Redesign message I/O to use byte streams

This change redesigns the existing MessageReader and MessageWriter classes
to read/write messages using Streams instead of TextReader/TextWriter
classes.  This makes the host process compatible with VS Code's latest
debugger client so that messages sent from it can be read correctly.  It
also sets us up for being able to communicate through other types of
streams such as sockets.

Author: daviwil

src/PowerShellEditorServices.Host/MessageLoop.cs

@@ -12,6 +12,7 @@
 using Microsoft.PowerShell.EditorServices.Transport.Stdio.Response;
 using Nito.AsyncEx;
 using System;
+using System.IO;
 using System.Management.Automation;
 using System.Reflection;
 using System.Text;
@@ -24,6 +25,8 @@ public class MessageLoop : IHost
     {
         #region Private Fields
 
+        private Stream inputStream;
+        private Stream outputStream;
         private IConsoleHost consoleHost;
         private EditorSession editorSession;
         private MessageReader messageReader;
@@ -75,17 +78,19 @@ async Task ListenForMessages()
             MessageTypeResolver messageTypeResolver = new MessageTypeResolver();
             messageTypeResolver.ScanForMessageTypes(typeof(StartedEvent).Assembly);
 
+            // Open the standard input/output streams
+            this.inputStream = System.Console.OpenStandardInput();
+            this.outputStream = System.Console.OpenStandardOutput();
+
             // Set up the reader and writer
             this.messageReader = 
                 new MessageReader(
-                    System.Console.In,
-                    MessageFormat.WithContentLength,
+                    this.inputStream,
                     messageTypeResolver);
 
             this.messageWriter = 
                 new MessageWriter(
-                    System.Console.Out, 
-                    MessageFormat.WithContentLength,
+                    this.outputStream,
                     messageTypeResolver);
 
             // Set up the console host which will send events
@@ -102,7 +107,7 @@ async Task ListenForMessages()
             this.editorSession.DebugService.DebuggerStopped += DebugService_DebuggerStopped;
 
             // Send a "started" event
-            this.messageWriter.WriteMessage(
+            await this.messageWriter.WriteMessage(
                 new StartedEvent());
 
             // Run the message loop
@@ -120,7 +125,7 @@ async Task ListenForMessages()
                 {
                     // Write an error response
                     this.messageWriter.WriteMessage(
-                        MessageErrorResponse.CreateParseErrorResponse(e));
+                        MessageErrorResponse.CreateParseErrorResponse(e)).Wait();
 
                     // Continue the loop
                     continue;
@@ -141,7 +146,7 @@ await messageProcessor.ProcessMessage(
                     if (newMessage != null)
                     {
                         // Return an error response to keep the client moving
-                        this.messageWriter.WriteMessage(
+                        await this.messageWriter.WriteMessage(
                             MessageErrorResponse.CreateUnhandledMessageResponse(
                                 newMessage));
                     }
@@ -154,9 +159,9 @@ await messageProcessor.ProcessMessage(
             }
         }
 
-        void DebugService_DebuggerStopped(object sender, DebuggerStopEventArgs e)
+        async void DebugService_DebuggerStopped(object sender, DebuggerStopEventArgs e)
         {
-            this.messageWriter.WriteMessage(
+            await this.messageWriter.WriteMessage(
                 new StoppedEvent
                 {
                     Body = new StoppedEventBody
@@ -177,11 +182,11 @@ void PowerShellSession_BreakpointUpdated(object sender, BreakpointUpdatedEventAr
         {
         }
 
-        void PowerShellSession_OutputWritten(object sender, OutputWrittenEventArgs e)
+        async void PowerShellSession_OutputWritten(object sender, OutputWrittenEventArgs e)
         {
             // TODO: change this to use the OutputEvent!
 
-            this.messageWriter.WriteMessage(
+            await this.messageWriter.WriteMessage(
                 new ReplWriteOutputEvent
                 {
                     Body = new ReplWriteOutputEventBody

src/PowerShellEditorServices.Host/Program.cs

@@ -27,6 +27,8 @@ static void Main(string[] args)
                             "/waitForDebugger",
                             StringComparison.InvariantCultureIgnoreCase));
 
+            waitForDebugger = true;
+
             // Should we wait for the debugger before starting?
             if (waitForDebugger)
             {

src/PowerShellEditorServices.Transport.Stdio/Constants.cs

@@ -16,7 +16,7 @@ namespace Microsoft.PowerShell.EditorServices.Transport.Stdio
 {
     public static class Constants
     {
-        public const string ContentLengthString = "Content-Length: ";
+        public const string ContentLengthFormatString = "Content-Length: {0}\r\n\r\n";
         public static readonly JsonSerializerSettings JsonSerializerSettings;
 
         static Constants()