From 2ed285ee75a266625a8b1ec394daab9ff1c3d5cc Mon Sep 17 00:00:00 2001
From: Morten Nielsen <mn@iter.dk>
Date: Tue, 19 Nov 2024 20:33:29 -0800
Subject: [PATCH] Adds disconnection handling

Fixes #114
---
 src/NmeaParser/NmeaDevice.cs                | 27 ++++++++++++++++++++-
 src/SampleApp.WinDesktop/MainWindow.xaml.cs |  8 +++++-
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/NmeaParser/NmeaDevice.cs b/src/NmeaParser/NmeaDevice.cs
index 691168c..ccb084f 100644
--- a/src/NmeaParser/NmeaDevice.cs
+++ b/src/NmeaParser/NmeaDevice.cs
@@ -70,6 +70,7 @@ namespace NmeaParser
             System.Diagnostics.Debug.WriteLine("Starting parser...");
             m_ParserTask = Task.Run(async () =>
             {
+                int failcounter = 0;
                 byte[] buffer = new byte[1024];
                 while (!token.IsCancellationRequested)
                 {
@@ -77,8 +78,17 @@ namespace NmeaParser
                     try
                     {
                         readCount = await ReadAsync(buffer, 0, 1024, token).ConfigureAwait(false);
+                        failcounter = 0;
+                    }
+                    catch(System.Exception ex)
+                    {
+                        failcounter++;
+                        if (failcounter > 10)
+                        {
+                            OnDisconnecting(ex);
+                            break;
+                        }
                     }
-                    catch { }
                     if (token.IsCancellationRequested)
                         break;
                     if (readCount > 0)
@@ -90,6 +100,16 @@ namespace NmeaParser
             });
         }
 
+        private async void OnDisconnecting(Exception ex)
+        {
+            try
+            {
+                await this.CloseAsync().ConfigureAwait(false);
+            }
+            catch { }
+            DeviceDisconnected.Invoke(this, ex);
+        }
+
         /// <summary>
         /// Performs a read operation of the stream
         /// </summary>
@@ -219,6 +239,11 @@ namespace NmeaParser
         /// </summary>
         public event EventHandler<NmeaMessageReceivedEventArgs>? MessageReceived;
 
+        /// <summary>
+        /// Raised when a device raises the same error multiple times and can't recover.
+        /// </summary>
+        public event EventHandler<Exception> DeviceDisconnected;
+
         /// <summary>
         /// Releases unmanaged and - optionally - managed resources.
         /// </summary>
diff --git a/src/SampleApp.WinDesktop/MainWindow.xaml.cs b/src/SampleApp.WinDesktop/MainWindow.xaml.cs
index 435b788..639674f 100644
--- a/src/SampleApp.WinDesktop/MainWindow.xaml.cs
+++ b/src/SampleApp.WinDesktop/MainWindow.xaml.cs
@@ -84,6 +84,7 @@ namespace SampleApp.WinDesktop
             if (currentDevice != null)
             {
                 currentDevice.MessageReceived -= device_MessageReceived;
+                currentDevice.DeviceDisconnected -= device_DeviceDisconnected;
                 if (currentDevice.IsOpen)
                     await currentDevice.CloseAsync();
                 currentDevice.Dispose();
@@ -110,7 +111,7 @@ namespace SampleApp.WinDesktop
                 MessagePanel.Children.Remove(child);
             }
             currentDevice.MessageReceived += device_MessageReceived;
-
+            currentDevice.DeviceDisconnected += device_DeviceDisconnected;
             if (device is NmeaParser.NmeaFileDevice)
                 currentDeviceInfo.Text = string.Format("NmeaFileDevice( file={0} )", ((NmeaParser.NmeaFileDevice)device).FileName);
             else if (device is NmeaParser.SerialPortDevice)
@@ -130,6 +131,11 @@ namespace SampleApp.WinDesktop
             view3d.GnssMonitor = monitor;
         }
 
+        private void device_DeviceDisconnected(object sender, Exception e)
+        {
+            MessageBox.Show("Device disconnected: " + e.Message);
+        }
+
         private void Monitor_LocationChanged(object sender, EventArgs e)
         {
             var mon = sender as GnssMonitor;