From d948ba4135ce2997d362ba31114e98c1da9362d8 Mon Sep 17 00:00:00 2001
From: Pilzinsel64 <pascal.schedel@dr-schneider.com>
Date: Wed, 22 Jan 2025 15:20:39 +0100
Subject: [PATCH] auto-restart on fatal http error

---
 Pilz.Net/Api/ApiServer.cs | 52 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 3 deletions(-)

diff --git a/Pilz.Net/Api/ApiServer.cs b/Pilz.Net/Api/ApiServer.cs
index 55446c7..3078a3d 100644
--- a/Pilz.Net/Api/ApiServer.cs
+++ b/Pilz.Net/Api/ApiServer.cs
@@ -13,7 +13,9 @@ public class ApiServer(string apiUrl) : IApiServer
 {
     protected readonly List<PrivateMessageHandler> handlers = [];
     protected readonly Dictionary<Type, IApiMessageSerializer> serializers = [];
-    protected readonly HttpListener httpListener = new();
+    protected HttpListener httpListener = new();
+    protected int restartAttempts = 0;
+    protected DateTime lastRestartAttempt;
 
     public event OnCheckAuthenticationEventHandler? OnCheckAuthentication;
     public event OnCheckContextEventHandler? OnCheckContext;
@@ -37,18 +39,48 @@ public class ApiServer(string apiUrl) : IApiServer
 
     public bool AllowMultipleRequests { get; set; }
 
+    public int StopDelay { get; set; } = 5000;
+
+    public int AutoRestartOnError { get; set; } = 5000;
+
+    public int MaxAutoRestartsPerMinute { get; set; } = 10;
+
     public virtual void Start()
     {
-        Log.Info("Start listening");
+        Log.Info("Starting listener");
         httpListener.Prefixes.Add(ApiUrl + "/");
         httpListener.Start();
+        Log.Info("Started listener");
         Receive();
     }
 
     public virtual void Stop()
     {
+        Log.Info("Stopping listener");
         httpListener.Stop();
-        Log.Info("Stopped listening");
+        Thread.Sleep(StopDelay);
+        httpListener.Close();
+        Log.Info("Stopped listener");
+    }
+
+    public virtual bool Restart()
+    {
+        if (restartAttempts > MaxAutoRestartsPerMinute)
+            return false;
+
+        var now = DateTime.Now;
+        if (now - lastRestartAttempt > TimeSpan.FromMinutes(1))
+            lastRestartAttempt = now;
+
+        restartAttempts += 1;
+
+        Log.Info("Restarting listener");
+        Stop();
+        httpListener = new();
+        Start();
+        Log.Info("Restarted listener");
+
+        return true;
     }
 
     public virtual void RegisterHandler<T>(T instance) where T : class
@@ -130,6 +162,18 @@ public class ApiServer(string apiUrl) : IApiServer
         {
             context = httpListener.EndGetContext(result);
         }
+        catch (HttpListenerException ex)
+        {
+            if (ex.ErrorCode == 995 || ex.ErrorCode == 64)
+            {
+                Log.Fatal($"Fatal http error retriving context with code {ex.ErrorCode}", ex);
+                if (Restart()) // Try restart the server and skip this context
+                    return;
+            }
+            else
+                Log.Error($"Http error retriving context with code {ex.ErrorCode}", ex);
+            context = null;
+        }
         catch (Exception ex)
         {
             Log.Error("Error retriving context", ex);
@@ -251,11 +295,13 @@ public class ApiServer(string apiUrl) : IApiServer
             context.Response.ContentType = "application/json";
             using StreamWriter output = new(context.Response.OutputStream);
             output.Write(resultJson);
+            output.Flush();
         }
         else if (result.ResultContent is byte[] resultBytes)
         {
             Log.Info("Sending raw bytes response for " + context.Request.RawUrl);
             context.Response.OutputStream.Write(resultBytes, 0, resultBytes.Length);
+            context.Response.OutputStream.Flush();
         }
 
         Log.Debug("Finish response");