cache json parsing

Author: tocsoft

Tocsoft.GraphQLCodeGen.Cli/SchemaIntrospection/JsonIntrospection.cs

@@ -12,10 +12,15 @@ public class JsonIntrospection : IIntrosepctionProvider
     {
         public SchemaSource.SchemaTypes SchemaType => SchemaSource.SchemaTypes.Json;
 
+        static Dictionary<string, string> parseCache = new Dictionary<string, string>();
 
         public Task<string> LoadSchema(SchemaSource source)
         {
-            string schema = ConvertJsonToSchema(File.ReadAllText(source.Location));
+            if (!parseCache.TryGetValue(source.Location, out var schema))
+            {
+                schema = ConvertJsonToSchema(File.ReadAllText(source.Location));
+                parseCache.Add(source.Location, schema);
+            }
             return Task.FromResult(schema);
         }