discovery fix

EpsonPrintService/PrinterDiscoveryBackgroundTask.cs

@@ -67,34 +67,45 @@ public class PrinterDiscoveryBackgroundTask
 
     private async Task DiscoverAndNotifyAsync()
     {
-        _printServer.EnterDiscoveryLock();
+        List<DiscoveredPrinter> printers;
+        HashSet<string> currentIps;
+        bool configChanged;
+
+        await _printServer.EnterDiscoveryLockAsync();
         try
         {
-            var printers = await _discoveryService.DiscoverPrintersAsync(_discoveryTimeout);
+            printers = await _discoveryService.DiscoverPrintersAsync(_discoveryTimeout);
+            currentIps = printers.Select(p => p.IPAddress).ToHashSet();
+            configChanged = HasConfigurationChanged(currentIps);
 
-            var currentIps = printers.Select(p => p.IPAddress).ToHashSet();
+            if (configChanged)
-
-            foreach (string currentIp in currentIps)
             {
-                _printServer.RegisterPrinter(currentIp);
-            }
-
-            if (HasConfigurationChanged(currentIps))
-            {
-                _logger.LogInformation("Discovered printer configuration changed: {Count} printer(s)", printers.Count);
                 _lastDiscoveredPrinterIps = currentIps;
                 _lastDiscoveredPrinters = printers;
-                await _receiver.OnPrintersDiscoveredAsync(printers.AsReadOnly());
             }
         }
         catch (Exception ex)
         {
             _logger.LogWarning(ex, "Failed to discover printers");
+            return; // Exit early on error
         }
         finally
         {
             _printServer.ExitDiscoveryLock();
         }
+
+        // Register printers AFTER releasing the lock
+        foreach (string currentIp in currentIps)
+        {
+            _logger.LogDebug("Registering discovered printer with IP: {IP}", currentIp);
+            _printServer.RegisterPrinter(currentIp);
+        }
+
+        if (configChanged)
+        {
+            _logger.LogInformation("Discovered printer configuration changed: {Count} printer(s)", printers.Count);
+            await _receiver.OnPrintersDiscoveredAsync(printers.AsReadOnly());
+        }
     }
 
     private bool HasConfigurationChanged(HashSet<string> currentIps)

EpsonPrintService/config.txt

@@ -1 +1 @@
-aHR0cDovL2xvY2FsaG9zdDo1MDAyOzY1YzM2MDYyZDM2ZTRjZmVlNmVjZjIyODtvWTVpcjViQi9pMXlSeFdpQ2FRTE1QdkFsS0dBaVVjNy8yK0IyczhXcUJzPQ==
+aHR0cHM6Ly9hcGkuZGV2Lmdhc3Ryb2phbWVzLmNoOzY4ODc1MjY2MTcxMjgxN2RlMjcxNTlmMjtGTEVEL1phQ2F5a0NrdEpCOHZzN1lqVFNyaStleGdKVWIva21WWk1lUHBNPQ==

EpsonTest/invoice.json

@@ -0,0 +1,6 @@
+{
+  "PrinterIp": "10.0.20.12",
+  "LogoUrl": "https://james-dev-public-images.s3.eu-central-1.amazonaws.com/01-21-26-15:26:16.jpeg",
+  "ReceiptType": 4,
+  "Content": "{\"CompanyName\":\"Gaumenfreuden\",\"Address1\":\"Orellistrasse 21\",\"Address2\":\"8044 Zurich\",\"Phone\":\"\\u002B380504371463\",\"ReceiptNumber\":null,\"DateTime\":\"2026-01-28T12:47:47.0874074Z\",\"Guests\":null,\"Items\":[{\"Quantity\":1,\"Description\":\"Beer light\",\"UnitPrice\":40,\"TotalPrice\":40,\"TaxCategory\":\"A\",\"SubItems\":null},{\"Quantity\":1,\"Description\":\"Premium Juice\",\"UnitPrice\":1.2,\"TotalPrice\":1.2,\"TaxCategory\":\"B\",\"SubItems\":null},{\"Quantity\":1,\"Description\":\"Beer light from Catalog\",\"UnitPrice\":20,\"TotalPrice\":20,\"TaxCategory\":\"A\",\"SubItems\":null},{\"Quantity\":1,\"Description\":\"Beer light from Catalog\",\"UnitPrice\":20,\"TotalPrice\":20,\"TaxCategory\":\"A\",\"SubItems\":null}],\"Total\":81.2,\"Currency\":\"CHF\",\"ThankYouMessage\":\"Thanks\",\"TableNumber\":\"HappyHoursDrinks\"}"
+}

Inspectron.Epson/Queue/PrintServer.cs

@@ -6,7 +6,9 @@ public class PrintServer
     private readonly IPrintService _printService;
     private readonly ILogger _logger;
     private readonly ConcurrentDictionary<string, PrinterQueue> _printerQueues;
-    private readonly ReaderWriterLockSlim _printDiscoveryLock = new();
+    private readonly SemaphoreSlim _printDiscoveryLock = new(1, 1);
+    private int _readerCount = 0;
+    private readonly object _readerCountLock = new();
 
     public PrintServer(IPrintService printService, ILogger logger)
     {
@@ -19,23 +21,58 @@ public class PrintServer
     /// <summary>
     /// Acquires a read lock for print operations. Multiple print operations can run concurrently.
     /// </summary>
-    public void EnterPrintLock() => _printDiscoveryLock.EnterReadLock();
+    public void EnterPrintLock()
+    {
+        _logger.LogDebug("Entering print lock");
+        lock (_readerCountLock)
+        {
+            _readerCount++;
+            if (_readerCount == 1)
+            {
+                _printDiscoveryLock.Wait();
+            }
+        }
+        _logger.LogDebug("Entered print lock");
+
+    }
 
     /// <summary>
     /// Releases the read lock after a print operation completes.
     /// </summary>
-    public void ExitPrintLock() => _printDiscoveryLock.ExitReadLock();
+    public void ExitPrintLock()
+    {
+        _logger.LogDebug("Exiting print lock");
+        lock (_readerCountLock)
+        {
+            _readerCount--;
+            if (_readerCount == 0)
+            {
+                _printDiscoveryLock.Release();
+            }
+        }
+        _logger.LogDebug("Exited print lock");
+    }
 
     /// <summary>
     /// Acquires a write lock for discovery operations. This blocks until all print operations complete
     /// and prevents new print operations from starting.
     /// </summary>
-    public void EnterDiscoveryLock() => _printDiscoveryLock.EnterWriteLock();
+    public async Task EnterDiscoveryLockAsync()
+    {
+        _logger.LogDebug("Entering discovery lock");
+        await _printDiscoveryLock.WaitAsync();
+        _logger.LogDebug("Entered discovery lock");
+    }
 
     /// <summary>
     /// Releases the write lock after discovery completes.
     /// </summary>
-    public void ExitDiscoveryLock() => _printDiscoveryLock.ExitWriteLock();
+    public void ExitDiscoveryLock()
+    {
+        _logger.LogDebug("Exiting discovery lock");
+        _printDiscoveryLock.Release();
+        _logger.LogDebug("Exited discovery lock");
+    }
 
     public void RegisterPrinter(string printerIp)
     {