Make server proxy notif port listing async (#301)

Author: pantherman594

src/jupyter-common/extension-builder/extension/server-proxy-notif/server_proxy_notif/handlers.py

@@ -1,11 +1,15 @@
 import json
-import subprocess
+import getpass
 import re
+import subprocess
 import logging
-from typing import Set, Dict, List
+from typing import Set, Optional, Tuple
 from jupyter_server.base.handlers import APIHandler
 from jupyter_server.utils import url_path_join
 import tornado
+from tornado.process import Subprocess
+from tornado.gen import with_timeout
+from datetime import timedelta
 
 logger = logging.getLogger(__name__)
 
@@ -14,8 +18,8 @@ class PortMonitorHandler(APIHandler):
     """Handler for monitoring listening ports"""
 
     @tornado.web.authenticated
-    def get(self):
-        """Get currently listening ports"""
+    async def get(self):
+        """Get currently listening ports asynchronously"""
         try:
             # Check if jupyter-server-proxy is installed
             try:
@@ -30,7 +34,7 @@ def get(self):
                 return
 
             logger.info('Port monitor API called')
-            ports, warning = self._get_listening_ports()
+            ports, warning = await self._get_listening_ports()
             logger.info(f'Found {len(ports)} listening ports: {sorted(ports)}')
             response = {'ports': list(ports)}
             if warning:
@@ -43,48 +47,61 @@ def get(self):
                 'error': str(e)
             }))
 
-    def _get_listening_ports(self) -> tuple[Set[int], str]:
-        """Get list of listening ports using lsof (user-owned only)
+    async def _get_listening_ports(self) -> Tuple[Set[int], Optional[str]]:
+        """Get list of listening ports using lsof asynchronously (user-owned only)
 
         Returns:
             tuple: (set of port numbers, warning message or None)
         """
         ports = set()
         warning = None
 
+        # Get current username
+        username = getpass.getuser()
+
+        # Use lsof to find listening TCP ports owned by current user
+        # -a means AND (combine conditions)
+        # -u $USER shows only current user's processes
+        # -i TCP -s TCP:LISTEN shows only listening TCP sockets
+        # -P prevents port name resolution (shows numbers)
+        # -n prevents hostname resolution (faster)
         try:
-            # Use lsof to find listening TCP ports owned by current user
-            # -a means AND (combine conditions)
-            # -u $USER shows only current user's processes
-            # -i TCP -s TCP:LISTEN shows only listening TCP sockets
-            # -P prevents port name resolution (shows numbers)
-            # -n prevents hostname resolution (faster)
-            result = subprocess.run(
-                ['lsof', '-a', '-u', str(subprocess.getoutput('whoami')), '-i', 'TCP', '-s', 'TCP:LISTEN', '-P', '-n'],
-                capture_output=True,
-                text=True,
-                timeout=5
+            process = Subprocess(
+                ['lsof', '-a', '-u', username, '-i', 'TCP', '-s', 'TCP:LISTEN', '-P', '-n'],
+                stdout=Subprocess.STREAM,
+                stderr=Subprocess.STREAM
             )
+        except FileNotFoundError:
+            logger.warning('lsof command not found, cannot detect listening ports')
+            warning = 'lsof not installed'
+            return ports, warning
 
-            if result.returncode == 0:
-                # Parse lsof output
-                # Example line: python3  12345 user   3u  IPv4 0x1234  0t0  TCP *:8080 (LISTEN)
-                #               python3  12345 user   3u  IPv4 0x1234  0t0  TCP 127.0.0.1:8080 (LISTEN)
-                for line in result.stdout.split('\n'):
-                    if 'LISTEN' in line:
-                        # Extract port from patterns like:
-                        # *:PORT, 127.0.0.1:PORT, localhost:PORT, [::]:PORT
-                        # Port is always after the last colon before (LISTEN)
-                        match = re.search(r':(\d+)\s+\(LISTEN\)', line)
-                        if match:
-                            ports.add(int(match.group(1)))
-        except subprocess.SubprocessError as e:
+        try:
+            await with_timeout(timedelta(seconds=5), process.wait_for_exit(raise_error=True))
+        except tornado.gen.TimeoutError:
+            process.proc.kill()
+            await process.wait_for_exit(raise_error=False)
+            logger.warning('lsof command timed out')
+            warning = 'lsof timed out'
+            return ports, warning
+        except subprocess.CalledProcessError as e:
             # lsof may return exit code 1 if no results found, which is fine
             if e.returncode != 1:
                 raise
-        except FileNotFoundError:
-            logger.warning('lsof command not found, cannot detect listening ports')
-            warning = 'lsof not installed'
+            return ports, warning
+
+        # Parse lsof output
+        # Example line: python3  12345 user   3u  IPv4 0x1234  0t0  TCP *:8080 (LISTEN)
+        #               python3  12345 user   3u  IPv4 0x1234  0t0  TCP 127.0.0.1:8080 (LISTEN)
+        output = (await process.stdout.read_until_close()).decode('utf-8')
+        for line in output.split('\n'):
+            if 'LISTEN' in line:
+                # Extract port from patterns like:
+                # *:PORT, 127.0.0.1:PORT, localhost:PORT, [::]:PORT
+                # Port is always after the last colon before (LISTEN)
+                match = re.search(r':(\d+)\s+\(LISTEN\)', line)
+                if match:
+                    ports.add(int(match.group(1)))
 
         return ports, warning