|
"""Helper functinos for working with signals"""
from twisted.internet.defer import maybeDeferred, DeferredList, Deferred
from twisted.python.failure import Failure
from scrapy.xlib.pydispatch.dispatcher import Any, Anonymous, liveReceivers, \
getAllReceivers, disconnect
from scrapy.xlib.pydispatch.robustapply import robustApply
from scrapy import log
def send_catch_log(signal=Any, sender=Anonymous, *arguments, **named):
"""Like pydispatcher.robust.sendRobust but it also logs errors and returns
Failures instead of exceptions.
"""
dont_log = named.pop('dont_log', None)
spider = named.get('spider', None)
responses = []
for receiver in liveReceivers(getAllReceivers(sender, signal)):
try:
response = robustApply(receiver, signal=signal, sender=sender,
*arguments, **named)
if isinstance(response, Deferred):
log.msg("Cannot return deferreds from signal handler: %s" % \
receiver, log.ERROR, spider=spider)
except dont_log:
result = Failure()
except Exception:
result = Failure()
log.err(result, "Error caught on signal handler: %s" % receiver, \
spider=spider)
else:
result = response
responses.append((receiver, result))
return responses
def send_catch_log_deferred(signal=Any, sender=Anonymous, *arguments, **named):
"""Like send_catch_log but supports returning deferreds on signal handlers.
Returns a deferred that gets fired once all signal handlers deferreds were
fired.
"""
def logerror(failure, recv):
46 if dont_log is None or not isinstance(failure.value, dont_log):
log.err(failure, "Error caught on signal handler: %s" % recv, \
spider=spider)
return failure
dont_log = named.pop('dont_log', None)
spider = named.get('spider', None)
dfds = []
for receiver in liveReceivers(getAllReceivers(sender, signal)):
d = maybeDeferred(robustApply, receiver, signal=signal, sender=sender,
*arguments, **named)
d.addErrback(logerror, receiver)
d.addBoth(lambda result: (receiver, result))
dfds.append(d)
d = DeferredList(dfds)
d.addCallback(lambda out: [x[1] for x in out])
return d
def disconnect_all(signal=Any, sender=Any):
"""Disconnect all signal handlers. Useful for cleaning up after running
tests
"""
for receiver in liveReceivers(getAllReceivers(sender, signal)):
disconnect(receiver, signal=signal, sender=sender)
|
