"""
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 twisted.internet.defer import inlineCallbacks
from django.core.exceptions import ObjectDoesNotExist
from evennia.scripts.scripts import ExtendedLoopingCall
from evennia.server.models import ServerConfig
from evennia.utils.logger import log_trace, log_err
from evennia.utils.dbserialize import dbserialize, dbunserialize, pack_dbobj
from evennia.utils import variable_from_module, inherits_from
_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): 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()
)
# remove any subscriptions that lost its object in the interim
to_save = {
store_key: (args, kwargs)
for store_key, (args, kwargs) in self.ticker_storage.items()
if (
(
store_key[1]
and ("_obj" in kwargs and kwargs["_obj"].pk)
and hasattr(kwargs["_obj"], store_key[1])
)
or store_key[2] # a valid method with existing obj
)
} # a path given
# update the timers for the tickers
for store_key, (args, kwargs) in to_save.items():
interval = store_key[1]
# this is a mutable, so it's updated in-place in ticker_storage
kwargs["_start_delay"] = start_delays.get(interval, None)
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:
interval (int, optional): Interval in seconds between calling
`callable(*args, **kwargs)`
callable (callable function or method, optional): 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, optional): 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, optional): A ticker will always survive
a server reload. If this is unset, the ticker will be
deleted by a server shutdown.
args, kwargs (optional): These 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.
Args:
interval (int, optional): Interval of ticker to remove.
callback (callable function or method): Either a function or
the method of a typeclassed object.
idstring (str, optional): Identifier id of ticker to remove.
persistent (bool, optional): Whether this ticker is persistent or not.
store_key (str, optional): 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): 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_key)
for store_key in self.ticker_storage
if store_key[1] != interval
)
else:
self.ticker_storage = {}
self.save()
[docs] def all(self, interval=None):
"""
Get all subscriptions.
Args:
interval (int): Limit match to tickers with this interval.
Returns:
tickers (list): If `interval` was given, this is a list of
tickers using that interval.
tickerpool_layout (dict): 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()
