def main():
zk = ZooKeeper()
zk.start_session(expire=60)
if not zk.exists('/queue'):
zk.create('/queue')
q = Queue('/queue', zk)
print 'Pushing to queue 1 ... 5'
map(q.put, [1,2,3,4,5])
print 'Extracting ...'
while True:
el = q.fetch()
if el is None:
break
print el
zk.close_session()
zk.delete('/queue')
print 'Done.'
def main():
zk = ZooKeeper()
# create the root node used for master election
if not zk.exists('/election'):
zk.create('/election')
print 'Starting 10 agents ...'
agents = [Agent(id) for id in range(0, 15)]
map(Agent.start, agents)
map(Agent.join, agents)
zk.delete('/election')
class Agent(threading.Thread):
""" A basic agent that wants to become a master and exit """
root = '/election'
def __init__(self, id):
super(Agent, self).__init__()
self.zk = ZooKeeper()
self.id = id
def run(self):
print 'Starting #%s' % self.id
with self.zk.session(expire=5):
# signal agent presence
r = self.zk.create("%s/agent-" % self.root,
sequence=True,
ephemeral=True)
self.me = r['path']
while True:
children = sorted([el['path'] \
for el in self.zk.get_children(self.root)])
master, previous = children[0], None
try:
index = children.index(self.me)
if index != 0:
previous = children[index - 1]
except ValueError:
break
if previous is None:
self.do_master_work()
# and don't forget to send heartbeat messages
break
else:
# do slave work in another thread
pass
# wait for the previous agent or current master to exit / finish
while self.zk.exists(previous) or self.zk.exists(master):
time.sleep(0.5)
self.zk.heartbeat()
# TODO signal the slave thread to exit and wait for it
# and rerun the election loop
def do_master_work(self):
print "#%s: I'm the master: %s" % (self.id, self.me)
class Agent(threading.Thread):
""" A basic agent that wants to become a master and exit """
root = '/election'
def __init__(self, id):
super(Agent, self).__init__()
self.zk = ZooKeeper()
self.id = id
def run(self):
print 'Starting #%s' % self.id
with self.zk.session(expire=5):
# signal agent presence
r = self.zk.create("%s/agent-" % self.root,
sequence=True, ephemeral=True)
self.me = r['path']
while True:
children = sorted([el['path'] \
for el in self.zk.get_children(self.root)])
master, previous = children[0], None
try:
index = children.index(self.me)
if index != 0:
previous = children[index-1]
except ValueError:
break
if previous is None:
self.do_master_work()
# and don't forget to send heartbeat messages
break
else:
# do slave work in another thread
pass
# wait for the previous agent or current master to exit / finish
while self.zk.exists(previous) or self.zk.exists(master):
time.sleep(0.5)
self.zk.heartbeat()
# TODO signal the slave thread to exit and wait for it
# and rerun the election loop
def do_master_work(self):
print "#%s: I'm the master: %s" % (self.id, self.me)
def main():
zk = ZooKeeper()
# create the root node used for master election
if not zk.exists('/election'):
zk.create('/election')
print 'Starting 10 agents ...'
agents = [Agent(id) for id in range(0,15)]
map(Agent.start, agents)
map(Agent.join, agents)
zk.delete('/election')
def __init__(self, id):
super(Agent, self).__init__()
self.zk = ZooKeeper()
self.id = id
def main():
zk = ZooKeeper()
zk.start_session(expire=60)
if not zk.exists('/queue'):
zk.create('/queue')
q = Queue('/queue', zk)
print 'Pushing to queue 1 ... 5'
map(q.put, [1, 2, 3, 4, 5])
print 'Extracting ...'
while True:
el = q.fetch()
if el is None:
break
print el
zk.close_session()
zk.delete('/queue')
print 'Done.'
def __init__(self, id):
super(Agent, self).__init__()
self.zk = ZooKeeper()
self.id = id
def setUp(self):
self.zk = ZooKeeper(self.BASE_URI)
class ZooKeeperREST_TestCase(unittest.TestCase):
BASE_URI = 'http://localhost:9998'
def setUp(self):
self.zk = ZooKeeper(self.BASE_URI)
def tearDown(self):
try:
self.zk.delete('/test')
except ZooKeeper.NotFound:
pass
def test_get_root_node(self):
assert self.zk.get('/') is not None
def test_get_node_not_found(self):
self.assertRaises(ZooKeeper.NotFound, \
self.zk.get, '/dummy-node')
def test_exists_node(self):
assert self.zk.exists('/zookeeper') is True
def test_get_children(self):
assert any([child['path'] == '/zookeeper/quota' \
for child in self.zk.get_children('/zookeeper')])
def test_create_znode(self):
try:
self.zk.create('/test')
except ZooKeeper.ZNodeExists:
pass # it's ok if already exists
assert self.zk.exists('/test') is True
def test_create_hierarchy(self):
try:
self.zk.delete(['/a/b', '/a'])
except ZooKeeper.NotFound:
pass
self.zk.create('/a')
self.zk.create('/a/b')
self.zk.delete(['/a/b', '/a'])
def test_create_with_data(self):
self.zk.create('/test', 'some-data')
zn = self.zk.get('/test')
self.assertEqual(zn.get('data64', None), \
'some-data'.encode('base64').strip())
def test_delete_znode(self):
self.zk.create('/test')
self.zk.delete('/test')
assert not self.zk.exists('/test')
def test_delete_older_version(self):
self.zk.create('/test')
zn = self.zk.get('/test')
# do one more modification in order to increase the version number
self.zk.set('/test', 'dummy-data')
self.assertRaises(ZooKeeper.WrongVersion, \
self.zk.delete, '/test', version=zn['version'])
def test_delete_raise_not_found(self):
self.zk.create('/test')
zn = self.zk.get('/test')
self.zk.delete('/test')
self.assertRaises(ZooKeeper.NotFound, \
self.zk.delete, '/test', version=zn['version'])
def test_set(self):
self.zk.create('/test')
self.zk.set('/test', 'dummy')
self.assertEqual(self.zk.get('/test')['data64'], \
'dummy'.encode('base64').strip())
def test_set_with_older_version(self):
if not self.zk.exists('/test'):
self.zk.create('/test', 'random-data')
zn = self.zk.get('/test')
self.zk.set('/test', 'new-data')
self.assertRaises(ZooKeeper.WrongVersion, self.zk.set, \
'/test', 'older-version', version=zn['version'])
def test_set_null(self):
if not self.zk.exists('/test'):
self.zk.create('/test', 'random-data')
self.zk.set('/test', 'data')
assert 'data64' in self.zk.get('/test')
self.zk.set('/test', null=True)
assert 'data64' not in self.zk.get('/test')
def test_create_ephemeral_node(self):
with self.zk.session():
if self.zk.exists('/ephemeral-test'):
self.zk.delete('/ephemeral-test')
self.zk.create('/ephemeral-test', ephemeral=True)
zn = self.zk.get('/ephemeral-test')
assert zn['ephemeralOwner'] != 0
def test_create_session(self):
with self.zk.session() as sid:
self.assertEqual(len(sid), 36) # UUID
def test_session_invalidation(self):
self.zk.start_session(expire=1)
self.zk.create('/ephemeral-test', ephemeral=True)
# keep the session alive by sending heartbeat requests
for _ in range(1,2):
self.zk.heartbeat()
time.sleep(0.9)
time.sleep(2) # wait for the session to expire
self.assertRaises(ZooKeeper.InvalidSession, \
self.zk.create, '/ephemeral-test', ephemeral=True)
def test_presence_signaling(self):
with self.zk.session(expire=1):
self.zk.create('/i-am-online', ephemeral=True)
assert self.zk.exists('/i-am-online')
assert not self.zk.exists('/i-am-online')