From 1513b11d733149ad328e44017dde2069302fe2c5 Mon Sep 17 00:00:00 2001
From: James Newton-King <james@newtonking.com>
Date: Sun, 15 Jan 2017 09:45:24 +1300
Subject: [PATCH] -JsonTextReader new line async performance (#1172)

---
 Src/Newtonsoft.Json/JsonTextReader.Async.cs | 19 +++++++++++++++----
 Src/Newtonsoft.Json/JsonTextReader.cs       | 17 +++++++++++------
 2 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/Src/Newtonsoft.Json/JsonTextReader.Async.cs b/Src/Newtonsoft.Json/JsonTextReader.Async.cs
index 4eb340b0..8bae6915 100644
--- a/Src/Newtonsoft.Json/JsonTextReader.Async.cs
+++ b/Src/Newtonsoft.Json/JsonTextReader.Async.cs
@@ -490,16 +490,27 @@ namespace Newtonsoft.Json
             }
         }
 
-        private async Task ProcessCarriageReturnAsync(bool append, CancellationToken cancellationToken)
+        private Task ProcessCarriageReturnAsync(bool append, CancellationToken cancellationToken)
         {
             _charPos++;
 
-            if (await EnsureCharsAsync(1, append, cancellationToken).ConfigureAwait(false) && _chars[_charPos] == StringUtils.LineFeed)
+            Task<bool> task = EnsureCharsAsync(1, append, cancellationToken);
+            switch (task.Status)
             {
-                _charPos++;
+                case TaskStatus.RanToCompletion:
+                    SetNewLine(task.Result);
+                    return AsyncUtils.CompletedTask;
+                case TaskStatus.Canceled:
+                case TaskStatus.Faulted:
+                    return task;
             }
 
-            OnNewLine(_charPos);
+            return ProcessCarriageReturnAsync(task);
+        }
+
+        private async Task ProcessCarriageReturnAsync(Task<bool> task)
+        {
+            SetNewLine(await task.ConfigureAwait(false));
         }
 
         private async Task<char> ParseUnicodeAsync(CancellationToken cancellationToken)
diff --git a/Src/Newtonsoft.Json/JsonTextReader.cs b/Src/Newtonsoft.Json/JsonTextReader.cs
index 69041c7c..f33ce6d9 100644
--- a/Src/Newtonsoft.Json/JsonTextReader.cs
+++ b/Src/Newtonsoft.Json/JsonTextReader.cs
@@ -120,6 +120,16 @@ namespace Newtonsoft.Json
             }
         }
 
+        private void SetNewLine(bool hasNextChar)
+        {
+            if (hasNextChar && _chars[_charPos] == StringUtils.LineFeed)
+            {
+                _charPos++;
+            }
+
+            OnNewLine(_charPos);
+        }
+
         private void OnNewLine(int pos)
         {
             _lineNumber++;
@@ -1719,12 +1729,7 @@ namespace Newtonsoft.Json
         {
             _charPos++;
 
-            if (EnsureChars(1, append) && _chars[_charPos] == StringUtils.LineFeed)
-            {
-                _charPos++;
-            }
-
-            OnNewLine(_charPos);
+            SetNewLine(EnsureChars(1, append));
         }
 
         private void EatWhitespace()