Improvements in virtual device (#2496)

Author: josesimoes

targets/netcore/nanoFramework.nanoCLR.CLI/ExecuteCommandLineOptions.cs

@@ -79,6 +79,20 @@ public class ExecuteCommandLineOptions
             HelpText = "Parent process id to monitor - exit if the parent exits.")]
         public int? MonitorParentPid { get; set; }
 
+        [Option(
+            "waitfordebugger",
+            Required = false,
+            Default = false,
+            HelpText = "Option to wait for a debugger connection after nanoCLR is started.")]
+        public bool WaitForDebugger { get; set; }
+
+        [Option(
+            "loopafterexit",
+            Required = false,
+            Default = true,
+            HelpText = "Option to remain in loop waiting for a debugger connection after the program exits.")]
+        public bool EnterDebuggerLoopAfterExit { get; set; }
+
         /// <summary>
         /// Allowed values:
         /// q[uiet]

targets/netcore/nanoFramework.nanoCLR.CLI/ExecuteCommandProcessor.cs

@@ -60,8 +60,6 @@ public static int ProcessVerb(
                     // need to set debugger serial port to the _other_ port so it shows at the expected end
                     var internalSerialPort = $"COM{bridge.GetOtherPort(options.ExposedSerialPort)}";
 
-                    hostBuilder.WaitForDebugger = true;
-                    hostBuilder.EnterDebuggerLoopAfterExit = true;
                     hostBuilder.UseSerialPortWireProtocol(internalSerialPort);
 
                     // set flag
@@ -83,12 +81,6 @@ public static int ProcessVerb(
                 hostBuilder.TryResolve();
             }
 
-            if (options.ExposedSerialPort != null || options.ExposedTcpIpPort != null || options.ExposedNamedPipe != null)
-            {
-                hostBuilder.WaitForDebugger = true;
-                hostBuilder.EnterDebuggerLoopAfterExit = true;
-            }
-
             if (!internalSerialPortConfig
                 && options.ExposedSerialPort != null)
             {
@@ -110,6 +102,10 @@ public static int ProcessVerb(
                 hostBuilder.UsePortTrace();
             }
 
+            hostBuilder.WaitForDebugger = options.WaitForDebugger;
+            hostBuilder.EnterDebuggerLoopAfterExit = options.EnterDebuggerLoopAfterExit;
+
+
             if (options.MonitorParentPid != null)
             {
                 try

targets/netcore/nanoFramework.nanoCLR.CLI/README.md

@@ -116,6 +116,11 @@ This option tries to resolve cross-assembly references between the loaded assemb
 nanoclr run --resolve (--assemblies ...)
 ```
 
+### Options to control debugger connection
+
+There are two options that control how the nanoCLR execution interacts with a debugger. If it's intended that after a program terminates and exits the execution a debugger will be connecting, the option `--loopafterexit` should be included.
+In case it's expected that imediatly after nanoCLR is started,a debugger is to connect to it, the option `--waitfordebugger` should be included.
+
 ## Maintenance operations with the nanoCLR
 
 The nanoCLR it's, in fact, a wrapper to the nanoCLR instance that is distributed as DLL so it can be easily updated.

targets/netcore/nanoFramework.nanoCLR.Host/Port/NativeWireProtocolPort.cs

@@ -68,11 +68,14 @@ public void Open()
 
         public void Close()
         {
-            Status = PortStatus.Closed;
+            lock (_syncRoot)
+            {
+                Status = PortStatus.Closed;
 
-            Interop.nanoCLR.nanoCLR_WireProtocolClose();
-            Interop.nanoCLR.nanoCLR_SetWireProtocolReceiveCallback(null);
-            Interop.nanoCLR.nanoCLR_SetWireProtocolTransmitCallback(null);
+                Interop.nanoCLR.nanoCLR_WireProtocolClose();
+                Interop.nanoCLR.nanoCLR_SetWireProtocolReceiveCallback(null);
+                Interop.nanoCLR.nanoCLR_SetWireProtocolTransmitCallback(null);
+            }
         }
 
         private int WireProtocolTransmitCallback(byte[] data, int length)
@@ -85,13 +88,17 @@ private int WireProtocolTransmitCallback(byte[] data, int length)
             }
         }
 
+
         private int WireProtocolReceiveCallback(byte[] data, int length)
         {
             lock (_syncRoot)
             {
-                if (_receiveBuffer.Count == 0)
+                if (_receiveBuffer.Count == 0
+                    || Status == PortStatus.Closed)
                 {
-                    Monitor.Wait(_syncRoot);
+                    Thread.Yield();
+
+                    return 0;
                 }
 
                 var size = _receiveBuffer.Count < length ? _receiveBuffer.Count : length;
@@ -108,6 +115,7 @@ private void ProcessMessages()
             while (Status == PortStatus.Opened)
             {
                 Interop.nanoCLR.nanoCLR_WireProtocolProcess();
+                Thread.Yield();
             }
         }
     }

targets/netcore/nanoFramework.nanoCLR.Host/Port/Serial/SerialPort.cs

@@ -18,7 +18,7 @@ public SerialPort(string name, int baudRate = MaxBaud)
             _serialPort = new System.IO.Ports.SerialPort(name, baudRate);
         }
 
-        public int BytesAvailable => _serialPort.BytesToRead;
+        public int BytesAvailable => (_serialPort != null && _serialPort.IsOpen ? _serialPort.BytesToRead : 0);
 
         public byte[] ReceiveData() => _serialPort.ReadAllBytes();