Fix test

                                                 Method |           Mean |     StdDev |  Gen 0 | Allocated |
------------------------------------------------------- |--------------- |----------- |------- |---------- |
                            SerializeJsonStringToStream |    473.1403 ns |  2.3259 ns | 0.0343 |     183 B |
                         SerializeJsonString256ToStream |  1,594.0896 ns | 62.2681 ns | 0.0402 |     414 B |
                         SerializeJsonString512ToStream |  2,520.7552 ns |  7.5393 ns | 0.8331 |   2.93 kB |
                        SerializeJsonString4096ToStream | 14,798.8854 ns | 54.2097 ns | 1.0742 |   5.48 kB |

Author: xplicit

benchmarks/ServiceStack.Text.Benchmarks/JsonSerializationBenchmarks.cs

@@ -67,7 +67,7 @@ public class JsonSerializationBenchmarks
     {
         static ModelWithAllTypes allTypesModel = ModelWithAllTypes.Create(3);
         static ModelWithCommonTypes commonTypesModel = ModelWithCommonTypes.Create(3);
-        static MemoryStream stream = new MemoryStream(16384);
+        static MemoryStream stream = new MemoryStream(32768);
         const string serializedString = "this is the test string";
         readonly string serializedString256 = new string('t', 256);
         readonly string serializedString512 = new string('t', 512);

src/ServiceStack.Text/DirectStreamWriter.cs

@@ -11,7 +11,8 @@ public class DirectStreamWriter : TextWriter
 
         private Stream stream;
         private StreamWriter writer = null;
-        private char[] curChar = new char[1];
+        private byte[] curChar = new byte[1];
+        private bool needFlush = false;
 
         private Encoding encoding;
         public override Encoding Encoding => encoding;
@@ -26,25 +27,44 @@ public override void Write(string s)
         {
             if (s.Length <= optimizedBufferLength)
             {
+                if (needFlush) 
+                {
+                    writer.Flush();
+                    needFlush = false;
+                }
+
                 byte[] buffer = Encoding.GetBytes(s);
                 stream.Write(buffer, 0, buffer.Length);
-            } 
-            else 
+            } else 
             {
                 if (writer == null)
                     writer = new StreamWriter(stream, Encoding, s.Length < maxBufferLength ? s.Length : maxBufferLength);
 
                 writer.Write(s);
-                writer.Flush();
+                needFlush = true;
             }
         }
 
         public override void Write(char c)
         {
-            curChar[0] = c;
+            if ((int)c < 128)
+            {
+                if (needFlush)
+                {
+                    writer.Flush();
+                    needFlush = false;
+                }
 
-            byte[] buffer = Encoding.GetBytes(curChar);
-            stream.Write(buffer, 0, buffer.Length);
+                curChar[0] = (byte)c;
+                stream.Write(curChar, 0, 1);
+            } else
+            {
+                if (writer == null)
+                    writer = new StreamWriter(stream, Encoding, optimizedBufferLength);
+                
+                writer.Write(c);
+                needFlush = true;
+            }
         }
 
         public override void Flush()

tests/ServiceStack.Text.Tests/JsonObjectTests.cs

@@ -66,6 +66,30 @@ public void Does_encode_unicode()
             }
         }
 
+        [Test]
+        public void Does_encode_large_strings()
+        {
+            char[] testChars = new char[32769];
+            for (int i = 0; i < testChars.Length; i++)
+                testChars[i] = (char)i;
+
+            string test = new string(testChars);
+
+            var obj = new { test };
+            using (var mem = new System.IO.MemoryStream())
+            {
+                ServiceStack.Text.JsonSerializer.SerializeToStream(obj, obj.GetType(), mem);
+
+                var encoded = System.Text.Encoding.UTF8.GetString(mem.ToArray());
+
+                var copy1 = JsonObject.Parse(encoded);
+
+                Assert.That(test, Is.EqualTo(copy1["test"]));
+
+                System.Diagnostics.Debug.WriteLine(copy1["test"]);
+            }
+        }
+
         [Test]
         public void Can_parse_Twitter_response()
         {