Source code for cassandra.metrics

# Copyright DataStax, Inc.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

from itertools import chain
import logging

    from greplin import scales
except ImportError:
    raise ImportError(
        "The scales library is required for metrics support: "

log = logging.getLogger(__name__)

[docs]class Metrics(object): """ A collection of timers and counters for various performance metrics. Timer metrics are represented as floating point seconds. """ request_timer = None """ A :class:`greplin.scales.PmfStat` timer for requests. This is a dict-like object with the following keys: * count - number of requests that have been timed * min - min latency * max - max latency * mean - mean latency * stddev - standard deviation for latencies * median - median latency * 75percentile - 75th percentile latencies * 95percentile - 95th percentile latencies * 98percentile - 98th percentile latencies * 99percentile - 99th percentile latencies * 999percentile - 99.9th percentile latencies """ connection_errors = None """ A :class:`greplin.scales.IntStat` count of the number of times that a request to a Cassandra node has failed due to a connection problem. """ write_timeouts = None """ A :class:`greplin.scales.IntStat` count of write requests that resulted in a timeout. """ read_timeouts = None """ A :class:`greplin.scales.IntStat` count of read requests that resulted in a timeout. """ unavailables = None """ A :class:`greplin.scales.IntStat` count of write or read requests that failed due to an insufficient number of replicas being alive to meet the requested :class:`.ConsistencyLevel`. """ other_errors = None """ A :class:`greplin.scales.IntStat` count of all other request failures, including failures caused by invalid requests, bootstrapping nodes, overloaded nodes, etc. """ retries = None """ A :class:`greplin.scales.IntStat` count of the number of times a request was retried based on the :class:`.RetryPolicy` decision. """ ignores = None """ A :class:`greplin.scales.IntStat` count of the number of times a failed request was ignored based on the :class:`.RetryPolicy` decision. """ known_hosts = None """ A :class:`greplin.scales.IntStat` count of the number of nodes in the cluster that the driver is aware of, regardless of whether any connections are opened to those nodes. """ connected_to = None """ A :class:`greplin.scales.IntStat` count of the number of nodes that the driver currently has at least one connection open to. """ open_connections = None """ A :class:`greplin.scales.IntStat` count of the number connections the driver currently has open. """ _stats_counter = 0 def __init__(self, cluster_proxy): log.debug("Starting metric capture") self.stats_name = 'cassandra-{0}'.format(str(self._stats_counter)) Metrics._stats_counter += 1 self.stats = scales.collection(self.stats_name, scales.PmfStat('request_timer'), scales.IntStat('connection_errors'), scales.IntStat('write_timeouts'), scales.IntStat('read_timeouts'), scales.IntStat('unavailables'), scales.IntStat('other_errors'), scales.IntStat('retries'), scales.IntStat('ignores'), # gauges scales.Stat('known_hosts', lambda: len(cluster_proxy.metadata.all_hosts())), scales.Stat('connected_to', lambda: len(set(chain.from_iterable(s._pools.keys() for s in cluster_proxy.sessions)))), scales.Stat('open_connections', lambda: sum(sum(p.open_count for p in s._pools.values()) for s in cluster_proxy.sessions))) # TODO, to be removed in 4.0 # /cassandra contains the metrics of the first cluster registered if 'cassandra' not in scales._Stats.stats: scales._Stats.stats['cassandra'] = scales._Stats.stats[self.stats_name] self.request_timer = self.stats.request_timer self.connection_errors = self.stats.connection_errors self.write_timeouts = self.stats.write_timeouts self.read_timeouts = self.stats.read_timeouts self.unavailables = self.stats.unavailables self.other_errors = self.stats.other_errors self.retries = self.stats.retries self.ignores = self.stats.ignores self.known_hosts = self.stats.known_hosts self.connected_to = self.stats.connected_to self.open_connections = self.stats.open_connections def on_connection_error(self): self.stats.connection_errors += 1 def on_write_timeout(self): self.stats.write_timeouts += 1 def on_read_timeout(self): self.stats.read_timeouts += 1 def on_unavailable(self): self.stats.unavailables += 1 def on_other_error(self): self.stats.other_errors += 1 def on_ignore(self): self.stats.ignores += 1 def on_retry(self): self.stats.retries += 1
[docs] def get_stats(self): """ Returns the metrics for the registered cluster instance. """ return scales.getStats()[self.stats_name]
[docs] def set_stats_name(self, stats_name): """ Set the metrics stats name. The stats_name is a string used to access the metris through scales: scales.getStats()[<stats_name>] Default is 'cassandra-<num>'. """ if self.stats_name == stats_name: return if stats_name in scales._Stats.stats: raise ValueError('"{0}" already exists in stats.'.format(stats_name)) stats = scales._Stats.stats[self.stats_name] del scales._Stats.stats[self.stats_name] self.stats_name = stats_name scales._Stats.stats[self.stats_name] = stats