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# Copyright 2009 Google Inc. All Rights Reserved.
#
# 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
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Simple DNS server comparison benchmarking tool.
Designed to assist system administrators in selection and prioritization.
"""
__author__ = 'tstromberg@google.com (Thomas Stromberg)'
import Queue
import random
import threading
import time
class BenchmarkThreads(threading.Thread):
"""Benchmark multiple nameservers in parallel."""
def __init__(self, input_queue, results_queue):
threading.Thread.__init__(self)
self.input = input_queue
self.results = results_queue
def run(self):
"""Iterate over the queue, processing each item."""
while not self.input.empty():
try:
(ns, request_type, hostname) = self.input.get_nowait()
# We've moved this here so that it's after all of the random selection goes through.
if '__RANDOM__' in hostname:
hostname = hostname.replace('__RANDOM__', str(random.random() * random.randint(0, 99999)))
(response, duration, error_msg) = ns.TimedRequest(request_type, hostname)
self.results.put((ns, request_type, hostname, response, duration, error_msg))
except Queue.Empty:
return
class Benchmark(object):
"""The main benchmarking class."""
def __init__(self, nameservers, run_count=2, query_count=30, thread_count=1,
status_callback=None):
"""Constructor.
Args:
nameservers: a list of NameServerData objects
run_count: How many test-runs to perform on each nameserver (int)
query_count: How many DNS lookups to test in each test-run (int)
thread_count: How many benchmark threads to use (int)
status_callback: Where to send msg() updates to.
"""
self.query_count = query_count
self.run_count = run_count
self.thread_count = thread_count
self.nameservers = nameservers
self.results = {}
self.status_callback = status_callback
def msg(self, msg, **kwargs):
if self.status_callback:
self.status_callback(msg, **kwargs)
def _CheckForIndexHostsInResults(self, test_records):
"""Check if we have already tested index hosts.
Args:
test_records: List of tuples of test records (type, record)
Returns:
A list of results that have already been tested
A list of records that still need to be tested.
"""
needs_test = []
index_results = {}
for test in test_records:
matched = False
for ns in self.results:
for result in self.results[ns][0]:
hostname, request_type = result[0:2]
if (request_type, hostname) == test:
matched = True
index_results.setdefault(ns, []).append(result)
# So that we don't include the second results if duplicates exist.
break
if not matched:
needs_test.append(test)
return (index_results, needs_test)
def RunIndex(self, test_records):
"""Run index tests using the same mechanism as a standard benchmark."""
if not test_records:
print 'No records to test.'
return None
index_results, pending_tests = self._CheckForIndexHostsInResults(test_records)
run_results = self._SingleTestRun(pending_tests)
for ns in run_results:
index_results.setdefault(ns, []).extend(run_results[ns])
return index_results
def Run(self, test_records=None):
"""Run all test runs for all nameservers."""
# We don't want to keep stats on how many queries timed out from previous runs.
for ns in self.nameservers.enabled:
ns.ResetErrorCounts()
for _ in range(self.run_count):
run_results = self._SingleTestRun(test_records)
for ns in run_results:
self.results.setdefault(ns, []).append(run_results[ns])
return self.results
def _SingleTestRun(self, test_records):
"""Manage and execute a single test-run on all nameservers.
We used to run all tests for a nameserver, but the results proved to be
unfair if the bandwidth was suddenly constrained. We now run a test on
each server before moving on to the next.
Args:
test_records: a list of tuples in the form of (request_type, hostname)
Returns:
results: A dictionary of tuples, keyed by nameserver.
"""
input_queue = Queue.Queue()
shuffled_records = {}
results = {}
# Pre-compute the shuffled test records per-nameserver to avoid thread
# contention.
for ns in self.nameservers.enabled:
random.shuffle(test_records)
shuffled_records[ns.ip] = list(test_records)
# Feed the pre-computed records into the input queue.
for i in range(len(test_records)):
for ns in self.nameservers.enabled:
(request_type, hostname) = shuffled_records[ns.ip][i]
input_queue.put((ns, request_type, hostname))
results_queue = self._LaunchBenchmarkThreads(input_queue)
errors = []
while results_queue.qsize():
(ns, request_type, hostname, response, duration, error_msg) = results_queue.get()
if error_msg:
duration = ns.timeout * 1000
errors.append((ns, error_msg))
results.setdefault(ns, []).append((hostname, request_type, duration, response, error_msg))
for (ns, error_msg) in errors:
self.msg('Error querying %s: %s' % (ns, error_msg))
return results
def _LaunchBenchmarkThreads(self, input_queue):
"""Launch and manage the benchmark threads."""
results_queue = Queue.Queue()
expected_total = input_queue.qsize()
threads = []
for unused_thread_num in range(0, self.thread_count):
thread = BenchmarkThreads(input_queue, results_queue)
thread.start()
threads.append(thread)
query_count = expected_total / len(self.nameservers.enabled)
status_message = ('Sending %s queries to %s servers' %
(query_count, len(self.nameservers.enabled)))
while results_queue.qsize() != expected_total:
self.msg(status_message, count=results_queue.qsize(), total=expected_total)
time.sleep(0.5)
self.msg(status_message, count=results_queue.qsize(), total=expected_total)
for thread in threads:
thread.join()
return results_queue
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