Add signals

Fixes #219

django_q/cluster.py

@@ -34,6 +34,7 @@ from django_q.conf import Conf, logger, psutil, get_ppid, rollbar
 from django_q.models import Task, Success, Schedule
 from django_q.status import Stat, Status
 from django_q.brokers import get_broker
+from django_q.signals import pre_execute
 
 
 class Cluster(object):
@@ -373,8 +374,11 @@ def worker(task_queue, result_queue, timer, timeout=Conf.TIMEOUT):
         # We're still going
         if not result:
             db.close_old_connections()
+            timer_value = task['kwargs'].pop('timeout', timeout or 0)
+            # signal execution
+            pre_execute.send(sender="django_q", func=f, task=task)
             # execute the payload
-            timer.value = task['kwargs'].pop('timeout', timeout or 0)  # Busy
+            timer.value = timer_value  # Busy
             try:
                 res = f(*task['args'], **task['kwargs'])
                 result = (res, True)