def __init__(self, interval):
"""
Set up the ticker
"""
self.interval = interval
self.subscriptions = {}
# set up a twisted asynchronous repeat call
self.task = ExtendedLoopingCall(self._callback)
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.
"""
for key, (obj, args, kwargs) in self.subscriptions.items():
hook_key = yield kwargs.get("hook_key", "at_tick")
if not obj:
# object was deleted between calls
self.validate()
continue
try:
yield _GA(obj, hook_key)(*args, **kwargs)
except Exception:
log_trace()
def __init__(self, interval):
"""
Set up the ticker
"""
self.interval = interval
self.subscriptions = {}
# set up a twisted asynchronous repeat call
self.task = ExtendedLoopingCall(self._callback)
def validate(self, start_delay=None):
"""
Start/stop the task depending on how many
subscribers we have using it.
"""
subs = self.subscriptions
if None in subs.values():
# clean out objects that may have been deleted
subs = dict((store_key, obj) for store_key, obj in subs if obj)
self.subscriptions = subs
if self.task.running:
if not subs:
self.task.stop()
elif subs:
#print "starting with start_delay=", start_delay
self.task.start(self.interval, now=False, start_delay=start_delay)
def add(self, store_key, obj, *args, **kwargs):
"""
Sign up a subscriber to this ticker. If kwargs contains
a keyword _start_delay, this will be used to delay the start
of the trigger instead of interval.
"""
start_delay = kwargs.pop("_start_delay", None)
self.subscriptions[store_key] = (obj, args, kwargs)
self.validate(start_delay=start_delay)
def remove(self, store_key):
"""
Unsubscribe object from this ticker
"""
self.subscriptions.pop(store_key, False)
self.validate()
def stop(self):
"""
Kill the Task, regardless of subscriptions
"""
self.subscriptions = {}
self.validate()
