Source code for kafka.cluster
from __future__ import absolute_import
import collections
import copy
import logging
import threading
import time
from kafka.vendor import six
from kafka import errors as Errors
from kafka.conn import collect_hosts
from kafka.future import Future
from kafka.structs import BrokerMetadata, PartitionMetadata, TopicPartition
log = logging.getLogger(__name__)
[docs]class ClusterMetadata(object):
"""
A class to manage kafka cluster metadata.
This class does not perform any IO. It simply updates internal state
given API responses (MetadataResponse, GroupCoordinatorResponse).
Keyword Arguments:
retry_backoff_ms (int): Milliseconds to backoff when retrying on
errors. Default: 100.
metadata_max_age_ms (int): The period of time in milliseconds after
which we force a refresh of metadata even if we haven't seen any
partition leadership changes to proactively discover any new
brokers or partitions. Default: 300000
bootstrap_servers: 'host[:port]' string (or list of 'host[:port]'
strings) that the client should contact to bootstrap initial
cluster metadata. This does not have to be the full node list.
It just needs to have at least one broker that will respond to a
Metadata API Request. Default port is 9092. If no servers are
specified, will default to localhost:9092.
"""
DEFAULT_CONFIG = {
'retry_backoff_ms': 100,
'metadata_max_age_ms': 300000,
'bootstrap_servers': [],
}
def __init__(self, **configs):
self._brokers = {} # node_id -> BrokerMetadata
self._partitions = {} # topic -> partition -> PartitionMetadata
self._broker_partitions = collections.defaultdict(set) # node_id -> {TopicPartition...}
self._groups = {} # group_name -> node_id
self._last_refresh_ms = 0
self._last_successful_refresh_ms = 0
self._need_update = True
self._future = None
self._listeners = set()
self._lock = threading.Lock()
self.need_all_topic_metadata = False
self.unauthorized_topics = set()
self.internal_topics = set()
self.controller = None
self.config = copy.copy(self.DEFAULT_CONFIG)
for key in self.config:
if key in configs:
self.config[key] = configs[key]
self._bootstrap_brokers = self._generate_bootstrap_brokers()
self._coordinator_brokers = {}
def _generate_bootstrap_brokers(self):
# collect_hosts does not perform DNS, so we should be fine to re-use
bootstrap_hosts = collect_hosts(self.config['bootstrap_servers'])
brokers = {}
for i, (host, port, _) in enumerate(bootstrap_hosts):
node_id = 'bootstrap-%s' % i
brokers[node_id] = BrokerMetadata(node_id, host, port, None)
return brokers
def is_bootstrap(self, node_id):
return node_id in self._bootstrap_brokers
[docs] def brokers(self):
"""Get all BrokerMetadata
Returns:
set: {BrokerMetadata, ...}
"""
return set(self._brokers.values()) or set(self._bootstrap_brokers.values())
[docs] def broker_metadata(self, broker_id):
"""Get BrokerMetadata
Arguments:
broker_id (int): node_id for a broker to check
Returns:
BrokerMetadata or None if not found
"""
return (
self._brokers.get(broker_id) or
self._bootstrap_brokers.get(broker_id) or
self._coordinator_brokers.get(broker_id)
)
[docs] def partitions_for_topic(self, topic):
"""Return set of all partitions for topic (whether available or not)
Arguments:
topic (str): topic to check for partitions
Returns:
set: {partition (int), ...}
"""
if topic not in self._partitions:
return None
return set(self._partitions[topic].keys())
[docs] def available_partitions_for_topic(self, topic):
"""Return set of partitions with known leaders
Arguments:
topic (str): topic to check for partitions
Returns:
set: {partition (int), ...}
None if topic not found.
"""
if topic not in self._partitions:
return None
return set([partition for partition, metadata
in six.iteritems(self._partitions[topic])
if metadata.leader != -1])
[docs] def leader_for_partition(self, partition):
"""Return node_id of leader, -1 unavailable, None if unknown."""
if partition.topic not in self._partitions:
return None
elif partition.partition not in self._partitions[partition.topic]:
return None
return self._partitions[partition.topic][partition.partition].leader
[docs] def partitions_for_broker(self, broker_id):
"""Return TopicPartitions for which the broker is a leader.
Arguments:
broker_id (int): node id for a broker
Returns:
set: {TopicPartition, ...}
None if the broker either has no partitions or does not exist.
"""
return self._broker_partitions.get(broker_id)
[docs] def coordinator_for_group(self, group):
"""Return node_id of group coordinator.
Arguments:
group (str): name of consumer group
Returns:
int: node_id for group coordinator
None if the group does not exist.
"""
return self._groups.get(group)
[docs] def ttl(self):
"""Milliseconds until metadata should be refreshed"""
now = time.time() * 1000
if self._need_update:
ttl = 0
else:
metadata_age = now - self._last_successful_refresh_ms
ttl = self.config['metadata_max_age_ms'] - metadata_age
retry_age = now - self._last_refresh_ms
next_retry = self.config['retry_backoff_ms'] - retry_age
return max(ttl, next_retry, 0)
[docs] def refresh_backoff(self):
"""Return milliseconds to wait before attempting to retry after failure"""
return self.config['retry_backoff_ms']
[docs] def request_update(self):
"""Flags metadata for update, return Future()
Actual update must be handled separately. This method will only
change the reported ttl()
Returns:
kafka.future.Future (value will be the cluster object after update)
"""
with self._lock:
self._need_update = True
if not self._future or self._future.is_done:
self._future = Future()
return self._future
[docs] def topics(self, exclude_internal_topics=True):
"""Get set of known topics.
Arguments:
exclude_internal_topics (bool): Whether records from internal topics
(such as offsets) should be exposed to the consumer. If set to
True the only way to receive records from an internal topic is
subscribing to it. Default True
Returns:
set: {topic (str), ...}
"""
topics = set(self._partitions.keys())
if exclude_internal_topics:
return topics - self.internal_topics
else:
return topics
[docs] def failed_update(self, exception):
"""Update cluster state given a failed MetadataRequest."""
f = None
with self._lock:
if self._future:
f = self._future
self._future = None
if f:
f.failure(exception)
self._last_refresh_ms = time.time() * 1000
[docs] def update_metadata(self, metadata):
"""Update cluster state given a MetadataResponse.
Arguments:
metadata (MetadataResponse): broker response to a metadata request
Returns: None
"""
# In the common case where we ask for a single topic and get back an
# error, we should fail the future
if len(metadata.topics) == 1 and metadata.topics[0][0] != 0:
error_code, topic = metadata.topics[0][:2]
error = Errors.for_code(error_code)(topic)
return self.failed_update(error)
if not metadata.brokers:
log.warning("No broker metadata found in MetadataResponse -- ignoring.")
return self.failed_update(Errors.MetadataEmptyBrokerList(metadata))
_new_brokers = {}
for broker in metadata.brokers:
if metadata.API_VERSION == 0:
node_id, host, port = broker
rack = None
else:
node_id, host, port, rack = broker
_new_brokers.update({
node_id: BrokerMetadata(node_id, host, port, rack)
})
if metadata.API_VERSION == 0:
_new_controller = None
else:
_new_controller = _new_brokers.get(metadata.controller_id)
_new_partitions = {}
_new_broker_partitions = collections.defaultdict(set)
_new_unauthorized_topics = set()
_new_internal_topics = set()
for topic_data in metadata.topics:
if metadata.API_VERSION == 0:
error_code, topic, partitions = topic_data
is_internal = False
else:
error_code, topic, is_internal, partitions = topic_data
if is_internal:
_new_internal_topics.add(topic)
error_type = Errors.for_code(error_code)
if error_type is Errors.NoError:
_new_partitions[topic] = {}
for p_error, partition, leader, replicas, isr in partitions:
_new_partitions[topic][partition] = PartitionMetadata(
topic=topic, partition=partition, leader=leader,
replicas=replicas, isr=isr, error=p_error)
if leader != -1:
_new_broker_partitions[leader].add(
TopicPartition(topic, partition))
# Specific topic errors can be ignored if this is a full metadata fetch
elif self.need_all_topic_metadata:
continue
elif error_type is Errors.LeaderNotAvailableError:
log.warning("Topic %s is not available during auto-create"
" initialization", topic)
elif error_type is Errors.UnknownTopicOrPartitionError:
log.error("Topic %s not found in cluster metadata", topic)
elif error_type is Errors.TopicAuthorizationFailedError:
log.error("Topic %s is not authorized for this client", topic)
_new_unauthorized_topics.add(topic)
elif error_type is Errors.InvalidTopicError:
log.error("'%s' is not a valid topic name", topic)
else:
log.error("Error fetching metadata for topic %s: %s",
topic, error_type)
with self._lock:
self._brokers = _new_brokers
self.controller = _new_controller
self._partitions = _new_partitions
self._broker_partitions = _new_broker_partitions
self.unauthorized_topics = _new_unauthorized_topics
self.internal_topics = _new_internal_topics
f = None
if self._future:
f = self._future
self._future = None
self._need_update = False
now = time.time() * 1000
self._last_refresh_ms = now
self._last_successful_refresh_ms = now
if f:
f.success(self)
log.debug("Updated cluster metadata to %s", self)
for listener in self._listeners:
listener(self)
if self.need_all_topic_metadata:
# the listener may change the interested topics,
# which could cause another metadata refresh.
# If we have already fetched all topics, however,
# another fetch should be unnecessary.
self._need_update = False
[docs] def add_listener(self, listener):
"""Add a callback function to be called on each metadata update"""
self._listeners.add(listener)
[docs] def remove_listener(self, listener):
"""Remove a previously added listener callback"""
self._listeners.remove(listener)
[docs] def add_group_coordinator(self, group, response):
"""Update with metadata for a group coordinator
Arguments:
group (str): name of group from GroupCoordinatorRequest
response (GroupCoordinatorResponse): broker response
Returns:
string: coordinator node_id if metadata is updated, None on error
"""
log.debug("Updating coordinator for %s: %s", group, response)
error_type = Errors.for_code(response.error_code)
if error_type is not Errors.NoError:
log.error("GroupCoordinatorResponse error: %s", error_type)
self._groups[group] = -1
return
# Use a coordinator-specific node id so that group requests
# get a dedicated connection
node_id = 'coordinator-{}'.format(response.coordinator_id)
coordinator = BrokerMetadata(
node_id,
response.host,
response.port,
None)
log.info("Group coordinator for %s is %s", group, coordinator)
self._coordinator_brokers[node_id] = coordinator
self._groups[group] = node_id
return node_id
[docs] def with_partitions(self, partitions_to_add):
"""Returns a copy of cluster metadata with partitions added"""
new_metadata = ClusterMetadata(**self.config)
new_metadata._brokers = copy.deepcopy(self._brokers)
new_metadata._partitions = copy.deepcopy(self._partitions)
new_metadata._broker_partitions = copy.deepcopy(self._broker_partitions)
new_metadata._groups = copy.deepcopy(self._groups)
new_metadata.internal_topics = copy.deepcopy(self.internal_topics)
new_metadata.unauthorized_topics = copy.deepcopy(self.unauthorized_topics)
for partition in partitions_to_add:
new_metadata._partitions[partition.topic][partition.partition] = partition
if partition.leader is not None and partition.leader != -1:
new_metadata._broker_partitions[partition.leader].add(
TopicPartition(partition.topic, partition.partition))
return new_metadata
def __str__(self):
return 'ClusterMetadata(brokers: %d, topics: %d, groups: %d)' % \
(len(self._brokers), len(self._partitions), len(self._groups))