Extract 'RethrowKeepingStackTrace' to a separate class

Related to #1399

Author: vbfox

src/Nest/ElasticClient.cs

@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
-using System.Reflection;
 using System.Threading.Tasks;
 using Elasticsearch.Net;
 using Elasticsearch.Net.Connection;
@@ -126,21 +125,6 @@ Func<D, D> selector
 			return this.DispatchAsync<D, Q, R, I>(descriptor, dispatch);
 		}
 
-		private static readonly Lazy<MethodInfo> preserveStackTraceMethodInfo = new Lazy<MethodInfo>(() => 
-			typeof(Exception).GetMethod("InternalPreserveStackTrace", BindingFlags.Instance | BindingFlags.NonPublic)
-		);
-
-		private static void RethrowKeepingStackTrace(Exception exception)
-		{
-			// In .Net 4.5 it would be simple : ExceptionDispatchInfo.Capture(exception).Throw();
-			// But as NEST target .Net 4.0 the old internal method must be used
-			if (preserveStackTraceMethodInfo.Value != null)
-			{
-				preserveStackTraceMethodInfo.Value.Invoke(exception, null);
-			}
-			throw exception;
-		}
-
 		private Task<I> DispatchAsync<D, Q, R, I>(
 			D descriptor
 			, Func<ElasticsearchPathInfo<Q>, D, Task<ElasticsearchResponse<R>>> dispatch
@@ -158,13 +142,13 @@ D descriptor
 					{
 						var mr = r.Exception.InnerException as MaxRetryException;
 						if (mr != null)
-							RethrowKeepingStackTrace(mr);
+							mr.RethrowKeepingStackTrace();
 
 						var ae = r.Exception.Flatten();
 						if (ae.InnerException != null)
-							RethrowKeepingStackTrace(ae.InnerException);
+							ae.InnerException.RethrowKeepingStackTrace();
 
-						RethrowKeepingStackTrace(ae);
+						ae.RethrowKeepingStackTrace();
 					}
 					return ResultsSelector<D, Q, R>(r.Result, descriptor);
 				});

src/Nest/Extensions/ExceptionExtensions.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Reflection;
+
+namespace Elasticsearch.Net
+{
+    internal static class ExceptionExtensions
+    {
+        private static readonly Lazy<MethodInfo> preserveStackTraceMethodInfo = new Lazy<MethodInfo>(() =>
+            typeof(Exception).GetMethod("InternalPreserveStackTrace", BindingFlags.Instance | BindingFlags.NonPublic)
+        );
+
+        public static void RethrowKeepingStackTrace(this Exception exception)
+        {
+            // In .Net 4.5 it would be simple : ExceptionDispatchInfo.Capture(exception).Throw();
+            // But as NEST target .Net 4.0 the old internal method must be used
+            if (preserveStackTraceMethodInfo.Value != null)
+            {
+                preserveStackTraceMethodInfo.Value.Invoke(exception, null);
+            }
+            throw exception;
+        }
+    }
+}

src/Nest/Nest.csproj

@@ -410,6 +410,7 @@
     <Compile Include="Exception\SnapshotException.cs" />
     <Compile Include="ExposedInternals\NestSerializer.cs" />
     <Compile Include="Enums\GeoDistance.cs" />
+    <Compile Include="Extensions\ExceptionExtensions.cs" />
     <Compile Include="Obsolete\Obsolete.cs" />
     <Compile Include="Resolvers\Converters\Aggregations\FiltersAggregatorConverter.cs" />
     <Compile Include="Resolvers\Converters\Aggregations\FilterAggregatorConverter.cs" />