445 lines
18 KiB
Python
445 lines
18 KiB
Python
from __future__ import absolute_import
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try:
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from itertools import zip_longest as izip_longest, repeat # pylint: disable=E0611
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except ImportError:
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from itertools import izip_longest as izip_longest, repeat # pylint: disable=E0611
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import logging
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import sys
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import time
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import warnings
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from kafka.vendor import six
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from kafka.vendor.six.moves import queue # pylint: disable=import-error
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from .base import (
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Consumer,
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FETCH_DEFAULT_BLOCK_TIMEOUT,
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AUTO_COMMIT_MSG_COUNT,
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AUTO_COMMIT_INTERVAL,
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FETCH_MIN_BYTES,
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FETCH_BUFFER_SIZE_BYTES,
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MAX_FETCH_BUFFER_SIZE_BYTES,
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FETCH_MAX_WAIT_TIME,
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ITER_TIMEOUT_SECONDS,
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NO_MESSAGES_WAIT_TIME_SECONDS
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)
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from ..common import (
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FetchRequestPayload, KafkaError, OffsetRequestPayload,
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ConsumerFetchSizeTooSmall,
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UnknownTopicOrPartitionError, NotLeaderForPartitionError,
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OffsetOutOfRangeError, FailedPayloadsError, check_error
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)
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from kafka.protocol.message import PartialMessage
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log = logging.getLogger(__name__)
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class FetchContext(object):
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"""
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Class for managing the state of a consumer during fetch
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"""
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def __init__(self, consumer, block, timeout):
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warnings.warn('deprecated - this class will be removed in a future'
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' release', DeprecationWarning)
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self.consumer = consumer
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self.block = block
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if block:
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if not timeout:
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timeout = FETCH_DEFAULT_BLOCK_TIMEOUT
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self.timeout = timeout * 1000
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def __enter__(self):
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"""Set fetch values based on blocking status"""
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self.orig_fetch_max_wait_time = self.consumer.fetch_max_wait_time
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self.orig_fetch_min_bytes = self.consumer.fetch_min_bytes
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if self.block:
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self.consumer.fetch_max_wait_time = self.timeout
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self.consumer.fetch_min_bytes = 1
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else:
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self.consumer.fetch_min_bytes = 0
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def __exit__(self, type, value, traceback):
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"""Reset values"""
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self.consumer.fetch_max_wait_time = self.orig_fetch_max_wait_time
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self.consumer.fetch_min_bytes = self.orig_fetch_min_bytes
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class SimpleConsumer(Consumer):
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"""
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A simple consumer implementation that consumes all/specified partitions
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for a topic
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Arguments:
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client: a connected SimpleClient
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group: a name for this consumer, used for offset storage and must be unique
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If you are connecting to a server that does not support offset
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commit/fetch (any prior to 0.8.1.1), then you *must* set this to None
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topic: the topic to consume
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Keyword Arguments:
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partitions: An optional list of partitions to consume the data from
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auto_commit: default True. Whether or not to auto commit the offsets
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auto_commit_every_n: default 100. How many messages to consume
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before a commit
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auto_commit_every_t: default 5000. How much time (in milliseconds) to
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wait before commit
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fetch_size_bytes: number of bytes to request in a FetchRequest
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buffer_size: default 4K. Initial number of bytes to tell kafka we
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have available. This will double as needed.
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max_buffer_size: default 16K. Max number of bytes to tell kafka we have
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available. None means no limit.
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iter_timeout: default None. How much time (in seconds) to wait for a
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message in the iterator before exiting. None means no
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timeout, so it will wait forever.
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auto_offset_reset: default largest. Reset partition offsets upon
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OffsetOutOfRangeError. Valid values are largest and smallest.
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Otherwise, do not reset the offsets and raise OffsetOutOfRangeError.
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Auto commit details:
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If both auto_commit_every_n and auto_commit_every_t are set, they will
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reset one another when one is triggered. These triggers simply call the
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commit method on this class. A manual call to commit will also reset
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these triggers
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"""
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def __init__(self, client, group, topic, auto_commit=True, partitions=None,
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auto_commit_every_n=AUTO_COMMIT_MSG_COUNT,
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auto_commit_every_t=AUTO_COMMIT_INTERVAL,
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fetch_size_bytes=FETCH_MIN_BYTES,
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buffer_size=FETCH_BUFFER_SIZE_BYTES,
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max_buffer_size=MAX_FETCH_BUFFER_SIZE_BYTES,
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iter_timeout=None,
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auto_offset_reset='largest'):
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warnings.warn('deprecated - this class will be removed in a future'
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' release. Use KafkaConsumer instead.',
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DeprecationWarning)
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super(SimpleConsumer, self).__init__(
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client, group, topic,
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partitions=partitions,
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auto_commit=auto_commit,
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auto_commit_every_n=auto_commit_every_n,
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auto_commit_every_t=auto_commit_every_t)
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if max_buffer_size is not None and buffer_size > max_buffer_size:
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raise ValueError('buffer_size (%d) is greater than '
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'max_buffer_size (%d)' %
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(buffer_size, max_buffer_size))
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self.buffer_size = buffer_size
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self.max_buffer_size = max_buffer_size
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self.fetch_max_wait_time = FETCH_MAX_WAIT_TIME
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self.fetch_min_bytes = fetch_size_bytes
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self.fetch_offsets = self.offsets.copy()
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self.iter_timeout = iter_timeout
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self.auto_offset_reset = auto_offset_reset
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self.queue = queue.Queue()
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def __repr__(self):
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return '<SimpleConsumer group=%s, topic=%s, partitions=%s>' % \
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(self.group, self.topic, str(self.offsets.keys()))
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def reset_partition_offset(self, partition):
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"""Update offsets using auto_offset_reset policy (smallest|largest)
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Arguments:
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partition (int): the partition for which offsets should be updated
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Returns: Updated offset on success, None on failure
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"""
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LATEST = -1
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EARLIEST = -2
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if self.auto_offset_reset == 'largest':
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reqs = [OffsetRequestPayload(self.topic, partition, LATEST, 1)]
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elif self.auto_offset_reset == 'smallest':
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reqs = [OffsetRequestPayload(self.topic, partition, EARLIEST, 1)]
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else:
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# Let's raise an reasonable exception type if user calls
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# outside of an exception context
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if sys.exc_info() == (None, None, None):
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raise OffsetOutOfRangeError('Cannot reset partition offsets without a '
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'valid auto_offset_reset setting '
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'(largest|smallest)')
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# Otherwise we should re-raise the upstream exception
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# b/c it typically includes additional data about
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# the request that triggered it, and we do not want to drop that
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raise # pylint: disable=E0704
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# send_offset_request
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log.info('Resetting topic-partition offset to %s for %s:%d',
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self.auto_offset_reset, self.topic, partition)
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try:
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(resp, ) = self.client.send_offset_request(reqs)
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except KafkaError as e:
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log.error('%s sending offset request for %s:%d',
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e.__class__.__name__, self.topic, partition)
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else:
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self.offsets[partition] = resp.offsets[0]
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self.fetch_offsets[partition] = resp.offsets[0]
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return resp.offsets[0]
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def seek(self, offset, whence=None, partition=None):
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"""
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Alter the current offset in the consumer, similar to fseek
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Arguments:
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offset: how much to modify the offset
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whence: where to modify it from, default is None
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* None is an absolute offset
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* 0 is relative to the earliest available offset (head)
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* 1 is relative to the current offset
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* 2 is relative to the latest known offset (tail)
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partition: modify which partition, default is None.
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If partition is None, would modify all partitions.
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"""
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if whence is None: # set an absolute offset
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if partition is None:
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for tmp_partition in self.offsets:
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self.offsets[tmp_partition] = offset
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else:
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self.offsets[partition] = offset
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elif whence == 1: # relative to current position
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if partition is None:
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for tmp_partition, _offset in self.offsets.items():
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self.offsets[tmp_partition] = _offset + offset
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else:
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self.offsets[partition] += offset
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elif whence in (0, 2): # relative to beginning or end
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reqs = []
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deltas = {}
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if partition is None:
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# divide the request offset by number of partitions,
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# distribute the remained evenly
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(delta, rem) = divmod(offset, len(self.offsets))
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for tmp_partition, r in izip_longest(self.offsets.keys(),
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repeat(1, rem),
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fillvalue=0):
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deltas[tmp_partition] = delta + r
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for tmp_partition in self.offsets.keys():
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if whence == 0:
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reqs.append(OffsetRequestPayload(self.topic, tmp_partition, -2, 1))
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elif whence == 2:
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reqs.append(OffsetRequestPayload(self.topic, tmp_partition, -1, 1))
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else:
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pass
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else:
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deltas[partition] = offset
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if whence == 0:
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reqs.append(OffsetRequestPayload(self.topic, partition, -2, 1))
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elif whence == 2:
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reqs.append(OffsetRequestPayload(self.topic, partition, -1, 1))
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else:
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pass
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resps = self.client.send_offset_request(reqs)
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for resp in resps:
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self.offsets[resp.partition] = \
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resp.offsets[0] + deltas[resp.partition]
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else:
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raise ValueError('Unexpected value for `whence`, %d' % whence)
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# Reset queue and fetch offsets since they are invalid
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self.fetch_offsets = self.offsets.copy()
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self.count_since_commit += 1
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if self.auto_commit:
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self.commit()
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self.queue = queue.Queue()
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def get_messages(self, count=1, block=True, timeout=0.1):
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"""
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Fetch the specified number of messages
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Keyword Arguments:
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count: Indicates the maximum number of messages to be fetched
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block: If True, the API will block till all messages are fetched.
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If block is a positive integer the API will block until that
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many messages are fetched.
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timeout: When blocking is requested the function will block for
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the specified time (in seconds) until count messages is
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fetched. If None, it will block forever.
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"""
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messages = []
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if timeout is not None:
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timeout += time.time()
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new_offsets = {}
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log.debug('getting %d messages', count)
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while len(messages) < count:
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block_time = timeout - time.time()
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log.debug('calling _get_message block=%s timeout=%s', block, block_time)
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block_next_call = block is True or block > len(messages)
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result = self._get_message(block_next_call, block_time,
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get_partition_info=True,
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update_offset=False)
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log.debug('got %s from _get_messages', result)
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if not result:
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if block_next_call and (timeout is None or time.time() <= timeout):
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continue
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break
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partition, message = result
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_msg = (partition, message) if self.partition_info else message
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messages.append(_msg)
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new_offsets[partition] = message.offset + 1
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# Update and commit offsets if necessary
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self.offsets.update(new_offsets)
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self.count_since_commit += len(messages)
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self._auto_commit()
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log.debug('got %d messages: %s', len(messages), messages)
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return messages
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def get_message(self, block=True, timeout=0.1, get_partition_info=None):
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return self._get_message(block, timeout, get_partition_info)
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def _get_message(self, block=True, timeout=0.1, get_partition_info=None,
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update_offset=True):
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"""
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If no messages can be fetched, returns None.
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If get_partition_info is None, it defaults to self.partition_info
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If get_partition_info is True, returns (partition, message)
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If get_partition_info is False, returns message
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"""
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start_at = time.time()
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while self.queue.empty():
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# We're out of messages, go grab some more.
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log.debug('internal queue empty, fetching more messages')
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with FetchContext(self, block, timeout):
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self._fetch()
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if not block or time.time() > (start_at + timeout):
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break
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try:
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partition, message = self.queue.get_nowait()
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if update_offset:
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# Update partition offset
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self.offsets[partition] = message.offset + 1
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# Count, check and commit messages if necessary
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self.count_since_commit += 1
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self._auto_commit()
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if get_partition_info is None:
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get_partition_info = self.partition_info
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if get_partition_info:
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return partition, message
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else:
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return message
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except queue.Empty:
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log.debug('internal queue empty after fetch - returning None')
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return None
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def __iter__(self):
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if self.iter_timeout is None:
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timeout = ITER_TIMEOUT_SECONDS
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else:
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timeout = self.iter_timeout
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while True:
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message = self.get_message(True, timeout)
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if message:
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yield message
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elif self.iter_timeout is None:
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# We did not receive any message yet but we don't have a
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# timeout, so give up the CPU for a while before trying again
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time.sleep(NO_MESSAGES_WAIT_TIME_SECONDS)
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else:
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# Timed out waiting for a message
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break
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def _fetch(self):
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# Create fetch request payloads for all the partitions
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partitions = dict((p, self.buffer_size)
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for p in self.fetch_offsets.keys())
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while partitions:
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requests = []
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for partition, buffer_size in six.iteritems(partitions):
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requests.append(FetchRequestPayload(self.topic, partition,
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self.fetch_offsets[partition],
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buffer_size))
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# Send request
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responses = self.client.send_fetch_request(
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requests,
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max_wait_time=int(self.fetch_max_wait_time),
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min_bytes=self.fetch_min_bytes,
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fail_on_error=False
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)
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retry_partitions = {}
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for resp in responses:
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try:
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check_error(resp)
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except UnknownTopicOrPartitionError:
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log.error('UnknownTopicOrPartitionError for %s:%d',
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resp.topic, resp.partition)
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self.client.reset_topic_metadata(resp.topic)
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raise
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except NotLeaderForPartitionError:
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log.error('NotLeaderForPartitionError for %s:%d',
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resp.topic, resp.partition)
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self.client.reset_topic_metadata(resp.topic)
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continue
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except OffsetOutOfRangeError:
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log.warning('OffsetOutOfRangeError for %s:%d. '
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'Resetting partition offset...',
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resp.topic, resp.partition)
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self.reset_partition_offset(resp.partition)
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# Retry this partition
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retry_partitions[resp.partition] = partitions[resp.partition]
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continue
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except FailedPayloadsError as e:
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log.warning('FailedPayloadsError for %s:%d',
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e.payload.topic, e.payload.partition)
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# Retry this partition
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retry_partitions[e.payload.partition] = partitions[e.payload.partition]
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continue
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partition = resp.partition
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buffer_size = partitions[partition]
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# Check for partial message
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if resp.messages and isinstance(resp.messages[-1].message, PartialMessage):
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# If buffer is at max and all we got was a partial message
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# raise ConsumerFetchSizeTooSmall
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if (self.max_buffer_size is not None and
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buffer_size == self.max_buffer_size and
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len(resp.messages) == 1):
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log.error('Max fetch size %d too small', self.max_buffer_size)
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raise ConsumerFetchSizeTooSmall()
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if self.max_buffer_size is None:
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buffer_size *= 2
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else:
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buffer_size = min(buffer_size * 2, self.max_buffer_size)
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log.warning('Fetch size too small, increase to %d (2x) '
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'and retry', buffer_size)
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retry_partitions[partition] = buffer_size
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resp.messages.pop()
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for message in resp.messages:
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if message.offset < self.fetch_offsets[partition]:
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log.debug('Skipping message %s because its offset is less than the consumer offset',
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message)
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continue
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# Put the message in our queue
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self.queue.put((partition, message))
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self.fetch_offsets[partition] = message.offset + 1
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partitions = retry_partitions
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