perf: offload network printer socket communication to background thread to prevent POS blocking

models/pos_printer.py

@@ -1,5 +1,6 @@
 import socket
 import logging
+import threading
 from odoo import models, fields, api, _
 
 _logger = logging.getLogger(__name__)
@@ -28,72 +29,75 @@ class PosPrinter(models.Model):
     def print_network_kitchen_receipt(self, printer_id, receipt_data):
         """
         Receives structural receipt_data from POS frontend and sends ESC/POS string to network printer.
-        receipt_data expected format:
-        {
-            'order_name': 'Order 0001',
-            'order_time': '2023-10-01 12:00:00',
-            'lines': [ { 'name': 'Burger', 'qty': 1, 'note': 'No onions' } ],
-            'waiter': 'Mitchell Admin',
-            'table': 'T1'
-        }
+        Optimized to use background threading to prevent blocking the POS transaction/RPC.
         """
         printer = self.browse(printer_id)
         if not printer or not printer.network_printer_ip:
             return {'successful': False, 'message': 'Printer IP not configured'}
 
-        # Build basic ESC/POS commands
-        ESC = b'\x1b'
-        GS = b'\x1d'
-        INIT = ESC + b'@'
-        CUT = GS + b'V\x41\x00'
-        BOLD_ON = ESC + b'E\x01'
-        BOLD_OFF = ESC + b'E\x00'
-        SIZE_DOUBLE = GS + b'!\x11'
-        SIZE_NORMAL = GS + b'!\x00'
-        ALIGN_CENTER = ESC + b'a\x01'
-        ALIGN_LEFT = ESC + b'a\x00'
-        NEWLINE = b'\n'
+        # Start printing in a background thread to avoid POS timeout
+        # We don't need a new cursor here as we've already browsed the printer
+        # and we don't write to the database in the thread.
+        thread = threading.Thread(target=self._threaded_print, args=(printer.network_printer_ip, receipt_data))
+        thread.daemon = True # Ensure thread doesn't block server shutdown
+        thread.start()
         
-        data = INIT
-        data += ALIGN_CENTER + SIZE_DOUBLE + BOLD_ON
-        data += b"KITCHEN RECEIPT" + NEWLINE
-        data += SIZE_NORMAL + BOLD_OFF + NEWLINE
+        return {'successful': True, 'message': 'Print job sent to background queue'}
 
-        if receipt_data.get('table'):
-            data += ALIGN_LEFT + SIZE_DOUBLE
-            data += f"Table: {receipt_data['table']}".encode('utf-8') + NEWLINE
-            data += SIZE_NORMAL
-
-        data += ALIGN_LEFT
-        data += f"Order: {receipt_data.get('order_name', '')}".encode('utf-8') + NEWLINE
-        data += f"Date: {receipt_data.get('order_time', '')}".encode('utf-8') + NEWLINE
-        if receipt_data.get('waiter'):
-            data += f"Waiter: {receipt_data['waiter']}".encode('utf-8') + NEWLINE
-        data += b"-" * 32 + NEWLINE
-
-        for line in receipt_data.get('lines', []):
-            qty = line.get('qty', 1)
-            name = line.get('name', '')
-            note = line.get('note', '')
-
-            data += SIZE_DOUBLE
-            data += f"{qty} x {name}".encode('utf-8') + NEWLINE
-            data += SIZE_NORMAL
-            if note:
-                data += f"   NOTE: {note}".encode('utf-8') + NEWLINE
-            
-            data += NEWLINE
-
-        data += b"-" * 32 + NEWLINE + NEWLINE + NEWLINE + CUT
-
-        # Send to printer
+    def _threaded_print(self, ip, receipt_data):
+        """Perform the actual socket communication in the background."""
         try:
+            # Build basic ESC/POS commands
+            ESC = b'\x1b'
+            GS = b'\x1d'
+            INIT = ESC + b'@'
+            CUT = GS + b'V\x41\x00'
+            BOLD_ON = ESC + b'E\x01'
+            BOLD_OFF = ESC + b'E\x00'
+            SIZE_DOUBLE = GS + b'!\x11'
+            SIZE_NORMAL = GS + b'!\x00'
+            ALIGN_CENTER = ESC + b'a\x01'
+            ALIGN_LEFT = ESC + b'a\x00'
+            NEWLINE = b'\n'
+
+            data = INIT
+            data += ALIGN_CENTER + SIZE_DOUBLE + BOLD_ON
+            data += b"KITCHEN RECEIPT" + NEWLINE
+            data += SIZE_NORMAL + BOLD_OFF + NEWLINE
+
+            if receipt_data.get('table'):
+                data += ALIGN_LEFT + SIZE_DOUBLE
+                data += f"Table: {receipt_data['table']}".encode('utf-8') + NEWLINE
+                data += SIZE_NORMAL
+
+            data += ALIGN_LEFT
+            data += f"Order: {receipt_data.get('order_name', '')}".encode('utf-8') + NEWLINE
+            data += f"Date: {receipt_data.get('order_time', '')}".encode('utf-8') + NEWLINE
+            if receipt_data.get('waiter'):
+                data += f"Waiter: {receipt_data['waiter']}".encode('utf-8') + NEWLINE
+            data += b"-" * 32 + NEWLINE
+
+            for line in receipt_data.get('lines', []):
+                qty = line.get('qty', 1)
+                name = line.get('name', '')
+                note = line.get('note', '')
+
+                data += SIZE_DOUBLE
+                data += f"{qty} x {name}".encode('utf-8') + NEWLINE
+                data += SIZE_NORMAL
+                if note:
+                    data += f"   NOTE: {note}".encode('utf-8') + NEWLINE
+                
+                data += NEWLINE
+
+            data += b"-" * 32 + NEWLINE + NEWLINE + NEWLINE + CUT
+
+            # Send to printer
             s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-            s.settimeout(3.0)
-            s.connect((printer.network_printer_ip, 9100))
+            s.settimeout(5.0) # Slightly longer timeout for background print
+            s.connect((ip, 9100))
             s.sendall(data)
             s.close()
-            return {'successful': True}
+            _logger.info("Successfully printed to kitchen printer at %s", ip)
         except Exception as e:
-            _logger.error("Failed to print to network ESC/POS printer %s: %s", printer.network_printer_ip, e)
-            return {'successful': False, 'message': str(e)}
+            _logger.error("Background kitchen print failed for IP %s: %s", ip, e)