def test_empty_ring(self):
"""
Assert `get_node()` returns None for all keys
when ServerRing is empty.
"""
hr = ServerRing()
random_word_gen = self._create_random_word_gen()
for i in xrange(10):
path = '/images/%s/%s.png' % (random_word_gen.next(), random_word_gen.next())
server = hr.get_node(path)
self.assertIsNone(server)
def test_consistency(self):
"""
Assert the same node is returned by `get_node()` for a given key.
"""
servers = ('http://asset0.example.com',
'http://asset1.example.com',
'http://asset2.example.com',
'http://asset3.example.com')
hr = ServerRing(servers)
random_word_gen = self._create_random_word_gen()
urls_by_path = dict()
for i in xrange(100):
path = '/images/%s/%s.png' % (random_word_gen.next(), random_word_gen.next())
server = hr.get_node(path)
urls_by_path[path] = ''.join((server, path))
for path in urls_by_path:
url = ''.join((hr.get_node(path), path))
self.assertEqual(urls_by_path[path], url)
def test_remove_node(self):
"""
Assert `get_node()` returns the same node for a given key
when a node is removed.
"""
servers = ('http://asset0.example.com',
'http://asset1.example.com',
'http://asset2.example.com',
'http://asset3.example.com')
hr = ServerRing(servers)
random_word_gen = self._create_random_word_gen()
urls_by_serverpath = dict()
for i in xrange(100):
path = '/images/%s/%s.png' % (random_word_gen.next(), random_word_gen.next())
server = hr.get_node(path)
urls_by_serverpath[(server,path)] = ''.join((server, path))
removed_server = servers[2]
hr.remove_node(removed_server)
for server,path in urls_by_serverpath:
if server == removed_server:
continue
s = hr.get_node(path)
self.assertEqual(server, s)
def test_add_node(self):
"""
Assert `get_node()` returns the same node for a given key
when a node is added.
"""
import collections
servers = ('http://asset0.example.com',
'http://asset1.example.com',
'http://asset3.example.com')
hr = ServerRing(servers)
random_word_gen = self._create_random_word_gen()
urls_by_serverpath = dict()
for i in xrange(100):
path = '/images/%s/%s.png' % (random_word_gen.next(), random_word_gen.next())
server = hr.get_node(path)
urls_by_serverpath[(server,path)] = ''.join((server, path))
# check new server has entries 'rebalanced'
new_server = 'http://asset2.example.com'
hr.add_node(new_server)
counts_by_server = collections.defaultdict(int)
for server,path in urls_by_serverpath:
counts_by_server[hr.get_node(path)] += 1
# assert new node has entries
self.assertTrue(counts_by_server[new_server] > 0)
