files changed, 19 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/type/hash_lookup_type_map.rb b/activerecord/lib/active_record/type/hash_lookup_type_map.rb
index bf92680268..2a146d38a9 100644
--- a/activerecord/lib/active_record/type/hash_lookup_type_map.rb
+++ b/activerecord/lib/active_record/type/hash_lookup_type_map.rb
@@ -1,6 +1,12 @@
 module ActiveRecord
   module Type
     class HashLookupTypeMap < TypeMap # :nodoc:
+
+      def initialize
+        @cache = {}
+        super
+      end
+
       delegate :key?, to: :@mapping
 
       def lookup(type, *args)
@@ -8,12 +14,24 @@ module ActiveRecord
       end
 
       def fetch(type, *args, &block)
-        @mapping.fetch(type, block).call(type, *args)
+        cache = (@cache[type] ||= {})
+        resolved = cache[args]
+
+        unless resolved
+          resolved = cache[args] = @mapping.fetch(type, block).call(type, *args)
+        end
+
+        resolved
       end
 
       def alias_type(type, alias_type)
         register_type(type) { |_, *args| lookup(alias_type, *args) }
       end
+
+      def register_type(key, value=nil, &block)
+        @cache = {}
+        super(key, value, &block)
+      end
     end
   end
 end