tweak new code, add release note (#718)

docs/release-notes.md

@@ -6,6 +6,7 @@
   * Mod warnings are now listed alphabetically.
   * MacOS files starting with `._` are now ignored and can no longer cause skipped mods.
   * Simplified paranoid warning logs and reduced their log level.
+  * Reduced startup time when loading mod DLLs (thanks to ZaneYork!).
   * Fixed `BadImageFormatException` error detection.
   * Fixed black maps on Android for mods which use `.tmx` files.
 

src/SMAPI/Framework/ModLoading/Framework/RecursiveRewriter.cs

@@ -57,16 +57,18 @@ namespace StardewModdingAPI.Framework.ModLoading.Framework
         /// <returns>Returns whether the module was modified.</returns>
         public bool RewriteModule()
         {
-            Tuple<bool,Exception> aggregateResult = this.Module.GetTypes()
-                .AsParallel().WithExecutionMode(ParallelExecutionMode.ForceParallelism)
+            // rewrite each type in the assembly, tracking whether any type was rewritten (Item1)
+            // and any exception that occurred during rewriting (Item2).
+            Tuple<bool, Exception> result = this.Module
+                .GetTypes()
+                .Where(type => type.BaseType != null) // skip special types like <Module>
+                .AsParallel()
+                .WithExecutionMode(ParallelExecutionMode.ForceParallelism)
                 .Select(type =>
                 {
+                    bool anyRewritten = false;
                     try
                     {
-                        bool anyRewritten = false;
-                        if (type.BaseType == null)
-                            return new Tuple<bool, Exception>(anyRewritten, null); // special type like <Module>
-
                         anyRewritten |= this.RewriteCustomAttributes(type.CustomAttributes);
                         anyRewritten |= this.RewriteGenericParameters(type.GenericParameters);
 
@@ -112,19 +114,20 @@ namespace StardewModdingAPI.Framework.ModLoading.Framework
                             }
                         }
 
-                        return new Tuple<bool, Exception>(anyRewritten, null);
+                        return Tuple.Create(anyRewritten, null as Exception);
                     }
                     catch (Exception e)
                     {
-                        return new Tuple<bool, Exception>(false, e.InnerException ?? e);
+                        return Tuple.Create(anyRewritten, e);
                     }
                 })
-                .Aggregate((tupleA, tupleB) => new Tuple<bool, Exception>(tupleA.Item1 | tupleB.Item1, tupleA.Item2 ?? tupleB.Item2)); // Aggregate result and exception
-            if (aggregateResult.Item2 != null)
-            {
-                throw aggregateResult.Item2; // rethrow inner Exception
-            }
-            return aggregateResult.Item1;
+                .Aggregate((a, b) => Tuple.Create(a.Item1 || b.Item1, a.Item2 ?? b.Item2));
+
+            bool rewritten = result.Item1;
+            Exception exception = result.Item2;
+            return exception == null
+                 ? rewritten
+                 : throw exception;
         }