In JavaScriptEngineSwitcher.ChakraCore optimized a memory usage by using unsafe code

Author: Taritsyn

src/JavaScriptEngineSwitcher.ChakraCore/ChakraCorePrecompiledScript.cs

@@ -91,11 +91,10 @@ private bool LoadScriptSourceCode(JsSourceContext sourceContext,
 			parseAttributes = ParseAttributes;
 			Encoding encoding = parseAttributes.HasFlag(JsParseScriptAttributes.ArrayBufferIsUtf16Encoded) ?
 				Encoding.Unicode : Encoding.UTF8;
-			byte[] bytes = encoding.GetBytes(Code);
 
 			try
 			{
-				value = JsValue.CreateExternalArrayBuffer(bytes);
+				value = JsValue.CreateExternalArrayBuffer(Code, encoding);
 				result = true;
 			}
 			catch (OriginalException)

src/JavaScriptEngineSwitcher.ChakraCore/Helpers/EncodingHelpers.cs

@@ -0,0 +1,53 @@
+#if NET471 || NETSTANDARD
+using System;
+using System.Runtime.InteropServices;
+#endif
+using System.Text;
+
+namespace JavaScriptEngineSwitcher.ChakraCore.Helpers
+{
+	/// <summary>
+	/// Encoding helpers
+	/// </summary>
+	internal static class EncodingHelpers
+	{
+#if NET471 || NETSTANDARD
+		public static unsafe string UnicodeToUtf8(string value, out int byteCount)
+#else
+		public static string UnicodeToUtf8(string value, out int byteCount)
+#endif
+		{
+			if (string.IsNullOrEmpty(value))
+			{
+				byteCount = 0;
+				return value;
+			}
+
+			string result;
+#if NET471 || NETSTANDARD
+			byteCount = Encoding.UTF8.GetByteCount(value);
+			IntPtr bufferPtr = Marshal.AllocHGlobal(byteCount);
+
+			try
+			{
+				fixed (char* pValue = value)
+				{
+					Encoding.UTF8.GetBytes(pValue, value.Length, (byte*)bufferPtr, byteCount);
+				}
+
+				result = Encoding.GetEncoding(0).GetString((byte*)bufferPtr, byteCount);
+			}
+			finally
+			{
+				Marshal.FreeHGlobal(bufferPtr);
+			}
+#else
+			byte[] bytes = Encoding.UTF8.GetBytes(value);
+			byteCount = bytes.Length;
+			result = Encoding.GetEncoding(0).GetString(bytes);
+#endif
+
+			return result;
+		}
+	}
+}

src/JavaScriptEngineSwitcher.ChakraCore/JavaScriptEngineSwitcher.ChakraCore.csproj

@@ -7,6 +7,7 @@
 		<TargetFrameworks>net40-client;net45;net471;netstandard1.3;netstandard2.0</TargetFrameworks>
 		<NetStandardImplicitPackageVersion Condition=" '$(TargetFramework)' == 'netstandard1.3' ">1.6.0</NetStandardImplicitPackageVersion>
 		<OutputType>Library</OutputType>
+		<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
 		<TreatWarningsAsErrors>true</TreatWarningsAsErrors>
 		<NoWarn>$(NoWarn);CS1591</NoWarn>
 		<GenerateDocumentationFile>true</GenerateDocumentationFile>
@@ -22,7 +23,8 @@ This package does not contain the native implementations of ChakraCore. Therefor
  * JavaScriptEngineSwitcher.ChakraCore.Native.osx-x64</Description>
 		<PackageIconUrl>https://raw.githubusercontent.com/Taritsyn/JavaScriptEngineSwitcher/master/Icons/JavaScriptEngineSwitcher_ChakraCore_Logo128x128.png</PackageIconUrl>
 		<PackageTags>JavaScriptEngineSwitcher;JavaScript;ECMAScript;ChakraCore</PackageTags>
-		<PackageReleaseNotes>No longer used the old ChakraCore API for Windows (Internet Explorer-like API).</PackageReleaseNotes>
+		<PackageReleaseNotes>1. No longer used the old ChakraCore API for Windows (Internet Explorer-like API);
+2. Optimized a memory usage.</PackageReleaseNotes>
 	</PropertyGroup>
 
 	<Import Project="../../build/common.props" />

src/JavaScriptEngineSwitcher.ChakraCore/JsRt/JsContext.cs

@@ -1,8 +1,6 @@
 using System;
-using System.Text;
-#if NET45 || NET471 || NETSTANDARD
 using System.Runtime.InteropServices;
-#endif
+using System.Text;
 #if NET40
 
 using JavaScriptEngineSwitcher.Core.Polyfills.System.Runtime.InteropServices;
@@ -366,8 +364,7 @@ private static JsValue CreateExternalArrayBufferFromScriptCode(string script,
 				encoding = Encoding.UTF8;
 			}
 
-			byte[] scriptBytes = encoding.GetBytes(script);
-			JsValue scriptValue = JsValue.CreateExternalArrayBuffer(scriptBytes);
+			JsValue scriptValue = JsValue.CreateExternalArrayBuffer(script, encoding);
 
 			return scriptValue;
 		}

src/JavaScriptEngineSwitcher.ChakraCore/JsRt/JsPropertyId.cs

@@ -8,6 +8,8 @@
 using JavaScriptEngineSwitcher.Core.Polyfills.System.Runtime.InteropServices;
 #endif
 
+using JavaScriptEngineSwitcher.ChakraCore.Helpers;
+
 namespace JavaScriptEngineSwitcher.ChakraCore.JsRt
 {
 	/// <summary>
@@ -93,16 +95,14 @@ public static JsPropertyId FromString(string name)
 			string processedName;
 			int byteCount;
 
-			if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows) && !string.IsNullOrEmpty(name))
+			if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
 			{
-				byte[] bytes = Encoding.UTF8.GetBytes(name);
-				processedName = Encoding.GetEncoding(0).GetString(bytes);
-				byteCount = bytes.Length;
+				processedName = EncodingHelpers.UnicodeToUtf8(name, out byteCount);
 			}
 			else
 			{
 				processedName = name;
-				byteCount = Encoding.UTF8.GetByteCount(name);
+				byteCount = Encoding.UTF8.GetByteCount(processedName);
 			}
 
 			JsPropertyId id;

src/JavaScriptEngineSwitcher.ChakraCore/JsRt/JsValue.cs

@@ -474,6 +474,47 @@ public static JsValue CreateExternalArrayBuffer(byte[] buffer)
 			return reference;
 		}
 
+		/// <summary>
+		/// Creates a Javascript <c>ArrayBuffer</c> object to access external memory
+		/// </summary>
+		/// <remarks>Requires an active script context.</remarks>
+		/// <param name="value">String value</param>
+		/// <param name="encoding">Character encoding</param>
+		/// <returns>The new <c>ArrayBuffer</c> object</returns>
+		public static unsafe JsValue CreateExternalArrayBuffer(string value, Encoding encoding)
+		{
+			int bufferLength;
+			IntPtr bufferPtr;
+			JsObjectFinalizeCallback finalizeCallback;
+
+			if (value != null)
+			{
+				bufferLength = encoding.GetByteCount(value);
+				bufferPtr = Marshal.AllocHGlobal(bufferLength);
+
+				fixed (char* pScript = value)
+				{
+					encoding.GetBytes(pScript, value.Length, (byte*)bufferPtr, bufferLength);
+				}
+
+				finalizeCallback = DefaultExternalBufferFinalizeCallback.Instance;
+			}
+			else
+			{
+				bufferLength = 0;
+				bufferPtr = IntPtr.Zero;
+				finalizeCallback = null;
+			}
+
+			JsValue reference;
+			JsErrorCode errorCode = NativeMethods.JsCreateExternalArrayBuffer(bufferPtr, (uint)bufferLength,
+				finalizeCallback, bufferPtr, out reference);
+			JsErrorHelpers.ThrowIfError(errorCode);
+
+			return reference;
+		}
+
+
 		/// <summary>
 		/// Creates a new JavaScript error object
 		/// </summary>

src/JavaScriptEngineSwitcher.ChakraCore/readme.txt

@@ -30,7 +30,9 @@
    =============
    RELEASE NOTES
    =============
-   No longer used the old ChakraCore API for Windows (Internet Explorer-like API).
+   1. No longer used the old ChakraCore API for Windows (Internet Explorer-like
+      API);
+   2. Optimized a memory usage.
 
    =============
    DOCUMENTATION