Implement cache in schema loading

lib/committee/drivers.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'digest'
+
 module Committee
   module Drivers
     # Gets a driver instance from the specified name. Raises ArgumentError for
@@ -36,13 +38,16 @@ def self.load_from_yaml(schema_path, parser_options: {})
     # @param [String] schema_path
     # @return [Committee::Driver]
     def self.load_from_file(schema_path, parser_options: {})
-      case File.extname(schema_path)
-      when '.json'
-        load_from_json(schema_path, parser_options: parser_options)
-      when '.yaml', '.yml'
-        load_from_yaml(schema_path, parser_options: parser_options)
-      else
-        raise "Committee only supports the following file extensions: '.json', '.yaml', '.yml'"
+      @__load_from_file_cache ||= {}
+      @__load_from_file_cache[cache_key(schema_path, parser_options)] ||= begin
+        case File.extname(schema_path)
+        when '.json'
+          load_from_json(schema_path, parser_options: parser_options)
+        when '.yaml', '.yml'
+          load_from_yaml(schema_path, parser_options: parser_options)
+        else
+          raise "Committee only supports the following file extensions: '.json', '.yaml', '.yml'"
+        end
       end
     end
 
@@ -74,6 +79,17 @@ def self.load_from_data(hash, schema_path = nil, parser_options: {})
       # TODO: in the future, pass `opts` here and allow optionality in other drivers?
       driver.parse(hash)
     end
+
+    class << self
+      private
+
+      def cache_key(schema_path, parser_options)
+        [
+          File.exist?(schema_path) ? Digest::MD5.hexdigest(File.read(schema_path)) : nil,
+          parser_options.hash,
+        ].join('_')
+      end
+    end
   end
 end
 

test/drivers_test.rb

@@ -67,6 +67,35 @@
       end
       assert_equal "Committee only supports the following file extensions: '.json', '.yaml', '.yml'", e.message
     end
+
+    describe 'cache behavior' do
+      describe 'when loading the same file' do
+        it 'returns the same object when the options are identical' do
+          assert_equal(
+            Committee::Drivers.load_from_file(open_api_3_schema_path, parser_options:{strict_reference_validation: true}).object_id,
+            Committee::Drivers.load_from_file(open_api_3_schema_path, parser_options:{strict_reference_validation: true}).object_id,
+          )
+        end
+
+        it 'returns different objects if the options are different' do
+          refute_equal(
+            Committee::Drivers.load_from_file(open_api_3_schema_path, parser_options:{strict_reference_validation: true}).object_id,
+            Committee::Drivers.load_from_file(open_api_3_schema_path, parser_options:{strict_reference_validation: false}).object_id,
+          )
+        end
+
+        it 'returns different objects if the file contents have changed' do
+          object_id = Committee::Drivers.load_from_file(open_api_3_schema_path, parser_options:{strict_reference_validation: true}).object_id
+          original_file_contents = File.read(open_api_3_schema_path)
+          File.write(open_api_3_schema_path, original_file_contents + "\n")
+          refute_equal(
+            Committee::Drivers.load_from_file(open_api_3_schema_path, parser_options:{strict_reference_validation: true}).object_id,
+            object_id,
+          )
+          File.write(open_api_3_schema_path, original_file_contents)
+        end
+      end
+    end
   end
 
   describe 'load_from_json(schema_path)' do