Fix edge case in TaskHandler when un-pickleable callable supplied

evennia/scripts/taskhandler.py

@@ -5,6 +5,7 @@ Module containing the task handler for Evennia deferred tasks, persistent or not
 from datetime import datetime, timedelta
 
 from twisted.internet import reactor
+from pickle import PickleError
 from twisted.internet.task import deferLater
 from twisted.internet.defer import CancelledError as DefCancelledError
 from evennia.server.models import ServerConfig
@@ -287,18 +288,8 @@ class TaskHandler(object):
             # Check if callback can be pickled. args and kwargs have been checked
             safe_callback = None
 
-            try:
-                dbserialize(callback)
-            except (TypeError, AttributeError):
-                raise ValueError(
-                    "the specified callback {} cannot be pickled. "
-                    "It must be a top-level function in a module or an "
-                    "instance method.".format(callback)
-                )
-            else:
-                safe_callback = callback
 
-            self.to_save[task_id] = dbserialize((date, safe_callback, args, kwargs))
+            self.to_save[task_id] = dbserialize((date, callback, args, kwargs))
         ServerConfig.objects.conf("delayed_tasks", self.to_save)
 
     def add(self, timedelay, callback, *args, **kwargs):
@@ -318,8 +309,8 @@ class TaskHandler(object):
             any (any): any additional positional arguments to send to the callback
             *args: positional arguments to pass to callback.
             **kwargs: keyword arguments to pass to callback.
-                persistent (bool, optional): persist the task (stores it).
-                    persistent key and value is removed from kwargs it will
+                - persistent (bool, optional): persist the task (stores it).
+                    Persistent key and value is removed from kwargs it will
                     not be passed to callback.
 
         Returns:
@@ -346,11 +337,22 @@ class TaskHandler(object):
             safe_args = []
             safe_kwargs = {}
 
+            # an unsaveable callback should immediately abort
+            try:
+                dbserialize(callback)
+            except (TypeError, AttributeError, PickleError):
+                raise ValueError(
+                    "the specified callback {} cannot be pickled. "
+                    "It must be a top-level function in a module or an "
+                    "instance method.".format(callback)
+                )
+                return
+
             # Check that args and kwargs contain picklable information
             for arg in args:
                 try:
                     dbserialize(arg)
-                except (TypeError, AttributeError):
+                except (TypeError, AttributeError, PickleError):
                     log_err(
                         "The positional argument {} cannot be "
                         "pickled and will not be present in the arguments "
@@ -362,7 +364,7 @@ class TaskHandler(object):
             for key, value in kwargs.items():
                 try:
                     dbserialize(value)
-                except (TypeError, AttributeError):
+                except (TypeError, AttributeError, PickleError):
                     log_err(
                         "The {} keyword argument {} cannot be "
                         "pickled and will not be present in the arguments "

evennia/utils/utils.py

@@ -1030,20 +1030,19 @@ def delay(timedelay, callback, *args, **kwargs):
             after `timedelay` seconds.
         args (any, optional): Will be used as arguments to callback
     Keyword Args:
-        persistent (bool, optional): should make the delay persistent
-            over a reboot or reload
+        persistent (bool, optional): Should make the delay persistent
+            over a reboot or reload. Defaults to False.
         any (any): Will be used as keyword arguments to callback.
 
     Returns:
-        deferred (deferred): Will fire with callback after
-            `timedelay` seconds. Note that if `timedelay()` is used in the
-            commandhandler callback chain, the callback chain can be
-            defined directly in the command body and don't need to be
-            specified here.
-            Reference twisted.internet.defer.Deferred
-        if persistent kwarg is truthy:
-        task_id (int): the task's id intended for use with
-          evennia.scripts.taskhandler.TASK_HANDLER's do_task and remove methods.
+        deferred or int: If ``persistent`` kwarg is `False`, return deferred
+            that will fire with callback after `timedelay` seconds. Note that
+            if `timedelay()` is used in the commandhandler callback chain, the
+            callback chain can be defined directly in the command body and
+            don't need to be specified here. Reference twisted.internet.defer.Deferred.
+            If persistent kwarg is set, return the task's ID as an integer. This is
+            intended for use with ``evennia.scripts.taskhandler.TASK_HANDLER``
+            `.do_task` and `.remove` methods.
 
     Note:
         The task handler (`evennia.scripts.taskhandler.TASK_HANDLER`) will