misc: fix locking in clean_sessions (#47127)

wcs/qommon/publisher.py

@@ -588,42 +588,37 @@ class QommonPublisher(Publisher, object):
 
     def clean_sessions(self):
         cleaning_lock_file = os.path.join(self.app_dir, 'cleaning_sessions.lock')
-        fd = os.open(cleaning_lock_file, os.O_RDONLY | os.O_CREAT, 0o666)
         try:
-            fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
-        except IOError:
-            # lock is currently held, that is fine.
-            return
-        try:
-            manager = self.session_manager_class(session_class=self.session_class)
-            now = time.time()
-            last_usage_limit = now - 3*86400
-            creation_limit = now - 30*86400
-            for session_key in manager.keys():
-                try:
-                    session = manager.get(session_key)
-                    if session._access_time < last_usage_limit or session._creation_time < creation_limit:
-                        del manager[session.id]
-                except (AttributeError, KeyError):
-                    # the key is impossible to load or the session is malformed
-                    # delete it anyway, but only catch KeyError (other errors could be useful)
+            with locket.lock_file(cleaning_lock_file, timeout=0):
+                manager = self.session_manager_class(session_class=self.session_class)
+                now = time.time()
+                last_usage_limit = now - 3*86400
+                creation_limit = now - 30*86400
+                for session_key in manager.keys():
                     try:
-                        del manager[session_key]
-                    except KeyError:
-                        pass
-                    continue
-            # also delete obsolete form_tokens that would have be missed when
-            # cleaning sessions.
-            form_tokens_dir = self.form_tokens_dir
-            if os.path.exists(form_tokens_dir):
-                for filename in os.listdir(form_tokens_dir):
-                    try:
-                        if os.stat(os.path.join(form_tokens_dir, filename)).st_mtime < creation_limit:
-                            os.unlink(os.path.join(form_tokens_dir, filename))
-                    except FileNotFoundError:
-                        pass
-        finally:
-            os.close(fd)
+                        session = manager.get(session_key)
+                        if session._access_time < last_usage_limit or session._creation_time < creation_limit:
+                            del manager[session.id]
+                    except (AttributeError, KeyError):
+                        # the key is impossible to load or the session is malformed
+                        # delete it anyway, but only catch KeyError (other errors could be useful)
+                        try:
+                            del manager[session_key]
+                        except KeyError:
+                            pass
+                        continue
+                # also delete obsolete form_tokens that would have be missed when
+                # cleaning sessions.
+                form_tokens_dir = self.form_tokens_dir
+                if os.path.exists(form_tokens_dir):
+                    for filename in os.listdir(form_tokens_dir):
+                        try:
+                            if os.stat(os.path.join(form_tokens_dir, filename)).st_mtime < creation_limit:
+                                os.unlink(os.path.join(form_tokens_dir, filename))
+                        except FileNotFoundError:
+                            pass
+        except locket.LockError:
+            pass
 
     def clean_afterjobs(self):
         now = time.time()