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webvirtcloud/instances/test_stats_sample.py
catborise 24231813d7 perf(instances): the VM stats no longer wait a second per poll
Each stats answer carries a signed sample of the counters, bound to the VM,
its compute and UUID. The next poll sends it back and the rates are the
averages since then; a sample from another run of the VM (domain ID),
another host CPU count or device list, or older than 30 s falls back to
one second as before. Windows are measured on the monotonic clock.

Now that a poll is cheap, the Stats tab polls every 5 s like the host
graph, the first time as soon as it opens (pollWhileVisible takes the
delay of the first request).

A counter the host reports as unsupported (-1) or that went back gives no
value instead of 0 or a jump; a NIC without a target keeps its chart, a
pool volume disk is measured, and a disk or NIC attached after the page
loaded no longer stops the other charts. Disk rates are MB/s (they were
MiB/s labelled Mb/s), network Mbit/s; the CPU tooltip names the window.
2026-10-09 11:59:41 +03:00

194 lines
9.6 KiB
Python

"""The VM stats: each answer carries a signed usage sample bound to the VM on
its compute; the next poll sends it back so that the rates are averages since
then, without waiting."""
import json
import re
import shutil
import subprocess
import unittest
from unittest.mock import patch
import libvirt
from computes.models import Compute
from django.contrib.auth import get_user_model
from django.core import signing
from django.test import TestCase
from django.urls import reverse
from instances.models import Instance
from vrtManager.instance import USAGE_MAX_WINDOW
SAMPLE = {"key": [7, 4, ["vda"], [["52:54:00:00:00:01", "vnet0"]]], "counters": [1, [[2, 3]], [[4, 5]], 100.0]}
class StatsViewTestCase(TestCase):
def setUp(self):
self.compute = Compute.objects.create(name="stats", hostname="192.0.2.1", login="u", password="p", type=1)
self.other_compute = Compute.objects.create(name="stats2", hostname="192.0.2.2", login="u", password="p", type=1)
uuid = "5d1b8a3e-0000-4000-8000-000000000001"
self.vm = Instance.objects.create(compute=self.compute, name="stats-vm", uuid=uuid)
self.other = Instance.objects.create(compute=self.compute, name="stats-vm2", uuid=uuid.replace("1", "2"))
self.client.force_login(get_user_model().objects.create_superuser("sv-admin", "sv@example.com", "pw"))
patcher = patch("instances.models.wvmInstance")
self.addCleanup(patcher.stop)
self.proxy = patcher.start().return_value
self.proxy.mem_usage.return_value = {"used": 1, "total": 2}
self.proxy.usage.return_value = {
"cpu": 12.345,
"disks": [{"dev": "vda", "rd": 2_000_000, "wr": None}],
"nics": [{"dev": 0, "rx": 8_000_000, "tx": 0}],
"window": 9.96,
"sample": SAMPLE,
}
def stats(self, vm=None, **params):
response = self.client.get(reverse("instances:stats", args=[(vm or self.vm).id]), params)
self.assertEqual(response.status_code, 200)
return json.loads(response.content)
def previous(self):
return self.proxy.usage.call_args.args[0]
def test_rates_in_mb_and_mbit_per_second_and_the_sample_round_trip(self):
data = self.stats()
self.assertIsNone(self.previous())
self.assertEqual((data["cpudata"], data["window"]), (12.3, 10.0))
self.assertEqual(data["blkdata"], [{"dev": "vda", "data": [2.0, None]}])
self.assertEqual(data["netdata"], [{"dev": 0, "data": [8.0, 0.0]}])
self.stats(sample=data["sample"])
self.assertEqual(self.previous(), SAMPLE)
def test_an_altered_old_or_foreign_sample_is_not_used(self):
token = self.stats()["sample"]
foreign = self.stats(self.other)["sample"]
altered = token[:-2] + ("xx" if not token.endswith("xx") else "yy")
for name, sample in (("altered", altered), ("garbage", "x"), ("other VM", foreign)):
with self.subTest(name):
self.stats(sample=sample)
self.assertIsNone(self.previous())
with patch("django.core.signing.time.time", return_value=signing.time.time() + USAGE_MAX_WINDOW + 1):
self.stats(sample=token)
self.assertIsNone(self.previous())
def test_a_sample_from_before_a_migration_is_not_used(self):
token = self.stats()["sample"]
Instance.objects.filter(pk=self.vm.pk).update(compute=self.other_compute)
self.stats(sample=token)
self.assertIsNone(self.previous())
def test_a_vm_that_is_not_running_gives_no_sample(self):
self.proxy.usage.return_value = {"cpu": 0, "disks": [], "nics": []}
data = self.stats()
self.assertEqual(data["cpudata"], 0)
self.assertNotIn("sample", data)
self.assertNotIn("window", data)
# a VM with a disk and a NIC, on libvirt's test driver
DOMAIN = """<domain type='test'><name>stats-script-vm</name><uuid>3c0e2b7a-91d4-4f5e-8a6b-0d2f4e6a8c10</uuid>
<memory unit='MiB'>128</memory><vcpu>1</vcpu><os><type arch='i686'>hvm</type></os>
<devices><disk type='file' device='disk'><source file='/default-pool/stats-script.img'/><target dev='vda' bus='virtio'/></disk>
<interface type='network'><mac address='52:54:00:00:00:31'/><source network='default'/><model type='virtio'/></interface></devices>
</domain>"""
class TestDriverVM:
def setUp(self):
self.conn = libvirt.open("test:///default")
self.addCleanup(self.conn.close)
# the test host lives on while a libvirt object still refers to it
pool = self.conn.storagePoolLookupByName("default-pool")
if "stats-script.img" not in pool.listVolumes():
pool.createXML("<volume><name>stats-script.img</name><capacity>1048576</capacity></volume>", 0)
self.domain = self.conn.defineXML(DOMAIN)
compute = Compute.objects.create(name="ss", hostname="localhost", login="", password="", type=4)
self.vm = Instance.objects.create(compute=compute, name=self.domain.name(), uuid=self.domain.UUIDString())
self.client.force_login(get_user_model().objects.create_superuser("ss-admin", "ss@example.com", "pw"))
for target, value in (
("vrtManager.connection.connection_manager.get_connection", self.conn),
("vrtManager.connection.wvmConnect.get_machine_types", ["pc"]),
("vrtManager.connection.wvmConnect.get_nwfilters", []),
):
patcher = patch(target, return_value=value)
patcher.start()
self.addCleanup(patcher.stop)
class SampleRoundTripTestCase(TestDriverVM, TestCase):
def test_a_real_sample_is_used_by_the_next_poll(self):
self.domain.create()
self.addCleanup(self.domain.destroy)
url = reverse("instances:stats", args=[self.vm.id])
with patch("vrtManager.instance.time.sleep") as sleep:
first = json.loads(self.client.get(url).content)
sleep.assert_called_once_with(1)
sleep.reset_mock()
second = json.loads(self.client.get(url, {"sample": first["sample"]}).content)
sleep.assert_not_called()
self.assertEqual([disk["dev"] for disk in second["blkdata"]], ["vda"])
self.assertIn("sample", second)
@unittest.skipUnless(shutil.which("node"), "node is not installed")
class StatsScriptTestCase(TestDriverVM, TestCase):
"""The VM page's script sends each answer's sample with the next poll and
drops it after a failed one."""
def page(self):
response = self.client.get(reverse("instances:instance", args=[self.vm.id]))
self.assertEqual(response.status_code, 200)
return response.content.decode()
def test_the_next_poll_sends_the_previous_sample(self):
script = next(s for s in re.findall(r"<script>(.*?)</script>", self.page(), re.S) if "statsSample" in s)
js = """
const vm = require("vm");
const charts = [], requests = [], handlers = {};
let poll, fail = false;
const canvas = {get: () => ({getContext: () => ({})})};
const $ = () => canvas;
$.getJSON = (url, params) => {
requests.push(params);
return {fail: (callback) => { if (fail) callback(); return {}; }};
};
const page = {
$,
document: {querySelector: () => ({addEventListener: (name, handler) => { handlers[name] = handler; }})},
// Chart.js adds the lists a config leaves out
Chart: function (ctx, config) {
this.data = Object.assign({labels: []}, config.data);
this.data.datasets.forEach((set) => { set.data = set.data || []; });
this.options = config.options;
this.update = () => {};
charts.push(this);
},
pollWhileVisible: (interval, request, onData, first) => { poll = {interval, first, request, onData}; return {}; },
};
vm.runInNewContext(SCRIPT, vm.createContext(page));
handlers["shown.bs.tab"]();
const answer = (cpu, sample) => ({cpudata: cpu, window: 9.9, sample: sample, timeline: "t",
memdata: {used: 0, total: 1024},
// vdb was attached after the page loaded
blkdata: [{dev: "vdb", data: [9, 9]}, {dev: "vda", data: [1.5, null]}],
netdata: [{dev: 0, data: [2, 3]}]});
poll.request();
poll.onData(answer(3, "token-1"));
poll.request();
fail = true;
poll.request();
fail = false;
poll.request();
const label = charts[0].options.tooltips.callbacks.label({datasetIndex: 0, index: 0, yLabel: 3}, charts[0].data);
console.log(JSON.stringify({requests, label, every: [poll.interval, poll.first], cpu: charts[0].data.datasets[0].data,
disk: charts[2].data.datasets[1].data, net: charts[3].data.datasets[0].data}));
""".replace("SCRIPT", json.dumps(script))
out = subprocess.run(["node", "-e", js], capture_output=True, text=True, timeout=30)
self.assertEqual(out.returncode, 0, out.stderr)
result = json.loads(out.stdout)
# the first poll at once, then every 5 s
self.assertEqual(result["every"], [5000, 0])
# the sample goes with the next poll; a failed poll drops it
self.assertEqual(result["requests"], [{}, {"sample": "token-1"}, {"sample": "token-1"}, {}])
# a disk without a chart is skipped, the other charts still update
self.assertEqual((result["cpu"], result["disk"], result["net"]), ([3], [None], [2]))
self.assertTrue(result["label"].endswith(": 3 % (average over 9.9 s)"), result["label"])