planetstack/openstack_observer/event_loop.py - xos - Gitiles

 import os
 import imp
 import inspect
 import time
 import sys
 import traceback
 import commands
 import threading
 import json
 import pdb
 import pprint


 from datetime import datetime
 from collections import defaultdict
 from core.models import *
 from django.db.models import F, Q
 from django.db import connection
 #from openstack.manager import OpenStackManager
 from openstack.driver import OpenStackDriver
 from util.logger import Logger, logging, logger
 #from timeout import timeout
 from xos.config import Config, XOS_DIR
 from observer.steps import *
 from syncstep import SyncStep
 from toposort import toposort
 from observer.error_mapper import *
 from openstack_observer.openstacksyncstep import OpenStackSyncStep


 debug_mode = False

 class bcolors:
     HEADER = '\033[95m'
     OKBLUE = '\033[94m'
     OKGREEN = '\033[92m'
     WARNING = '\033[93m'
     FAIL = '\033[91m'
     ENDC = '\033[0m'
     BOLD = '\033[1m'
     UNDERLINE = '\033[4m'

 logger = Logger(level=logging.INFO)

 class StepNotReady(Exception):
 	pass

 class NoOpDriver:
 	def __init__(self):
 		 self.enabled = True
 		 self.dependency_graph = None

 STEP_STATUS_WORKING=1
 STEP_STATUS_OK=2
 STEP_STATUS_KO=3

 def invert_graph(g):
 	ig = {}
 	for k,v in g.items():
 		for v0 in v:
 			try:
 				ig[v0].append(k)
 			except:
 				ig=[k]
 	return ig

 class XOSObserver:
 	#sync_steps = [SyncNetworks,SyncNetworkSlivers,SyncSites,SyncSitePrivilege,SyncSlices,SyncSliceMemberships,SyncSlivers,SyncSliverIps,SyncExternalRoutes,SyncUsers,SyncRoles,SyncNodes,SyncImages,GarbageCollector]
 	sync_steps = []


 	def __init__(self):
 		# The Condition object that gets signalled by Feefie events
 		self.step_lookup = {}
 		self.load_sync_step_modules()
 		self.load_sync_steps()
 		self.event_cond = threading.Condition()

 		self.driver_kind = getattr(Config(), "observer_driver", "openstack")
 		if self.driver_kind=="openstack":
 			self.driver = OpenStackDriver()
 		else:
 			self.driver = NoOpDriver()

 	def wait_for_event(self, timeout):
 		self.event_cond.acquire()
 		self.event_cond.wait(timeout)
 		self.event_cond.release()

 	def wake_up(self):
 		logger.info('Wake up routine called. Event cond %r'%self.event_cond)
 		self.event_cond.acquire()
 		self.event_cond.notify()
 		self.event_cond.release()

 	def load_sync_step_modules(self, step_dir=None):
 		if step_dir is None:
 			if hasattr(Config(), "observer_steps_dir"):
 				step_dir = Config().observer_steps_dir
 			else:
 				step_dir = XOS_DIR + "/observer/steps"

 		for fn in os.listdir(step_dir):
 			pathname = os.path.join(step_dir,fn)
 			if os.path.isfile(pathname) and fn.endswith(".py") and (fn!="__init__.py"):
 				module = imp.load_source(fn[:-3],pathname)
 				for classname in dir(module):
 					c = getattr(module, classname, None)

 					# make sure 'c' is a descendent of SyncStep and has a
 					# provides field (this eliminates the abstract base classes
 					# since they don't have a provides)

 					if inspect.isclass(c) and (issubclass(c, SyncStep) or issubclass(c,OpenStackSyncStep)) and hasattr(c,"provides") and (c not in self.sync_steps):
 						self.sync_steps.append(c)
 		logger.info('loaded sync steps: %s' % ",".join([x.__name__ for x in self.sync_steps]))
 		# print 'loaded sync steps: %s' % ",".join([x.__name__ for x in self.sync_steps])

 	def load_sync_steps(self):
 		dep_path = Config().observer_dependency_graph
 		logger.info('Loading model dependency graph from %s' % dep_path)
 		try:
 			# This contains dependencies between records, not sync steps
 			self.model_dependency_graph = json.loads(open(dep_path).read())
 			for left,lst in self.model_dependency_graph.items():
                                 new_lst = []
 				for k in lst:
 					try:
                                                 tup = (k,k.lower())
                                                 new_lst.append(tup)
 						deps = self.model_dependency_graph[k]
 					except:
 						self.model_dependency_graph[k] = []

                                 self.model_dependency_graph[left] = new_lst
 		except Exception,e:
 			raise e

 		try:
 			backend_path = Config().observer_pl_dependency_graph
 			logger.info('Loading backend dependency graph from %s' % backend_path)
 			# This contains dependencies between backend records
 			self.backend_dependency_graph = json.loads(open(backend_path).read())
 			for k,v in self.backend_dependency_graph.items():
 				try:
 					self.model_dependency_graph[k].extend(v)
 				except KeyError:
 					self.model_dependency_graphp[k] = v

 		except Exception,e:
 			logger.info('Backend dependency graph not loaded')
 			# We can work without a backend graph
 			self.backend_dependency_graph = {}

 		provides_dict = {}
 		for s in self.sync_steps:
 			self.step_lookup[s.__name__] = s
 			for m in s.provides:
 				try:
 					provides_dict[m.__name__].append(s.__name__)
 				except KeyError:
 					provides_dict[m.__name__]=[s.__name__]

 		step_graph = {}
 		for k,v in self.model_dependency_graph.items():
 			try:
 				for source in provides_dict[k]:
 					if (not v):
 						step_graph[source] = []

 					for m,_ in v:
 						try:
 							for dest in provides_dict[m]:
 								# no deps, pass
 								try:
 									if (dest not in step_graph[source]):
 										step_graph[source].append(dest)
 								except:
 									step_graph[source]=[dest]
 						except KeyError:
 							pass

 			except KeyError:
 				pass
 				# no dependencies, pass


 		self.dependency_graph = step_graph
 		self.deletion_dependency_graph = invert_graph(step_graph)

 		pp = pprint.PrettyPrinter(indent=4)
 		pp.pprint(step_graph)
 		self.ordered_steps = toposort(self.dependency_graph, map(lambda s:s.__name__,self.sync_steps))
 		#self.ordered_steps = ['SyncRoles', 'SyncControllerSites', 'SyncControllerSitePrivileges','SyncImages', 'SyncControllerImages','SyncControllerUsers','SyncControllerUserSitePrivileges','SyncControllerSlices', 'SyncControllerSlicePrivileges', 'SyncControllerUserSlicePrivileges', 'SyncControllerNetworks','SyncSlivers']
 		#self.ordered_steps = ['SyncControllerSites','SyncControllerUsers','SyncControllerSlices','SyncControllerNetworks']

 		print "Order of steps=",self.ordered_steps

 		self.load_run_times()


 	def check_duration(self, step, duration):
 		try:
 			if (duration > step.deadline):
 				logger.info('Sync step %s missed deadline, took %.2f seconds'%(step.name,duration))
 		except AttributeError:
 			# S doesn't have a deadline
 			pass

 	def update_run_time(self, step, deletion):
 		if (not deletion):
 			self.last_run_times[step.__name__]=time.time()
 		else:
 			self.last_deletion_run_times[step.__name__]=time.time()


 	def check_schedule(self, step, deletion):
 		last_run_times = self.last_run_times if not deletion else self.last_deletion_run_times

 		time_since_last_run = time.time() - last_run_times.get(step.__name__, 0)
 		try:
 			if (time_since_last_run < step.requested_interval):
 				raise StepNotReady
 		except AttributeError:
 			logger.info('Step %s does not have requested_interval set'%step.__name__)
 			raise StepNotReady

 	def load_run_times(self):
 		try:
 			jrun_times = open('/tmp/observer_run_times').read()
 			self.last_run_times = json.loads(jrun_times)
 		except:
 			self.last_run_times={}
 			for e in self.ordered_steps:
 				self.last_run_times[e]=0
 		try:
 			jrun_times = open('/tmp/observer_deletion_run_times').read()
 			self.last_deletion_run_times = json.loads(jrun_times)
 		except:
 			self.last_deletion_run_times={}
 			for e in self.ordered_steps:
 				self.last_deletion_run_times[e]=0


 	def save_run_times(self):
 		run_times = json.dumps(self.last_run_times)
 		open('/tmp/observer_run_times','w').write(run_times)

 		deletion_run_times = json.dumps(self.last_deletion_run_times)
 		open('/tmp/observer_deletion_run_times','w').write(deletion_run_times)

 	def check_class_dependency(self, step, failed_steps):
 		step.dependenices = []
 		for obj in step.provides:
 		        lst = self.model_dependency_graph.get(obj.__name__, [])
 			nlst = map(lambda(a,b):b,lst)
 			step.dependenices.extend(nlst)
 		for failed_step in failed_steps:
 			if (failed_step in step.dependencies):
 				raise StepNotReady

 	def sync(self, S, deletion):
             try:
 		step = self.step_lookup[S]
 		start_time=time.time()

                 logger.info("Starting to work on step %s" % step.__name__)

 		dependency_graph = self.dependency_graph if not deletion else self.deletion_dependency_graph

 		# Wait for step dependencies to be met
 		try:
 			deps = self.dependency_graph[S]
 			has_deps = True
 		except KeyError:
 			has_deps = False

 		go = True

                 failed_dep = None
 		if (has_deps):
 			for d in deps:
                                 if d==step.__name__:
                                     logger.info("   step %s self-wait skipped" % step.__name__)
 				    go = True
                                     continue

 				cond = self.step_conditions[d]
 				cond.acquire()
 				if (self.step_status[d] is STEP_STATUS_WORKING):
                                         logger.info("  step %s wait on dep %s" % (step.__name__, d))
 					cond.wait()
 				elif self.step_status[d] == STEP_STATUS_OK:
 					go = True
 				else:
 					go = False
                         		failed_dep = d
 				cond.release()
 				if (not go):
 					break
 		else:
 			go = True

 		if (not go):
                         print bcolors.FAIL + "Step %r skipped on %r" % (step,failed_dep) + bcolors.ENDC
                         # SMBAKER: sync_step was not defined here, so I changed
                         #    this from 'sync_step' to 'step'. Verify.
 			self.failed_steps.append(step)
 			my_status = STEP_STATUS_KO
 		else:
 			sync_step = step(driver=self.driver,error_map=self.error_mapper)
 			sync_step. __name__= step.__name__
 			sync_step.dependencies = []
 			try:
 				mlist = sync_step.provides

 				for m in mlist:
 				        lst =  self.model_dependency_graph[m.__name__]
 			                nlst = map(lambda(a,b):b,lst)
 					sync_step.dependencies.extend(nlst)
 			except KeyError:
 				pass
 			sync_step.debug_mode = debug_mode

 			should_run = False
 			try:
 				# Various checks that decide whether
 				# this step runs or not
 				self.check_class_dependency(sync_step, self.failed_steps) # dont run Slices if Sites failed
 				self.check_schedule(sync_step, deletion) # dont run sync_network_routes if time since last run < 1 hour
 				should_run = True
 			except StepNotReady:
 				logger.info('Step not ready: %s'%sync_step.__name__)
 				self.failed_steps.append(sync_step)
 				my_status = STEP_STATUS_KO
 			except Exception,e:
 				logger.error('%r' % e)
 				logger.log_exc("sync step failed: %r. Deletion: %r"%(sync_step,deletion))
 				self.failed_steps.append(sync_step)
 				my_status = STEP_STATUS_KO

 			if (should_run):
 				try:
 					duration=time.time() - start_time

 					logger.info('Executing step %s' % sync_step.__name__)

 					print bcolors.OKBLUE + "Executing step %s" % sync_step.__name__ + bcolors.ENDC
 					failed_objects = sync_step(failed=list(self.failed_step_objects), deletion=deletion)

 					self.check_duration(sync_step, duration)

 					if failed_objects:
 						self.failed_step_objects.update(failed_objects)

                                         logger.info("Step %r succeeded" % step)
                                         print bcolors.OKGREEN + "Step %r succeeded" % step + bcolors.ENDC
 					my_status = STEP_STATUS_OK
 					self.update_run_time(sync_step,deletion)
 				except Exception,e:
                         		print bcolors.FAIL + "Model step %r failed" % (step) + bcolors.ENDC
 					logger.error('Model step %r failed. This seems like a misconfiguration or bug: %r. This error will not be relayed to the user!' % (step, e))
 					logger.log_exc(e)
 					self.failed_steps.append(S)
 					my_status = STEP_STATUS_KO
 			else:
                                 logger.info("Step %r succeeded due to non-run" % step)
 				my_status = STEP_STATUS_OK

 		try:
 			my_cond = self.step_conditions[S]
 			my_cond.acquire()
 			self.step_status[S]=my_status
 			my_cond.notify_all()
 			my_cond.release()
 		except KeyError,e:
 			logger.info('Step %r is a leaf' % step)
 			pass
             finally:
                 connection.close()

 	def run(self):
 		if not self.driver.enabled:
 			return

 		if (self.driver_kind=="openstack") and (not self.driver.has_openstack):
 			return

 		while True:
 			try:
 				loop_start = time.time()
 				error_map_file = getattr(Config(), "error_map_path", XOS_DIR + "/error_map.txt")
 				self.error_mapper = ErrorMapper(error_map_file)

 				# Set of whole steps that failed
 				self.failed_steps = []

 				# Set of individual objects within steps that failed
 				self.failed_step_objects = set()

 				# Set up conditions and step status
 				# This is needed for steps to run in parallel
 				# while obeying dependencies.

 				providers = set()
 				for v in self.dependency_graph.values():
 					if (v):
 						providers.update(v)

 				self.step_conditions = {}
 				self.step_status = {}
 				for p in list(providers):
 					self.step_conditions[p] = threading.Condition()
 					self.step_status[p] = STEP_STATUS_WORKING


 				logger.info('Waiting for event')
 				tBeforeWait = time.time()
 				self.wait_for_event(timeout=30)
 				logger.info('Observer woke up')

 				# Two passes. One for sync, the other for deletion.
 				for deletion in [False,True]:
 					threads = []
 					logger.info('Deletion=%r...'%deletion)
 					schedule = self.ordered_steps if not deletion else reversed(self.ordered_steps)

 					for S in schedule:
 						thread = threading.Thread(target=self.sync, args=(S, deletion))

 						logger.info('Deletion=%r...'%deletion)
 						threads.append(thread)

 					# Start threads
 					for t in threads:
 						t.start()

 					# Wait for all threads to finish before continuing with the run loop
 					for t in threads:
 						t.join()

 				self.save_run_times()
 				loop_end = time.time()
 				open('/tmp/observer_last_run','w').write(json.dumps({'last_run': loop_end, 'last_duration':loop_end - loop_start}))
 			except Exception, e:
 				logger.error('Core error. This seems like a misconfiguration or bug: %r. This error will not be relayed to the user!' % e)
 				logger.log_exc("Exception in observer run loop")
 				traceback.print_exc()
	import os
	import imp
	import inspect
	import time
	import sys
	import traceback
	import commands
	import threading
	import json
	import pdb
	import pprint


	from datetime import datetime
	from collections import defaultdict
	from core.models import *
	from django.db.models import F, Q
	from django.db import connection
	#from openstack.manager import OpenStackManager
	from openstack.driver import OpenStackDriver
	from util.logger import Logger, logging, logger
	#from timeout import timeout
	from xos.config import Config, XOS_DIR
	from observer.steps import *
	from syncstep import SyncStep
	from toposort import toposort
	from observer.error_mapper import *
	from openstack_observer.openstacksyncstep import OpenStackSyncStep


	debug_mode = False

	class bcolors:
	HEADER = '\033[95m'
	OKBLUE = '\033[94m'
	OKGREEN = '\033[92m'
	WARNING = '\033[93m'
	FAIL = '\033[91m'
	ENDC = '\033[0m'
	BOLD = '\033[1m'
	UNDERLINE = '\033[4m'

	logger = Logger(level=logging.INFO)

	class StepNotReady(Exception):
	pass

	class NoOpDriver:
	def __init__(self):
	self.enabled = True
	self.dependency_graph = None

	STEP_STATUS_WORKING=1
	STEP_STATUS_OK=2
	STEP_STATUS_KO=3

	def invert_graph(g):
	ig = {}
	for k,v in g.items():
	for v0 in v:
	try:
	ig[v0].append(k)
	except:
	ig=[k]
	return ig

	class XOSObserver:
	#sync_steps = [SyncNetworks,SyncNetworkSlivers,SyncSites,SyncSitePrivilege,SyncSlices,SyncSliceMemberships,SyncSlivers,SyncSliverIps,SyncExternalRoutes,SyncUsers,SyncRoles,SyncNodes,SyncImages,GarbageCollector]
	sync_steps = []


	def __init__(self):
	# The Condition object that gets signalled by Feefie events
	self.step_lookup = {}
	self.load_sync_step_modules()
	self.load_sync_steps()
	self.event_cond = threading.Condition()

	self.driver_kind = getattr(Config(), "observer_driver", "openstack")
	if self.driver_kind=="openstack":
	self.driver = OpenStackDriver()
	else:
	self.driver = NoOpDriver()

	def wait_for_event(self, timeout):
	self.event_cond.acquire()
	self.event_cond.wait(timeout)
	self.event_cond.release()

	def wake_up(self):
	logger.info('Wake up routine called. Event cond %r'%self.event_cond)
	self.event_cond.acquire()
	self.event_cond.notify()
	self.event_cond.release()

	def load_sync_step_modules(self, step_dir=None):
	if step_dir is None:
	if hasattr(Config(), "observer_steps_dir"):
	step_dir = Config().observer_steps_dir
	else:
	step_dir = XOS_DIR + "/observer/steps"

	for fn in os.listdir(step_dir):
	pathname = os.path.join(step_dir,fn)
	if os.path.isfile(pathname) and fn.endswith(".py") and (fn!="__init__.py"):
	module = imp.load_source(fn[:-3],pathname)
	for classname in dir(module):
	c = getattr(module, classname, None)

	# make sure 'c' is a descendent of SyncStep and has a
	# provides field (this eliminates the abstract base classes
	# since they don't have a provides)

	if inspect.isclass(c) and (issubclass(c, SyncStep) or issubclass(c,OpenStackSyncStep)) and hasattr(c,"provides") and (c not in self.sync_steps):
	self.sync_steps.append(c)
	logger.info('loaded sync steps: %s' % ",".join([x.__name__ for x in self.sync_steps]))
	# print 'loaded sync steps: %s' % ",".join([x.__name__ for x in self.sync_steps])

	def load_sync_steps(self):
	dep_path = Config().observer_dependency_graph
	logger.info('Loading model dependency graph from %s' % dep_path)
	try:
	# This contains dependencies between records, not sync steps
	self.model_dependency_graph = json.loads(open(dep_path).read())
	for left,lst in self.model_dependency_graph.items():
	new_lst = []
	for k in lst:
	try:
	tup = (k,k.lower())
	new_lst.append(tup)
	deps = self.model_dependency_graph[k]
	except:
	self.model_dependency_graph[k] = []

	self.model_dependency_graph[left] = new_lst
	except Exception,e:
	raise e

	try:
	backend_path = Config().observer_pl_dependency_graph
	logger.info('Loading backend dependency graph from %s' % backend_path)
	# This contains dependencies between backend records
	self.backend_dependency_graph = json.loads(open(backend_path).read())
	for k,v in self.backend_dependency_graph.items():
	try:
	self.model_dependency_graph[k].extend(v)
	except KeyError:
	self.model_dependency_graphp[k] = v

	except Exception,e:
	logger.info('Backend dependency graph not loaded')
	# We can work without a backend graph
	self.backend_dependency_graph = {}

	provides_dict = {}
	for s in self.sync_steps:
	self.step_lookup[s.__name__] = s
	for m in s.provides:
	try:
	provides_dict[m.__name__].append(s.__name__)
	except KeyError:
	provides_dict[m.__name__]=[s.__name__]

	step_graph = {}
	for k,v in self.model_dependency_graph.items():
	try:
	for source in provides_dict[k]:
	if (not v):
	step_graph[source] = []

	for m,_ in v:
	try:
	for dest in provides_dict[m]:
	# no deps, pass
	try:
	if (dest not in step_graph[source]):
	step_graph[source].append(dest)
	except:
	step_graph[source]=[dest]
	except KeyError:
	pass

	except KeyError:
	pass
	# no dependencies, pass


	self.dependency_graph = step_graph
	self.deletion_dependency_graph = invert_graph(step_graph)

	pp = pprint.PrettyPrinter(indent=4)
	pp.pprint(step_graph)
	self.ordered_steps = toposort(self.dependency_graph, map(lambda s:s.__name__,self.sync_steps))
	#self.ordered_steps = ['SyncRoles', 'SyncControllerSites', 'SyncControllerSitePrivileges','SyncImages', 'SyncControllerImages','SyncControllerUsers','SyncControllerUserSitePrivileges','SyncControllerSlices', 'SyncControllerSlicePrivileges', 'SyncControllerUserSlicePrivileges', 'SyncControllerNetworks','SyncSlivers']
	#self.ordered_steps = ['SyncControllerSites','SyncControllerUsers','SyncControllerSlices','SyncControllerNetworks']

	print "Order of steps=",self.ordered_steps

	self.load_run_times()


	def check_duration(self, step, duration):
	try:
	if (duration > step.deadline):
	logger.info('Sync step %s missed deadline, took %.2f seconds'%(step.name,duration))
	except AttributeError:
	# S doesn't have a deadline
	pass

	def update_run_time(self, step, deletion):
	if (not deletion):
	self.last_run_times[step.__name__]=time.time()
	else:
	self.last_deletion_run_times[step.__name__]=time.time()


	def check_schedule(self, step, deletion):
	last_run_times = self.last_run_times if not deletion else self.last_deletion_run_times

	time_since_last_run = time.time() - last_run_times.get(step.__name__, 0)
	try:
	if (time_since_last_run < step.requested_interval):
	raise StepNotReady
	except AttributeError:
	logger.info('Step %s does not have requested_interval set'%step.__name__)
	raise StepNotReady

	def load_run_times(self):
	try:
	jrun_times = open('/tmp/observer_run_times').read()
	self.last_run_times = json.loads(jrun_times)
	except:
	self.last_run_times={}
	for e in self.ordered_steps:
	self.last_run_times[e]=0
	try:
	jrun_times = open('/tmp/observer_deletion_run_times').read()
	self.last_deletion_run_times = json.loads(jrun_times)
	except:
	self.last_deletion_run_times={}
	for e in self.ordered_steps:
	self.last_deletion_run_times[e]=0


	def save_run_times(self):
	run_times = json.dumps(self.last_run_times)
	open('/tmp/observer_run_times','w').write(run_times)

	deletion_run_times = json.dumps(self.last_deletion_run_times)
	open('/tmp/observer_deletion_run_times','w').write(deletion_run_times)

	def check_class_dependency(self, step, failed_steps):
	step.dependenices = []
	for obj in step.provides:
	lst = self.model_dependency_graph.get(obj.__name__, [])
	nlst = map(lambda(a,b):b,lst)
	step.dependenices.extend(nlst)
	for failed_step in failed_steps:
	if (failed_step in step.dependencies):
	raise StepNotReady

	def sync(self, S, deletion):
	try:
	step = self.step_lookup[S]
	start_time=time.time()

	logger.info("Starting to work on step %s" % step.__name__)

	dependency_graph = self.dependency_graph if not deletion else self.deletion_dependency_graph

	# Wait for step dependencies to be met
	try:
	deps = self.dependency_graph[S]
	has_deps = True
	except KeyError:
	has_deps = False

	go = True

	failed_dep = None
	if (has_deps):
	for d in deps:
	if d==step.__name__:
	logger.info(" step %s self-wait skipped" % step.__name__)
	go = True
	continue

	cond = self.step_conditions[d]
	cond.acquire()
	if (self.step_status[d] is STEP_STATUS_WORKING):
	logger.info(" step %s wait on dep %s" % (step.__name__, d))
	cond.wait()
	elif self.step_status[d] == STEP_STATUS_OK:
	go = True
	else:
	go = False
	failed_dep = d
	cond.release()
	if (not go):
	break
	else:
	go = True

	if (not go):
	print bcolors.FAIL + "Step %r skipped on %r" % (step,failed_dep) + bcolors.ENDC
	# SMBAKER: sync_step was not defined here, so I changed
	# this from 'sync_step' to 'step'. Verify.
	self.failed_steps.append(step)
	my_status = STEP_STATUS_KO
	else:
	sync_step = step(driver=self.driver,error_map=self.error_mapper)
	sync_step. __name__= step.__name__
	sync_step.dependencies = []
	try:
	mlist = sync_step.provides

	for m in mlist:
	lst = self.model_dependency_graph[m.__name__]
	nlst = map(lambda(a,b):b,lst)
	sync_step.dependencies.extend(nlst)
	except KeyError:
	pass
	sync_step.debug_mode = debug_mode

	should_run = False
	try:
	# Various checks that decide whether
	# this step runs or not
	self.check_class_dependency(sync_step, self.failed_steps) # dont run Slices if Sites failed
	self.check_schedule(sync_step, deletion) # dont run sync_network_routes if time since last run < 1 hour
	should_run = True
	except StepNotReady:
	logger.info('Step not ready: %s'%sync_step.__name__)
	self.failed_steps.append(sync_step)
	my_status = STEP_STATUS_KO
	except Exception,e:
	logger.error('%r' % e)
	logger.log_exc("sync step failed: %r. Deletion: %r"%(sync_step,deletion))
	self.failed_steps.append(sync_step)
	my_status = STEP_STATUS_KO

	if (should_run):
	try:
	duration=time.time() - start_time

	logger.info('Executing step %s' % sync_step.__name__)

	print bcolors.OKBLUE + "Executing step %s" % sync_step.__name__ + bcolors.ENDC
	failed_objects = sync_step(failed=list(self.failed_step_objects), deletion=deletion)

	self.check_duration(sync_step, duration)

	if failed_objects:
	self.failed_step_objects.update(failed_objects)

	logger.info("Step %r succeeded" % step)
	print bcolors.OKGREEN + "Step %r succeeded" % step + bcolors.ENDC
	my_status = STEP_STATUS_OK
	self.update_run_time(sync_step,deletion)
	except Exception,e:
	print bcolors.FAIL + "Model step %r failed" % (step) + bcolors.ENDC
	logger.error('Model step %r failed. This seems like a misconfiguration or bug: %r. This error will not be relayed to the user!' % (step, e))
	logger.log_exc(e)
	self.failed_steps.append(S)
	my_status = STEP_STATUS_KO
	else:
	logger.info("Step %r succeeded due to non-run" % step)
	my_status = STEP_STATUS_OK

	try:
	my_cond = self.step_conditions[S]
	my_cond.acquire()
	self.step_status[S]=my_status
	my_cond.notify_all()
	my_cond.release()
	except KeyError,e:
	logger.info('Step %r is a leaf' % step)
	pass
	finally:
	connection.close()

	def run(self):
	if not self.driver.enabled:
	return

	if (self.driver_kind=="openstack") and (not self.driver.has_openstack):
	return

	while True:
	try:
	loop_start = time.time()
	error_map_file = getattr(Config(), "error_map_path", XOS_DIR + "/error_map.txt")
	self.error_mapper = ErrorMapper(error_map_file)

	# Set of whole steps that failed
	self.failed_steps = []

	# Set of individual objects within steps that failed
	self.failed_step_objects = set()

	# Set up conditions and step status
	# This is needed for steps to run in parallel
	# while obeying dependencies.

	providers = set()
	for v in self.dependency_graph.values():
	if (v):
	providers.update(v)

	self.step_conditions = {}
	self.step_status = {}
	for p in list(providers):
	self.step_conditions[p] = threading.Condition()
	self.step_status[p] = STEP_STATUS_WORKING


	logger.info('Waiting for event')
	tBeforeWait = time.time()
	self.wait_for_event(timeout=30)
	logger.info('Observer woke up')

	# Two passes. One for sync, the other for deletion.
	for deletion in [False,True]:
	threads = []
	logger.info('Deletion=%r...'%deletion)
	schedule = self.ordered_steps if not deletion else reversed(self.ordered_steps)

	for S in schedule:
	thread = threading.Thread(target=self.sync, args=(S, deletion))

	logger.info('Deletion=%r...'%deletion)
	threads.append(thread)

	# Start threads
	for t in threads:
	t.start()

	# Wait for all threads to finish before continuing with the run loop
	for t in threads:
	t.join()

	self.save_run_times()
	loop_end = time.time()
	open('/tmp/observer_last_run','w').write(json.dumps({'last_run': loop_end, 'last_duration':loop_end - loop_start}))
	except Exception, e:
	logger.error('Core error. This seems like a misconfiguration or bug: %r. This error will not be relayed to the user!' % e)
	logger.log_exc("Exception in observer run loop")
	traceback.print_exc()