From 83ee7baed689cced8c28e4d4c4631132cad86dbd Mon Sep 17 00:00:00 2001
From: marcbarry <marc.barry@gmail.com>
Date: Tue, 14 Mar 2017 21:35:12 +0000
Subject: [PATCH] workaround for cpu spin when NamedPipeClientStream.Connect()
 is called without a timeout

---
 NamedPipeWrapper/NamedPipeClient.cs      | 31 +++++++++++++++++++++++-
 NamedPipeWrapper/NamedPipeWrapper.csproj |  1 +
 NamedPipeWrapper/Native/Kernel32.cs      | 17 +++++++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 NamedPipeWrapper/Native/Kernel32.cs

diff --git a/NamedPipeWrapper/NamedPipeClient.cs b/NamedPipeWrapper/NamedPipeClient.cs
index a1132c5..ed23855 100644
--- a/NamedPipeWrapper/NamedPipeClient.cs
+++ b/NamedPipeWrapper/NamedPipeClient.cs
@@ -1,10 +1,12 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.IO.Pipes;
 using System.Linq;
 using System.Text;
 using System.Threading;
 using NamedPipeWrapper.IO;
+using NamedPipeWrapper.Native;
 using NamedPipeWrapper.Threading;
 
 namespace NamedPipeWrapper
@@ -219,7 +221,7 @@ public static PipeStreamWrapper<TRead, TWrite> Connect<TRead, TWrite>(string pip
         public static NamedPipeClientStream CreateAndConnectPipe(string pipeName, string serverName)
         {
             var pipe = CreatePipe(pipeName, serverName);
-            pipe.Connect();
+            ConnectWithRetry(pipe, Path.GetFullPath($@"\\{serverName}\pipe\{pipeName}"));
             return pipe;
         }
 
@@ -227,5 +229,32 @@ private static NamedPipeClientStream CreatePipe(string pipeName,string serverNam
         {
             return new NamedPipeClientStream(serverName, pipeName, PipeDirection.InOut, PipeOptions.Asynchronous | PipeOptions.WriteThrough);
         }
+
+        private static void ConnectWithRetry(NamedPipeClientStream pipe, string fullPath)
+        {
+            var connected = false;
+            var resetEvent = new ManualResetEvent(false);
+
+            while (!connected)
+            {
+                if (!Kernel32.WaitNamedPipe(fullPath, 0xffffffff))
+                {
+                    resetEvent.WaitOne(100); // prevent cpu spin
+                }
+                else
+                {
+                    try
+                    {
+                        // NamedPipeClientStream.Connect() defaults to a timeout value of -1, which blocks and spins the CPU, provide a sensible timeout value for Connect().
+                        pipe.Connect(15000);
+                        connected = true;
+                    }
+                    catch (TimeoutException)
+                    {
+                        connected = false;
+                    }
+                }
+            }
+        }
     }
 }
diff --git a/NamedPipeWrapper/NamedPipeWrapper.csproj b/NamedPipeWrapper/NamedPipeWrapper.csproj
index 90ec8e9..b86e053 100644
--- a/NamedPipeWrapper/NamedPipeWrapper.csproj
+++ b/NamedPipeWrapper/NamedPipeWrapper.csproj
@@ -45,6 +45,7 @@
     <Compile Include="IO\PipeStreamReader.cs" />
     <Compile Include="IO\PipeStreamWrapper.cs" />
     <Compile Include="IO\PipeStreamWriter.cs" />
+    <Compile Include="Native\Kernel32.cs" />
     <Compile Include="PipeExceptionEventHandler.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="NamedPipeServer.cs" />
diff --git a/NamedPipeWrapper/Native/Kernel32.cs b/NamedPipeWrapper/Native/Kernel32.cs
new file mode 100644
index 0000000..8092831
--- /dev/null
+++ b/NamedPipeWrapper/Native/Kernel32.cs
@@ -0,0 +1,17 @@
+using System.Runtime.InteropServices;
+
+namespace NamedPipeWrapper.Native
+{
+    internal sealed class Kernel32
+    {
+        /// <summary>
+        /// Waits until either a time-out interval elapses or an instance of the specified named pipe is available for connection
+        /// </summary>
+        /// <param name="lpNamedPipeName">The name of the named pipe. The string must include the name of the computer on which the server process is executing.</param>
+        /// <param name="nTimeOut">If no instances of the specified named pipe exist, the WaitNamedPipe function returns immediately, regardless of the time-out value.</param>
+        /// <returns></returns>
+        [return: MarshalAs(UnmanagedType.Bool)]
+        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
+        internal static extern bool WaitNamedPipe(string lpNamedPipeName, uint nTimeOut);
+    }
+}
\ No newline at end of file