/
pyemitter.py
222 lines (150 loc) · 5.74 KB
/
pyemitter.py
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import logging
import traceback
# concurrent.futures is optional
try:
from concurrent.futures import ThreadPoolExecutor
except ImportError:
ThreadPoolExecutor = None
log = logging.getLogger(__name__)
class Emitter(object):
threading = False
threading_workers = 2
__constructed = False
__name = None
__callbacks = None
__threading_pool = None
def __ensure_constructed(self):
if self.__constructed:
return
self.__callbacks = {}
self.__constructed = True
if self.threading:
if ThreadPoolExecutor is None:
raise Exception('concurrent.futures is required for threading')
self.__threading_pool = ThreadPoolExecutor(max_workers=self.threading_workers)
def __log(self, message, *args, **kwargs):
if self.__name is None:
self.__name = '%s.%s' % (
self.__module__,
self.__class__.__name__
)
log.debug(
('[%s]:' % self.__name.ljust(34)) + str(message),
*args, **kwargs
)
def __wrap(self, callback, *args, **kwargs):
def wrap(func):
callback(func=func, *args, **kwargs)
return func
return wrap
def on(self, events, func=None, on_bound=None):
if not func:
# assume decorator, wrap
return self.__wrap(self.on, events, on_bound=on_bound)
if not isinstance(events, (list, tuple)):
events = [events]
self.__log('on(events: %s, func: %s)', repr(events), repr(func))
self.__ensure_constructed()
for event in events:
if event not in self.__callbacks:
self.__callbacks[event] = []
# Bind callback to event
self.__callbacks[event].append(func)
# Call 'on_bound' callback
if on_bound:
self.__call(on_bound, kwargs={
'func': func
})
return self
def once(self, event, func=None):
if not func:
# assume decorator, wrap
return self.__wrap(self.once, event)
self.__log('once(event: %s, func: %s)', repr(event), repr(func))
def once_callback(*args, **kwargs):
self.off(event, once_callback)
func(*args, **kwargs)
self.on(event, once_callback)
return self
def off(self, event=None, func=None):
self.__log('off(event: %s, func: %s)', repr(event), repr(func))
self.__ensure_constructed()
if event and event not in self.__callbacks:
return self
if func and func not in self.__callbacks[event]:
return self
if event and func:
self.__callbacks[event].remove(func)
elif event:
self.__callbacks[event] = []
elif func:
raise ValueError('"event" is required if "func" is specified')
else:
self.__callbacks = {}
return self
def emit(self, event, *args, **kwargs):
suppress = kwargs.pop('__suppress', False)
if not suppress:
self.__log('emit(event: %s, args: %s, kwargs: %s)', repr(event), repr_trim(args), repr_trim(kwargs))
self.__ensure_constructed()
if event not in self.__callbacks:
return
for callback in list(self.__callbacks[event]):
self.__call(callback, args, kwargs, event)
return self
def emit_on(self, event, *args, **kwargs):
func = kwargs.pop('func', None)
if not func:
# assume decorator, wrap
return self.__wrap(self.emit_on, event, *args, **kwargs)
self.__log('emit_on(event: %s, func: %s, args: %s, kwargs: %s)', repr(event), repr(func), repr(args), repr(kwargs))
# Bind func from wrapper
self.on(event, func)
# Emit event (calling 'func')
self.emit(event, *args, **kwargs)
def pipe(self, events, other):
if type(events) is not list:
events = [events]
self.__log('pipe(events: %s, other: %s)', repr(events), repr(other))
self.__ensure_constructed()
for event in events:
self.on(event, PipeHandler(event, other.emit))
return self
def __call(self, callback, args=None, kwargs=None, event=None):
args = args or ()
kwargs = kwargs or {}
if self.threading:
return self.__call_async(callback, args, kwargs, event)
return self.__call_sync(callback, args, kwargs, event)
@staticmethod
def __call_sync(callback, args=None, kwargs=None, event=None):
try:
callback(*args, **kwargs)
return True
except Exception as ex:
log.warn('Exception raised in callback %s for event "%s" - %s', callback, event, traceback.format_exc())
return False
def __call_async(self, callback, args=None, kwargs=None, event=None):
self.__threading_pool.submit(self.__call_sync, callback, args, kwargs, event)
class PipeHandler(object):
def __init__(self, event, callback):
self.event = event
self.callback = callback
def __call__(self, *args, **kwargs):
self.callback(self.event, *args, **kwargs)
def on(emitter, event, func=None):
emitter.on(event, func)
return {
'destroy': lambda: emitter.off(event, func)
}
def once(emitter, event, func=None):
return emitter.once(event, func)
def off(emitter, event, func=None):
return emitter.off(event, func)
def emit(emitter, event, *args, **kwargs):
return emitter.emit(event, *args, **kwargs)
def repr_trim(value, length=1000):
value = repr(value)
if len(value) < length:
return value
return '<%s - %s characters>' % (type(value).__name__, len(value))