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-rw-r--r--doc/source/dev/architecture.rst2
-rw-r--r--ironic/common/hash_ring.py114
-rw-r--r--ironic/conductor/base_manager.py8
-rw-r--r--ironic/conductor/manager.py11
-rw-r--r--ironic/conductor/rpcapi.py10
-rw-r--r--ironic/tests/unit/common/test_hash_ring.py190
-rw-r--r--releasenotes/notes/add-tooz-dep-85c56c74733a222d.yaml6
-rw-r--r--requirements.txt1
8 files changed, 29 insertions, 313 deletions
diff --git a/doc/source/dev/architecture.rst b/doc/source/dev/architecture.rst
index 7aa6bd574..75bf7d4e7 100644
--- a/doc/source/dev/architecture.rst
+++ b/doc/source/dev/architecture.rst
@@ -122,5 +122,5 @@ driver actions such as take-over or clean-up.
.. _Conductor service: ../api/ironic.conductor.manager.html
.. _DB API: ../api/ironic.db.api.html
.. _diskimage-builder: http://docs.openstack.org/developer/diskimage-builder/
-.. _consistent hashing algorithm: ../api/ironic.common.hash_ring.html
+.. _consistent hashing algorithm: http://docs.openstack.org/developer/tooz/tutorial/hashring.html
.. _periodic: http://docs.openstack.org/developer/futurist/api.html#futurist.periodics.periodic
diff --git a/ironic/common/hash_ring.py b/ironic/common/hash_ring.py
index bf58a1cda..95cfbdef3 100644
--- a/ironic/common/hash_ring.py
+++ b/ironic/common/hash_ring.py
@@ -13,12 +13,10 @@
# License for the specific language governing permissions and limitations
# under the License.
-import bisect
-import hashlib
import threading
import time
-import six
+from tooz import hashring
from ironic.common import exception
from ironic.common.i18n import _
@@ -26,113 +24,6 @@ from ironic.conf import CONF
from ironic.db import api as dbapi
-class HashRing(object):
- """A stable hash ring.
-
- We map item N to a host Y based on the closest lower hash:
-
- - hash(item) -> partition
- - hash(host) -> divider
- - closest lower divider is the host to use
- - we hash each host many times to spread load more finely
- as otherwise adding a host gets (on average) 50% of the load of
- just one other host assigned to it.
- """
-
- def __init__(self, hosts, replicas=None):
- """Create a new hash ring across the specified hosts.
-
- :param hosts: an iterable of hosts which will be mapped.
- :param replicas: number of hosts to map to each hash partition,
- or len(hosts), which ever is lesser.
- Default: CONF.hash_distribution_replicas
-
- """
- if replicas is None:
- replicas = CONF.hash_distribution_replicas
-
- try:
- self.hosts = set(hosts)
- self.replicas = replicas if replicas <= len(hosts) else len(hosts)
- except TypeError:
- raise exception.Invalid(
- _("Invalid hosts supplied when building HashRing."))
-
- self._host_hashes = {}
- for host in hosts:
- key = str(host).encode('utf8')
- key_hash = hashlib.md5(key)
- for p in range(2 ** CONF.hash_partition_exponent):
- key_hash.update(key)
- hashed_key = self._hash2int(key_hash)
- self._host_hashes[hashed_key] = host
- # Gather the (possibly colliding) resulting hashes into a bisectable
- # list.
- self._partitions = sorted(self._host_hashes.keys())
-
- def _hash2int(self, key_hash):
- """Convert the given hash's digest to a numerical value for the ring.
-
- :returns: An integer equivalent value of the digest.
- """
- return int(key_hash.hexdigest(), 16)
-
- def _get_partition(self, data):
- try:
- if six.PY3 and data is not None:
- data = data.encode('utf-8')
- key_hash = hashlib.md5(data)
- hashed_key = self._hash2int(key_hash)
- position = bisect.bisect(self._partitions, hashed_key)
- return position if position < len(self._partitions) else 0
- except TypeError:
- raise exception.Invalid(
- _("Invalid data supplied to HashRing.get_hosts."))
-
- def get_hosts(self, data, ignore_hosts=None):
- """Get the list of hosts which the supplied data maps onto.
-
- :param data: A string identifier to be mapped across the ring.
- :param ignore_hosts: A list of hosts to skip when performing the hash.
- Useful to temporarily skip down hosts without
- performing a full rebalance.
- Default: None.
- :returns: a list of hosts.
- The length of this list depends on the number of replicas
- this `HashRing` was created with. It may be less than this
- if ignore_hosts is not None.
- """
- hosts = []
- if ignore_hosts is None:
- ignore_hosts = set()
- else:
- ignore_hosts = set(ignore_hosts)
- ignore_hosts.intersection_update(self.hosts)
- partition = self._get_partition(data)
- for replica in range(0, self.replicas):
- if len(hosts) + len(ignore_hosts) == len(self.hosts):
- # prevent infinite loop - cannot allocate more fallbacks.
- break
- # Linear probing: partition N, then N+1 etc.
- host = self._get_host(partition)
- while host in hosts or host in ignore_hosts:
- partition += 1
- if partition >= len(self._partitions):
- partition = 0
- host = self._get_host(partition)
- hosts.append(host)
- return hosts
-
- def _get_host(self, partition):
- """Find what host is serving a partition.
-
- :param partition: The index of the partition in the partition map.
- e.g. 0 is the first partition, 1 is the second.
- :return: The host object the ring was constructed with.
- """
- return self._host_hashes[self._partitions[partition]]
-
-
class HashRingManager(object):
_hash_rings = None
_lock = threading.Lock()
@@ -161,7 +52,8 @@ class HashRingManager(object):
d2c = self.dbapi.get_active_driver_dict()
for driver_name, hosts in d2c.items():
- rings[driver_name] = HashRing(hosts)
+ rings[driver_name] = hashring.HashRing(
+ hosts, partitions=2 ** CONF.hash_partition_exponent)
return rings
@classmethod
diff --git a/ironic/conductor/base_manager.py b/ironic/conductor/base_manager.py
index e3a2edc21..6c88708ba 100644
--- a/ironic/conductor/base_manager.py
+++ b/ironic/conductor/base_manager.py
@@ -26,7 +26,7 @@ from oslo_utils import excutils
from ironic.common import context as ironic_context
from ironic.common import driver_factory
from ironic.common import exception
-from ironic.common import hash_ring as hash
+from ironic.common import hash_ring
from ironic.common.i18n import _, _LC, _LE, _LI, _LW
from ironic.common import rpc
from ironic.common import states
@@ -78,7 +78,7 @@ class BaseConductorManager(object):
check_and_reject=rejection_func)
"""Executor for performing tasks async."""
- self.ring_manager = hash.HashRingManager()
+ self.ring_manager = hash_ring.HashRingManager()
"""Consistent hash ring which maps drivers to conductors."""
# NOTE(deva): these calls may raise DriverLoadError or DriverNotFound
@@ -302,7 +302,9 @@ class BaseConductorManager(object):
except exception.DriverNotFound:
return False
- return self.host in ring.get_hosts(node_uuid)
+ return self.host in ring.get_nodes(
+ node_uuid.encode('utf-8'),
+ replicas=CONF.hash_distribution_replicas)
def _fail_if_in_state(self, context, filters, provision_state,
sort_key, callback_method=None,
diff --git a/ironic/conductor/manager.py b/ironic/conductor/manager.py
index 9161ef718..ba312d6f2 100644
--- a/ironic/conductor/manager.py
+++ b/ironic/conductor/manager.py
@@ -34,11 +34,12 @@ locked by each conductor when performing actions which change the state of that
node; these locks are represented by the
:py:class:`ironic.conductor.task_manager.TaskManager` class.
-A :py:class:`ironic.common.hash_ring.HashRing` is used to distribute nodes
-across the set of active conductors which support each node's driver.
-Rebalancing this ring can trigger various actions by each conductor, such as
-building or tearing down the TFTP environment for a node, notifying Neutron of
-a change, etc.
+A `tooz.hashring.HashRing
+<https://git.openstack.org/cgit/openstack/tooz/tree/tooz/hashring.py>`_
+is used to distribute nodes across the set of active conductors which support
+each node's driver. Rebalancing this ring can trigger various actions by each
+conductor, such as building or tearing down the TFTP environment for a node,
+notifying Neutron of a change, etc.
"""
import collections
diff --git a/ironic/conductor/rpcapi.py b/ironic/conductor/rpcapi.py
index d6d433edf..7cf53e518 100644
--- a/ironic/conductor/rpcapi.py
+++ b/ironic/conductor/rpcapi.py
@@ -27,6 +27,7 @@ from ironic.common import hash_ring
from ironic.common.i18n import _
from ironic.common import rpc
from ironic.conductor import manager
+from ironic.conf import CONF
from ironic.objects import base as objects_base
@@ -119,8 +120,9 @@ class ConductorAPI(object):
try:
ring = self.ring_manager[node.driver]
- dest = ring.get_hosts(node.uuid)
- return self.topic + "." + dest[0]
+ dest = ring.get_nodes(node.uuid.encode('utf-8'),
+ replicas=CONF.hash_distribution_replicas)
+ return '%s.%s' % (self.topic, dest.pop())
except exception.DriverNotFound:
reason = (_('No conductor service registered which supports '
'driver %s.') % node.driver)
@@ -140,8 +142,8 @@ class ConductorAPI(object):
"""
self.ring_manager.reset()
- hash_ring = self.ring_manager[driver_name]
- host = random.choice(list(hash_ring.hosts))
+ ring = self.ring_manager[driver_name]
+ host = random.choice(list(ring.nodes))
return self.topic + "." + host
def create_node(self, context, node_obj, topic=None):
diff --git a/ironic/tests/unit/common/test_hash_ring.py b/ironic/tests/unit/common/test_hash_ring.py
index 1966b9e8e..798980fd7 100644
--- a/ironic/tests/unit/common/test_hash_ring.py
+++ b/ironic/tests/unit/common/test_hash_ring.py
@@ -13,205 +13,17 @@
# License for the specific language governing permissions and limitations
# under the License.
-import hashlib
import time
-import mock
from oslo_config import cfg
-from testtools import matchers
from ironic.common import exception
from ironic.common import hash_ring
-from ironic.tests import base
from ironic.tests.unit.db import base as db_base
CONF = cfg.CONF
-class HashRingTestCase(base.TestCase):
-
- # NOTE(deva): the mapping used in these tests is as follows:
- # if hosts = [foo, bar]:
- # fake -> foo, bar
- # if hosts = [foo, bar, baz]:
- # fake -> foo, bar, baz
- # fake-again -> bar, baz, foo
-
- @mock.patch.object(hashlib, 'md5', autospec=True)
- def test__hash2int_returns_int(self, mock_md5):
- CONF.set_override('hash_partition_exponent', 0)
- r1 = 32 * 'a'
- r2 = 32 * 'b'
- mock_md5.return_value.hexdigest.side_effect = [r1, r2]
-
- hosts = ['foo', 'bar']
- replicas = 1
- ring = hash_ring.HashRing(hosts, replicas=replicas)
-
- self.assertIn(int(r1, 16), ring._host_hashes)
- self.assertIn(int(r2, 16), ring._host_hashes)
-
- def test_create_ring(self):
- hosts = ['foo', 'bar']
- replicas = 2
- ring = hash_ring.HashRing(hosts, replicas=replicas)
- self.assertEqual(set(hosts), ring.hosts)
- self.assertEqual(replicas, ring.replicas)
-
- def test_create_with_different_partition_counts(self):
- hosts = ['foo', 'bar']
- CONF.set_override('hash_partition_exponent', 2)
- ring = hash_ring.HashRing(hosts)
- self.assertEqual(2 ** 2 * 2, len(ring._partitions))
-
- CONF.set_override('hash_partition_exponent', 8)
- ring = hash_ring.HashRing(hosts)
- self.assertEqual(2 ** 8 * 2, len(ring._partitions))
-
- CONF.set_override('hash_partition_exponent', 16)
- ring = hash_ring.HashRing(hosts)
- self.assertEqual(2 ** 16 * 2, len(ring._partitions))
-
- def test_distribution_one_replica(self):
- hosts = ['foo', 'bar', 'baz']
- ring = hash_ring.HashRing(hosts, replicas=1)
- fake_1_hosts = ring.get_hosts('fake')
- fake_2_hosts = ring.get_hosts('fake-again')
- # We should have one hosts for each thing
- self.assertThat(fake_1_hosts, matchers.HasLength(1))
- self.assertThat(fake_2_hosts, matchers.HasLength(1))
- # And they must not be the same answers even on this simple data.
- self.assertNotEqual(fake_1_hosts, fake_2_hosts)
-
- def test_distribution_two_replicas(self):
- hosts = ['foo', 'bar', 'baz']
- ring = hash_ring.HashRing(hosts, replicas=2)
- fake_1_hosts = ring.get_hosts('fake')
- fake_2_hosts = ring.get_hosts('fake-again')
- # We should have two hosts for each thing
- self.assertThat(fake_1_hosts, matchers.HasLength(2))
- self.assertThat(fake_2_hosts, matchers.HasLength(2))
- # And they must not be the same answers even on this simple data
- # because if they were we'd be making the active replica a hot spot.
- self.assertNotEqual(fake_1_hosts, fake_2_hosts)
-
- def test_distribution_three_replicas(self):
- hosts = ['foo', 'bar', 'baz']
- ring = hash_ring.HashRing(hosts, replicas=3)
- fake_1_hosts = ring.get_hosts('fake')
- fake_2_hosts = ring.get_hosts('fake-again')
- # We should have two hosts for each thing
- self.assertThat(fake_1_hosts, matchers.HasLength(3))
- self.assertThat(fake_2_hosts, matchers.HasLength(3))
- # And they must not be the same answers even on this simple data
- # because if they were we'd be making the active replica a hot spot.
- self.assertNotEqual(fake_1_hosts, fake_2_hosts)
- self.assertNotEqual(fake_1_hosts[0], fake_2_hosts[0])
-
- def test_ignore_hosts(self):
- hosts = ['foo', 'bar', 'baz']
- ring = hash_ring.HashRing(hosts, replicas=1)
- equals_bar_or_baz = matchers.MatchesAny(
- matchers.Equals(['bar']),
- matchers.Equals(['baz']))
- self.assertThat(
- ring.get_hosts('fake', ignore_hosts=['foo']),
- equals_bar_or_baz)
- self.assertThat(
- ring.get_hosts('fake', ignore_hosts=['foo', 'bar']),
- equals_bar_or_baz)
- self.assertEqual([], ring.get_hosts('fake', ignore_hosts=hosts))
-
- def test_ignore_hosts_with_replicas(self):
- hosts = ['foo', 'bar', 'baz']
- ring = hash_ring.HashRing(hosts, replicas=2)
- self.assertEqual(
- set(['bar', 'baz']),
- set(ring.get_hosts('fake', ignore_hosts=['foo'])))
- self.assertEqual(
- set(['baz']),
- set(ring.get_hosts('fake', ignore_hosts=['foo', 'bar'])))
- self.assertEqual(
- set(['baz', 'foo']),
- set(ring.get_hosts('fake-again', ignore_hosts=['bar'])))
- self.assertEqual(
- set(['foo']),
- set(ring.get_hosts('fake-again', ignore_hosts=['bar', 'baz'])))
- self.assertEqual([], ring.get_hosts('fake', ignore_hosts=hosts))
-
- def _compare_rings(self, nodes, conductors, ring,
- new_conductors, new_ring):
- delta = {}
- mapping = dict((node, ring.get_hosts(node)[0]) for node in nodes)
- new_mapping = dict(
- (node, new_ring.get_hosts(node)[0]) for node in nodes)
-
- for key, old in mapping.items():
- new = new_mapping.get(key, None)
- if new != old:
- delta[key] = (old, new)
- return delta
-
- def test_rebalance_stability_join(self):
- num_conductors = 10
- num_nodes = 10000
- # Adding 1 conductor to a set of N should move 1/(N+1) of all nodes
- # Eg, for a cluster of 10 nodes, adding one should move 1/11, or 9%
- # We allow for 1/N to allow for rounding in tests.
- redistribution_factor = 1.0 / num_conductors
-
- nodes = [str(x) for x in range(num_nodes)]
- conductors = [str(x) for x in range(num_conductors)]
- new_conductors = conductors + ['new']
- delta = self._compare_rings(
- nodes, conductors, hash_ring.HashRing(conductors),
- new_conductors, hash_ring.HashRing(new_conductors))
-
- self.assertLess(len(delta), num_nodes * redistribution_factor)
-
- def test_rebalance_stability_leave(self):
- num_conductors = 10
- num_nodes = 10000
- # Removing 1 conductor from a set of N should move 1/(N) of all nodes
- # Eg, for a cluster of 10 nodes, removing one should move 1/10, or 10%
- # We allow for 1/(N-1) to allow for rounding in tests.
- redistribution_factor = 1.0 / (num_conductors - 1)
-
- nodes = [str(x) for x in range(num_nodes)]
- conductors = [str(x) for x in range(num_conductors)]
- new_conductors = conductors[:]
- new_conductors.pop()
- delta = self._compare_rings(
- nodes, conductors, hash_ring.HashRing(conductors),
- new_conductors, hash_ring.HashRing(new_conductors))
-
- self.assertLess(len(delta), num_nodes * redistribution_factor)
-
- def test_more_replicas_than_hosts(self):
- hosts = ['foo', 'bar']
- ring = hash_ring.HashRing(hosts, replicas=10)
- self.assertEqual(set(hosts), set(ring.get_hosts('fake')))
-
- def test_ignore_non_existent_host(self):
- hosts = ['foo', 'bar']
- ring = hash_ring.HashRing(hosts, replicas=1)
- self.assertEqual(['foo'], ring.get_hosts('fake',
- ignore_hosts=['baz']))
-
- def test_create_ring_invalid_data(self):
- hosts = None
- self.assertRaises(exception.Invalid,
- hash_ring.HashRing,
- hosts)
-
- def test_get_hosts_invalid_data(self):
- hosts = ['foo', 'bar']
- ring = hash_ring.HashRing(hosts)
- self.assertRaises(exception.Invalid,
- ring.get_hosts,
- None)
-
-
class HashRingManagerTestCase(db_base.DbTestCase):
def setUp(self):
@@ -231,7 +43,7 @@ class HashRingManagerTestCase(db_base.DbTestCase):
def test_hash_ring_manager_get_ring_success(self):
self.register_conductors()
ring = self.ring_manager['driver1']
- self.assertEqual(sorted(['host1', 'host2']), sorted(ring.hosts))
+ self.assertEqual(sorted(['host1', 'host2']), sorted(ring.nodes))
def test_hash_ring_manager_driver_not_found(self):
self.register_conductors()
diff --git a/releasenotes/notes/add-tooz-dep-85c56c74733a222d.yaml b/releasenotes/notes/add-tooz-dep-85c56c74733a222d.yaml
new file mode 100644
index 000000000..dc6eb7647
--- /dev/null
+++ b/releasenotes/notes/add-tooz-dep-85c56c74733a222d.yaml
@@ -0,0 +1,6 @@
+---
+upgrade:
+ - |
+ Adds a new dependency on the
+ `tooz library <https://pypi.python.org/pypi/tooz>`_, as the consistent
+ hash ring code was moved out of ironic and into tooz.
diff --git a/requirements.txt b/requirements.txt
index 801a7771e..6aa00dd62 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -41,3 +41,4 @@ oslo.versionedobjects>=1.17.0 # Apache-2.0
jsonschema!=2.5.0,<3.0.0,>=2.0.0 # MIT
psutil<2.0.0,>=1.1.1 # BSD
futurist!=0.15.0,>=0.11.0 # Apache-2.0
+tooz>=1.47.0 # Apache-2.0
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