Source code for evennia.scripts.tickerhandler

"""
TickerHandler

This implements an efficient Ticker which uses a subscription
model to 'tick' subscribed objects at regular intervals.

The ticker mechanism is used by importing and accessing
the instantiated TICKER_HANDLER instance in this module. This
instance is run by the server; it will save its status across
server reloads and be started automaticall on boot.

Example:

```python
    from evennia.scripts.tickerhandler import TICKER_HANDLER

    # call tick myobj.at_tick(*args, **kwargs) every 15 seconds
    TICKER_HANDLER.add(15, myobj.at_tick, *args, **kwargs)
```

You supply the interval to tick and a callable to call regularly with
any extra args/kwargs. The callable should either be a stand-alone
function in a module *or* the method on a *typeclassed* entity (that
is, on an object that can be safely and stably returned from the
database).  Functions that are dynamically created or sits on
in-memory objects cannot be used by the tickerhandler (there is no way
to reference them safely across reboots and saves).

The handler will transparently set
up and add new timers behind the scenes to tick at given intervals,
using a TickerPool - all callables with the same interval will share
the interval ticker.

To remove:

```python
    TICKER_HANDLER.remove(15, myobj.at_tick)
```

Both interval and callable must be given since a single object can be subscribed
to many different tickers at the same time. You can also supply `idstring`
as an identifying string if you ever want to tick the callable at the same interval
but with different arguments (args/kwargs are not used for identifying the ticker). There
is also `persistent=False` if you don't want to make a ticker that don't survive a reload.
If either or both `idstring` or `persistent` has been changed from their defaults, they
must be supplied to the `TICKER_HANDLER.remove` call to properly identify the ticker
to remove.

The TickerHandler's functionality can be overloaded by modifying the
Ticker class and then changing TickerPool and TickerHandler to use the
custom classes

```python
class MyTicker(Ticker):
    # [doing custom stuff]

class MyTickerPool(TickerPool):
    ticker_class = MyTicker
class MyTickerHandler(TickerHandler):
    ticker_pool_class = MyTickerPool
```

If one wants to duplicate TICKER_HANDLER's auto-saving feature in
a  custom handler one can make a custom `AT_STARTSTOP_MODULE` entry to
call the handler's `save()` and `restore()` methods when the server reboots.

"""

import inspect

from django.core.exceptions import ObjectDoesNotExist
from twisted.internet.defer import inlineCallbacks

from evennia.scripts.scripts import ExtendedLoopingCall
from evennia.server.models import ServerConfig
from evennia.utils import inherits_from, variable_from_module
from evennia.utils.dbserialize import dbserialize, dbunserialize, pack_dbobj
from evennia.utils.logger import log_err, log_trace

_GA = object.__getattribute__
_SA = object.__setattr__


_ERROR_ADD_TICKER = """TickerHandler: Tried to add an invalid ticker:
{store_key}
Ticker was not added."""

_ERROR_ADD_TICKER_SUB_SECOND = """You are trying to add a ticker running faster
than once per second. This is not supported and also probably not useful:
Spamming messages to the user faster than once per second serves no purpose in
a text-game, and if you want to update some property, consider doing so
on-demand rather than using a ticker.
"""


[docs]class Ticker(object): """ Represents a repeatedly running task that calls hooks repeatedly. Overload `_callback` to change the way it operates. """ @inlineCallbacks def _callback(self): """ This will be called repeatedly every `self.interval` seconds. `self.subscriptions` contain tuples of (obj, args, kwargs) for each subscribing object. If overloading, this callback is expected to handle all subscriptions when it is triggered. It should not return anything and should not traceback on poorly designed hooks. The callback should ideally work under @inlineCallbacks so it can yield appropriately. The _hook_key, which is passed down through the handler via kwargs is used here to identify which hook method to call. """ self._to_add = [] self._to_remove = [] self._is_ticking = True for store_key, (args, kwargs) in self.subscriptions.items(): callback = yield kwargs.pop("_callback", "at_tick") obj = yield kwargs.pop("_obj", None) try: if callable(callback): # call directly yield callback(*args, **kwargs) continue # try object method if not obj or not obj.pk: # object was deleted between calls self._to_remove.append(store_key) continue else: yield _GA(obj, callback)(*args, **kwargs) except ObjectDoesNotExist: log_trace("Removing ticker.") self._to_remove.append(store_key) except Exception: log_trace() finally: # make sure to re-store kwargs["_callback"] = callback kwargs["_obj"] = obj # cleanup - we do this here to avoid changing the subscription dict while it loops self._is_ticking = False for store_key in self._to_remove: self.remove(store_key) for store_key, (args, kwargs) in self._to_add: self.add(store_key, *args, **kwargs) self._to_remove = [] self._to_add = []
[docs] def __init__(self, interval): """ Set up the ticker Args: interval (int): The stepping interval. """ self.interval = interval self.subscriptions = {} self._is_ticking = False self._to_remove = [] self._to_add = [] # set up a twisted asynchronous repeat call self.task = ExtendedLoopingCall(self._callback)
[docs] def validate(self, start_delay=None): """ Start/stop the task depending on how many subscribers we have using it. Args: start_delay (int, optional): Time to way before starting. """ subs = self.subscriptions if self.task.running: if not subs: self.task.stop() elif subs: self.task.start(self.interval, now=False, start_delay=start_delay)
[docs] def add(self, store_key, *args, **kwargs): """ Sign up a subscriber to this ticker. Args: store_key (str): Unique storage hash for this ticker subscription. args (any, optional): Arguments to call the hook method with. Keyword Args: _start_delay (int): If set, this will be used to delay the start of the trigger instead of `interval`. """ if self._is_ticking: # protects the subscription dict from # updating while it is looping self._to_add.append((store_key, (args, kwargs))) else: start_delay = kwargs.pop("_start_delay", None) self.subscriptions[store_key] = (args, kwargs) self.validate(start_delay=start_delay)
[docs] def remove(self, store_key): """ Unsubscribe object from this ticker Args: store_key (str): Unique store key. """ if self._is_ticking: # this protects the subscription dict from # updating while it is looping self._to_remove.append(store_key) else: self.subscriptions.pop(store_key, False) self.validate()
[docs] def stop(self): """ Kill the Task, regardless of subscriptions. """ self.subscriptions = {} self.validate()
[docs]class TickerPool(object): """ This maintains a pool of `evennia.scripts.scripts.ExtendedLoopingCall` tasks for calling subscribed objects at given times. """ ticker_class = Ticker
[docs] def __init__(self): """ Initialize the pool. """ self.tickers = {}
[docs] def add(self, store_key, *args, **kwargs): """ Add new ticker subscriber. Args: store_key (str): Unique storage hash. args (any, optional): Arguments to send to the hook method. """ _, _, _, interval, _, _ = store_key if not interval: log_err(_ERROR_ADD_TICKER.format(store_key=store_key)) return if interval not in self.tickers: self.tickers[interval] = self.ticker_class(interval) self.tickers[interval].add(store_key, *args, **kwargs)
[docs] def remove(self, store_key): """ Remove subscription from pool. Args: store_key (str): Unique storage hash to remove """ _, _, _, interval, _, _ = store_key if interval in self.tickers: self.tickers[interval].remove(store_key) if not self.tickers[interval]: del self.tickers[interval]
[docs] def stop(self, interval=None): """ Stop all scripts in pool. This is done at server reload since restoring the pool will automatically re-populate the pool. Args: interval (int, optional): Only stop tickers with this interval. """ if interval and interval in self.tickers: self.tickers[interval].stop() else: for ticker in self.tickers.values(): ticker.stop()
[docs]class TickerHandler(object): """ The Tickerhandler maintains a pool of tasks for subscribing objects to various tick rates. The pool maintains creation instructions and and re-applies them at a server restart. """ ticker_pool_class = TickerPool
[docs] def __init__(self, save_name="ticker_storage"): """ Initialize handler save_name (str, optional): The name of the ServerConfig instance to store the handler state persistently. """ self.ticker_storage = {} self.save_name = save_name self.ticker_pool = self.ticker_pool_class()
def _get_callback(self, callback): """ Analyze callback and determine its consituents Args: callback (function or method): This is either a stand-alone function or class method on a typeclassed entitye (that is, an entity that can be saved to the database). Returns: ret (tuple): This is a tuple of the form `(obj, path, callfunc)`, where `obj` is the database object the callback is defined on if it's a method (otherwise `None`) and vice-versa, `path` is the python-path to the stand-alone function (`None` if a method). The `callfunc` is either the name of the method to call or the callable function object itself. Raises: TypeError: If the callback is of an unsupported type. """ outobj, outpath, outcallfunc = None, None, None if callable(callback): if inspect.ismethod(callback): outobj = callback.__self__ outcallfunc = callback.__func__.__name__ elif inspect.isfunction(callback): outpath = "%s.%s" % (callback.__module__, callback.__name__) outcallfunc = callback else: raise TypeError(f"{callback} is not a method or function.") else: raise TypeError(f"{callback} is not a callable function or method.") if outobj and not inherits_from(outobj, "evennia.typeclasses.models.TypedObject"): raise TypeError( f"{callback} is a method on a normal object - it must " "be either a method on a typeclass, or a stand-alone function." ) return outobj, outpath, outcallfunc def _store_key(self, obj, path, interval, callfunc, idstring="", persistent=True): """ Tries to create a store_key for the object. Args: obj (Object, tuple or None): Subscribing object if any. If a tuple, this is a packed_obj tuple from dbserialize. path (str or None): Python-path to callable, if any. interval (int): Ticker interval. Floats will be converted to nearest lower integer value. callfunc (callable or str): This is either the callable function or the name of the method to call. Note that the callable is never stored in the key; that is uniquely identified with the python-path. idstring (str, optional): Additional separator between different subscription types. persistent (bool, optional): If this ticker should survive a system shutdown or not. Returns: store_key (tuple): A tuple `(packed_obj, methodname, outpath, interval, idstring, persistent)` that uniquely identifies the ticker. Here, `packed_obj` is the unique string representation of the object or `None`. The `methodname` is the string name of the method on `packed_obj` to call, or `None` if `packed_obj` is unset. `path` is the Python-path to a non-method callable, or `None`. Finally, `interval` `idstring` and `persistent` are integers, strings and bools respectively. """ if interval < 1: raise RuntimeError(_ERROR_ADD_TICKER_SUB_SECOND) interval = int(interval) persistent = bool(persistent) packed_obj = pack_dbobj(obj) methodname = callfunc if callfunc and isinstance(callfunc, str) else None outpath = path if path and isinstance(path, str) else None return (packed_obj, methodname, outpath, interval, idstring, persistent)
[docs] def save(self): """ Save ticker_storage as a serialized string into a temporary ServerConf field. Whereas saving is done on the fly, if called by server when it shuts down, the current timer of each ticker will be saved so it can start over from that point. """ if self.ticker_storage: # get the current times so the tickers can be restarted with a delay later start_delays = dict( (interval, ticker.task.next_call_time()) for interval, ticker in self.ticker_pool.tickers.items() ) to_save = {} # remove any subscription that lost its object and update the timers for the tickers for store_key, (args, kwargs) in self.ticker_storage.items(): # unpack the store_key to reference its parts packedobj, callfunc, path, interval, idstring, persistent = store_key # verify that there's a valid obj+method or function path if ( callfunc and ("_obj" in kwargs and kwargs["_obj"].pk) and hasattr(kwargs["_obj"], callfunc) ) or path: # this is a mutable, so it's updated in-place in ticker_storage kwargs["_start_delay"] = start_delays.get(interval, None) to_save[store_key] = (args, kwargs) ServerConfig.objects.conf(key=self.save_name, value=dbserialize(to_save)) else: # make sure we have nothing lingering in the database ServerConfig.objects.conf(key=self.save_name, delete=True)
[docs] def restore(self, server_reload=True): """ Restore ticker_storage from database and re-initialize the handler from storage. This is triggered by the server at restart. Args: server_reload (bool, optional): If this is False, it means the server went through a cold reboot and all non-persistent tickers must be killed. """ # load stored command instructions and use them to re-initialize handler restored_tickers = ServerConfig.objects.conf(key=self.save_name) if restored_tickers: # the dbunserialize will convert all serialized dbobjs to real objects restored_tickers = dbunserialize(restored_tickers) self.ticker_storage = {} for store_key, (args, kwargs) in restored_tickers.items(): try: # at this point obj is the actual object (or None) due to how # the dbunserialize works obj, callfunc, path, interval, idstring, persistent = store_key if not persistent and not server_reload: # this ticker will not be restarted continue if isinstance(callfunc, str) and not obj: # methods must have an existing object continue # we must rebuild the store_key here since obj must not be # stored as the object itself for the store_key to be hashable. store_key = self._store_key(obj, path, interval, callfunc, idstring, persistent) if obj and callfunc: kwargs["_callback"] = callfunc kwargs["_obj"] = obj elif path: modname, varname = path.rsplit(".", 1) callback = variable_from_module(modname, varname) kwargs["_callback"] = callback kwargs["_obj"] = None else: # Neither object nor path - discard this ticker log_err("Tickerhandler: Removing malformed ticker: %s" % str(store_key)) continue except Exception: # this suggests a malformed save or missing objects log_trace("Tickerhandler: Removing malformed ticker: %s" % str(store_key)) continue # if we get here we should create a new ticker self.ticker_storage[store_key] = (args, kwargs) self.ticker_pool.add(store_key, *args, **kwargs)
[docs] def add(self, interval=60, callback=None, idstring="", persistent=True, *args, **kwargs): """ Add subscription to tickerhandler Args: *args: Will be passed into the callback every time it's called. This must be data possible to pickle. Keyword Args: interval (int): Interval in seconds between calling `callable(*args, **kwargs)` callable (callable function or method): This should either be a stand-alone function or a method on a typeclassed entity (that is, one that can be saved to the database). idstring (str): Identifier for separating this ticker-subscription from others with the same interval. Allows for managing multiple calls with the same time interval and callback. persistent (bool): A ticker will always survive a server reload. If this is unset, the ticker will be deleted by a server shutdown. **kwargs Will be passed into the callback every time it is called. This must be data possible to pickle. Returns: store_key (tuple): The immutable store-key for this ticker. This can be stored and passed into `.remove(store_key=store_key)` later to easily stop this ticker later. Notes: The callback will be identified by type and stored either as as combination of serialized database object + methodname or as a python-path to the module + funcname. These strings will be combined iwth `interval` and `idstring` to define a unique storage key for saving. These must thus all be supplied when wanting to modify/remove the ticker later. """ obj, path, callfunc = self._get_callback(callback) store_key = self._store_key(obj, path, interval, callfunc, idstring, persistent) kwargs["_obj"] = obj kwargs["_callback"] = callfunc # either method-name or callable self.ticker_storage[store_key] = (args, kwargs) self.ticker_pool.add(store_key, *args, **kwargs) self.save() return store_key
[docs] def remove(self, interval=60, callback=None, idstring="", persistent=True, store_key=None): """ Remove ticker subscription from handler. Keyword Args: interval (int): Interval of ticker to remove. callback (callable function or method): Either a function or the method of a typeclassed object. idstring (str): Identifier id of ticker to remove. persistent (bool): Whether this ticker is persistent or not. store_key (str): If given, all other kwargs are ignored and only this is used to identify the ticker. Raises: KeyError: If no matching ticker was found to remove. Notes: The store-key is normally built from the interval/callback/idstring/persistent values; but if the `store_key` is explicitly given, this is used instead. """ if isinstance(callback, int): raise RuntimeError( "TICKER_HANDLER.remove has changed: " "the interval is now the first argument, callback the second." ) if not store_key: obj, path, callfunc = self._get_callback(callback) store_key = self._store_key(obj, path, interval, callfunc, idstring, persistent) to_remove = self.ticker_storage.pop(store_key, None) if to_remove: self.ticker_pool.remove(store_key) self.save() else: raise KeyError(f"No Ticker was found matching the store-key {store_key}.")
[docs] def clear(self, interval=None): """ Stop/remove tickers from handler. Args: interval (int, optional): Only stop tickers with this interval. Notes: This is the only supported way to kill tickers related to non-db objects. """ self.ticker_pool.stop(interval) if interval: self.ticker_storage = dict( (store_key, store_value) for store_key, store_value in self.ticker_storage.items() if store_key[3] != interval ) else: self.ticker_storage = {} self.save()
[docs] def all(self, interval=None): """ Get all ticker subscriptions. Args: interval (int, optional): Limit match to tickers with this interval. Returns: list or dict: If `interval` was given, this is a list of tickers using that interval. If `interval` was *not* given, this is a dict `{interval1: [ticker1, ticker2, ...], ...}` """ if interval is None: # return dict of all, ordered by interval return dict( (interval, ticker.subscriptions) for interval, ticker in self.ticker_pool.tickers.items() ) else: # get individual interval ticker = self.ticker_pool.tickers.get(interval, None) if ticker: return {interval: ticker.subscriptions} return None
[docs] def all_display(self): """ Get all tickers on an easily displayable form. Returns: tickers (dict): A list of all storekeys """ store_keys = [] for ticker in self.ticker_pool.tickers.values(): for ( (objtup, callfunc, path, interval, idstring, persistent), (args, kwargs), ) in ticker.subscriptions.items(): store_keys.append( (kwargs.get("_obj", None), callfunc, path, interval, idstring, persistent) ) return store_keys
# main tickerhandler TICKER_HANDLER = TickerHandler()