Optimize bindings code generation via String Builder pooling

Source/Tools/Flax.Build/Bindings/BindingsGenerator.CSharp.cs

@@ -208,7 +208,7 @@ namespace Flax.Build.Bindings
                 }
                 else
                     throw new Exception("Cannot use array initializer as default value for type " + valueType);
-                var sb = new StringBuilder();
+                var sb = GetStringBuilder();
                 var items = new List<string>();
                 var braces = 0;
                 for (int i = 1; i < value.Length - 1; i++)
@@ -232,7 +232,9 @@ namespace Flax.Build.Bindings
                 for (int i = 0; i < items.Count; i++)
                     sb.Append(GenerateCSharpDefaultValueNativeToManaged(buildData, items[i], caller, itemType, attribute)).Append(',');
                 sb.Append('}');
-                return sb.ToString();
+                var result = sb.ToString();
+                PutStringBuilder(sb);
+                return result;
             }
 
             // Special case for value constructors
@@ -1979,7 +1981,7 @@ namespace Flax.Build.Bindings
 
         private static void GenerateCSharp(BuildData buildData, ModuleInfo moduleInfo, ref BindingsResult bindings)
         {
-            var contents = new StringBuilder();
+            var contents = GetStringBuilder();
             buildData.Modules.TryGetValue(moduleInfo.Module, out var moduleBuildInfo);
 
             // Header
@@ -2019,7 +2021,7 @@ namespace Flax.Build.Bindings
                 return;
 
             {
-                var header = new StringBuilder();
+                var header = GetStringBuilder();
 
                 // Using declarations
                 CSharpUsedNamespacesSorted.Clear();
@@ -2029,12 +2031,14 @@ namespace Flax.Build.Bindings
                     header.AppendLine($"using {CSharpUsedNamespacesSorted[i]};");
 
                 contents.Insert(headerPos, header.ToString());
+                PutStringBuilder(header);
             }
 
             // Save generated file
             contents.AppendLine();
             contents.AppendLine("#endif");
             Utilities.WriteFileIfChanged(bindings.GeneratedCSharpFilePath, contents.ToString());
+            PutStringBuilder(contents);
         }
 
         internal struct GuidInterop
@@ -2051,7 +2055,7 @@ namespace Flax.Build.Bindings
             if (binaryModule.All(x => !x.BuildCSharp))
                 return;
 
-            var contents = new StringBuilder();
+            var contents = GetStringBuilder();
             var binaryModuleName = binaryModule.Key;
             var project = Builder.GetModuleProject(binaryModule.First(), buildData);
 
@@ -2089,6 +2093,7 @@ namespace Flax.Build.Bindings
             contents.AppendLine("[assembly: DisableRuntimeMarshalling]");
 #endif
             Utilities.WriteFileIfChanged(dstFilePath, contents.ToString());
+            PutStringBuilder(contents);
         }
     }
 }

Source/Tools/Flax.Build/Bindings/BindingsGenerator.Cpp.cs

@@ -83,7 +83,7 @@ namespace Flax.Build.Bindings
 
         private static string GenerateCppWrapperNativeToVariantMethodName(TypeInfo typeInfo)
         {
-            var sb = new StringBuilder();
+            var sb = GetStringBuilder();
             sb.Append(typeInfo.Type.Replace("::", "_"));
             if (typeInfo.IsPtr)
                 sb.Append("Ptr");
@@ -96,7 +96,9 @@ namespace Flax.Build.Bindings
                         sb.Append("Ptr");
                 }
             }
-            return sb.ToString();
+            var result = sb.ToString();
+            PutStringBuilder(sb);
+            return result;
         }
 
         private static string GenerateCppWrapperNativeToManagedParam(BuildData buildData, StringBuilder contents, TypeInfo paramType, string paramName, ApiTypeInfo caller, bool isRef, out bool useLocalVar)
@@ -2548,7 +2550,7 @@ namespace Flax.Build.Bindings
 
         private static void GenerateCpp(BuildData buildData, ModuleInfo moduleInfo, ref BindingsResult bindings)
         {
-            var contents = new StringBuilder();
+            var contents = GetStringBuilder();
             CppUsedNonPodTypes.Clear();
             CppReferencesFiles.Clear();
             CppIncludeFiles.Clear();
@@ -2591,7 +2593,7 @@ namespace Flax.Build.Bindings
             GenerateCppModuleSource?.Invoke(buildData, moduleInfo, contents);
 
             {
-                var header = new StringBuilder();
+                var header = GetStringBuilder();
 
                 // Variant converting helper methods
                 foreach (var typeInfo in CppVariantToTypes)
@@ -2675,6 +2677,8 @@ namespace Flax.Build.Bindings
                     header.Append("    return result;").AppendLine();
                     header.Append('}').AppendLine();
                     header.AppendLine("}");
+
+                    PutStringBuilder(header);
                 }
 
                 // Non-POD types
@@ -2969,6 +2973,7 @@ namespace Flax.Build.Bindings
             contents.AppendLine("PRAGMA_ENABLE_DEPRECATION_WARNINGS");
 
             Utilities.WriteFileIfChanged(bindings.GeneratedCppFilePath, contents.ToString());
+            PutStringBuilder(contents);
         }
 
         private static void GenerateCpp(BuildData buildData, IGrouping<string, Module> binaryModule)
@@ -2978,7 +2983,7 @@ namespace Flax.Build.Bindings
                 return;
             var useCSharp = binaryModule.Any(x => x.BuildCSharp);
 
-            var contents = new StringBuilder();
+            var contents = GetStringBuilder();
             var binaryModuleName = binaryModule.Key;
             var binaryModuleNameUpper = binaryModuleName.ToUpperInvariant();
             var project = Builder.GetModuleProject(binaryModule.First(), buildData);
@@ -3031,6 +3036,7 @@ namespace Flax.Build.Bindings
             contents.AppendLine("}");
             GenerateCppBinaryModuleSource?.Invoke(buildData, binaryModule, contents);
             Utilities.WriteFileIfChanged(binaryModuleSourcePath, contents.ToString());
+            PutStringBuilder(contents);
         }
     }
 }

Source/Tools/Flax.Build/Bindings/BindingsGenerator.cs

@@ -4,6 +4,7 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using Flax.Build.NativeCpp;
@@ -59,6 +60,26 @@ namespace Flax.Build.Bindings
         public static event ParseFunctionParameterTagDelegate ParseFunctionParameterTag;
         public static ModuleInfo CurrentModule;
 
+        private static List<StringBuilder> _strignBuilderCache;
+
+        private static StringBuilder GetStringBuilder()
+        {
+            if (_strignBuilderCache == null || _strignBuilderCache.Count == 0)
+                return new StringBuilder();
+            var idx = _strignBuilderCache.Count - 1;
+            var result = _strignBuilderCache[idx];
+            _strignBuilderCache.RemoveAt(idx);
+            result.Clear();
+            return result;
+        }
+
+        private static void PutStringBuilder(StringBuilder value)
+        {
+            if (_strignBuilderCache == null)
+                _strignBuilderCache = new List<StringBuilder>();
+            _strignBuilderCache.Add(value);
+        }
+
         public static ModuleInfo ParseModule(BuildData buildData, Module module, BuildOptions moduleOptions = null)
         {
             if (buildData.ModulesInfo.TryGetValue(module, out var moduleInfo))