Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Core/System/Linq/ParallelExecutionMode.cs

@@ -0,0 +1,39 @@
+// ==++==
+//
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+//
+// ParallelQueryExecutionMode.cs
+//
+// <OWNER>[....]</OWNER>
+//
+// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace System.Linq
+{
+
+    /// <summary>
+    /// The query execution mode is a hint that specifies how the system should handle
+    /// performance trade-offs when parallelizing queries.
+    /// </summary>
+    public enum ParallelExecutionMode
+    {
+        /// <summary>
+        /// By default, the system will use algorithms for queries
+        /// that are ripe for parallelism and will avoid algorithms with high 
+        /// overheads that will likely result in slow downs for parallel execution. 
+        /// </summary>
+        Default = 0,
+
+        /// <summary>
+        /// Parallelize the entire query, even if that means using high-overhead algorithms.
+        /// </summary>
+        ForceParallelism = 1,
+    }
+}